Galloper Wind Farm Project - Galloper Wind Farm proposal

Galloper Wind Farm Project 

Environmental Statement – Chapter 13: Natural Fish and 

Shellfish Resources 

October 2011 

Document Reference – 5.2.13 

Galloper Wind Farm Limited

Document title Galloper Wind Farm Project 

Environmental Statement – Chapter 13: Natural 

Fish and Shellfish Resources 

Document short title Galloper Wind Farm ES 

Document Reference 5.2.13 

Regulation Reference APFP Regulations, 5(2)(a) 

Version 7 

Status Final Report 

Date October 2011 

Project name Galloper Wind Farm Project 

Client Galloper Wind Farm Limited 

Royal Haskoning 

Reference 

9V3083/R01/303730/Exet 

Drafted by Randolph Velterop 

Checked by Peter Gaches 

Date/initials check PG 28.09.2011 

Approved by Martin Budd 

Date/initials approval MB 19.10.2011 

GWFL Approved by Kate Harvey 

Date/initials approval KH 01.11.2011 

Galloper Wind Farm ES 9V3083/R01/303730/Exet 

Final Report - i - October 2011

CONTENTS 

Page 

13 FISH AND SHELLFISH RESOURCES 1 

13.1 Introduction 1 

13.2 Guidance and Consultation 1 

13.3 Methodology 7 

13.4 Existing Environment 13 

13.5 Assessment of Impacts – Worst Case Definition 68 

13.6 Potential Impacts during the Construction Phase 81 

13.7 Potential Impacts during the Operational Phase 111 

13.8 Potential Impacts during Decommissioning 118 

13.9 Inter-relationships 119 

13.10 Cumulative Impacts 121 

13.11 Transboundary Effects 133 

13.12 Monitoring 133 

13.13 Summary 134 

13.14 References 137 

Technical Appendix 13.A Fish Resource Surveys (2008-2009) 

Technical Appendix 13.B Underwater Noise Impact Assessment 

Technical Appendix 13.C Supplementary Herring Spawning Information 


Final Report - ii - October 2011

13 FISH AND SHELLFISH RESOURCES 

13.1 Introduction 

13.1.1 This Chapter of the Environmental Statement (ES) describes the existing 

environment with regard to the natural fish and shellfish resource within the 

proposed Galloper Wind Farm (GWF) project, as well as the wider area of 

the Outer Thames Estuary and southern North Sea. 

13.1.2 This Chapter serves to provide a description of the distribution and seasonal 

abundance of fish and shellfish species known to occur, or which have been 

recorded within both the study area and across the wider region. This 

description draws upon data collected through site specific and / or regional 

surveys, both in the published and grey literature and as a result of original 

data collection. Subsequent to this, the assessment of potential impacts of 

the construction, operation and decommissioning phases of the proposed 

GWF project on the existing environment are presented and detail on the 

proposed mitigation that will be considered by Galloper Wind Farm Limited 

(GWFL) are also provided. Finally, approaches to monitoring are presented. 

13.1.3 For the purposes of the Infrastructure Planning (Applications: Prescribed 

Forms and Procedure) Regulations 2009, Figures 13.4 to 13.10 and Figures 

13.13 to 13.20 taken together with this Chapter, fulfil the requirements of 

Regulation 5(2)(l) in relation to the effects of the proposed development on 

fish and shellfish resources. 

13.2 Guidance and Consultation 

Legislation, policy and guidance 

13.2.1 The assessment of potential impacts upon fish and shellfish resource has 

been made with specific reference to the relevant National Policy Statements 

(NPS). These are the principal decision making documents for Nationally 

Significant Infrastructure Projects (NSIP). Those relevant to GWF are: 

� Overarching NPS for Energy (EN-1); and 

� NPS for Renewable Energy Infrastructure (EN-3). 

13.2.1 The following paragraphs provide detail from sections of the relevant National 

Policy Statements (NPS) (July 2011) EN-1 and EN-3 that are considered of 

relevance to the assessment of impacts on the fish and shellfish resource. 

13.2.2 The specific assessment requirements relating to fish and shellfish resource, 

as detailed within the NPSs, are repeated in the following paragraphs. 

Where any part of the NPS guidance has not been followed within this 

assessment, it is stated after the NPS text and a justification provided. In all 

other cases the assessment requirements suggested within the NPSs have 

been applied to this assessment. 


Final Report Chapter 13 - Page 1 October 2011

13.2.3 Section 5.3 of EN-1 sets out the policy for the IPC in relation to generic 

biodiversity impacts and paragraphs 2.6.58 to 2.6.71 of EN-3 set out offshore 

wind-specific biodiversity policy (see Section 5.3.3). In addition, there are 

specific considerations which apply to the effect of offshore wind energy 

infrastructure proposals on fish as set out below. 

13.2.4 Paragraph 2.6.73 states that: 

13.2.5 “There is the potential for the construction and decommissioning phases, 

including activities occurring both above and below the seabed, to interact 

with seabed sediments and therefore have the potential to impact fish 

communities, migration routes, spawning activities and nursery areas of 

particular species. In addition, there are potential noise impacts, which could 

affect fish during construction and decommissioning and to a lesser extent 

during operation.” (Sections 13.6, 13.7 and 13.8). 

13.2.6 Paragraph 2.6.74 states that: 

13.2.7 “The applicant should identify fish species that are the most likely receptors 

of impacts with respect to: 

� feeding areas; 

� spawning grounds; 

� nursery grounds; and 

� migration routes.” (Section 13.4) 

13.2.8 In addition, paragraphs 2.6.75, 2.6.76 and 2.6.77 also discuss mitigation 

measures for reducing electromagnetic field (EMF) effects as well as for 

reducing the overall impacts of construction on fish communities. (Section 

13.7). 

13.2.9 The following guidance documents have also been used during the 

assessment of marine and intertidal ecology impacts: 

� Guidance on the Assessment of Effects on the Environment and 

Cultural Heritage from Marine Renewable Developments (Produced 

by: the Marine Management Organisation (MMO), the Joint Nature 

Conservation Committee (JNCC), Natural England, Countryside 

Council for Wales (CCW) and the Centre for Environment Fisheries 

and Aquaculture Science (Cefas), December 2010); and 

� Guidelines for data acquisition to support marine environmental 

assessments of offshore renewable energy projects. Draft for 

Consultation issued 10th March 2011. Cefas contract report: ME5403 

– Module 15. 

� Offshore wind-farms: guidance notes for EIA in respect of FEPA and 

CPA requirements. Prepared by the Centre for Environment, Fisheries 

and Aquaculture Science (Cefas) on behalf of the Marine Consents 

and Environment Unit (MCEU). Version 2 – June 2004 



13.2.10 The implications of the following regulations and legislation have been taken 

into consideration when writing this ES: 

� Offshore Marine Conservation (Natural Habitats, &c.) Regulations 

2007; 

� Conservation of Habitats and Species Regulations 2010 (“Habitats 

Regulations”); and 

� Wildlife and Countryside Act 1981. 

Consultation 

13.2.11 As part of ongoing consultation, key stakeholders were invited to respond to 

a scoping document produced as part of the EIA process (GWFL, 2010). 

Table 13.1 summarises issues that were highlighted by the consultees in the 

IPC Scoping Opinion (IPC, 2010) and indicates which sections of the 

assessment address each issue. GWFL undertook early consultation with 

Cefas on the requirement for, and scope of, site specific surveys to 

characterise the fish and shellfish baseline environment. 

13.2.12 Further consultation was undertaken through formal Section 42 consultation 

under the Planning Act 2008 (see Chapter 7 Consultation) via the 

submission of a Preliminary Environmental Report (PER). Community 

consultation under Section 47 has also been carried out in parallel with the 

Section 42 statutory consultation. The process for GWFL’s community 

consultation is set out in the Statement of Community Consultation (SoCC) 

for GWF (see Chapter 7). Full details of responses received are presented 

in the IPC Scoping Opinion report (IPC, 2010) and the Consultation Report 

that accompanies the Development Consent Order (DCO) for this 

application. 

Table 13.1 Summary of consultation and issues 

Date Consultee Summary of issue Section 

where 

addressed 

September 

2009 

September 

2009 

Kent and Essex 

Sea Fisheries 

Committee 

Shark Trust and 

inshore fishermen 

Concerns relating to spawning 

species including sole, sandeel, 

herring and also egg laying species 

such as rays and dogfish which are 

thought to lay their eggs in the 

deeper water between the Gabbard 

and Galloper banks. 

The proposed GWF area is known as 

an important local pupping ground for 

spurdog. Consideration required of 

Section 13.6 

Section 13.6 



Date Consultee Summary of issue 

spurdog, and other elasmobranchs, 

especially egg laying species. 

Section 

where 

addressed 

August 

2010 

August 

2010 

August 

2010 

IPC & Marine 

Management 

Organisation 

(MMO) & Centre 

for Environment, 

Fisheries and 

Aquaculture 

Science (Cefas) 

(Scoping Opinion) 

Eastern Sea 

Fisheries Joint 

Committee 


Joint Nature 

Conservation 

Committee 

(JNCC) & Natural 

England (Scoping 

Opinion) 

Operational noise & vibration on fish 

is not scoped out. 

The Commission recommends that 

the impacts on protected fish species 

is fully assessed and mitigation 

provided. 

Noise and vibration levels along the 

foreshore potentially affecting fish 

should be also be addressed. 

Consideration should be given to 

potential impacts on spawning cod. 

Pile driving restrictions are likely, with 

plaice, herring and sole seen as key 

species. 

Mitigation for effects of suspended 

sediment on fish species should be 

considered e.g. timing cabling 

operations to avoid sensitive periods. 

The effects of EMF should be 

considered. 

Cumulative effects on fish resources 

of the proposed works with the 

Greater Gabbard OWF and the 

proposed East Anglia ONE OWF. 

Key consideration for EIA include 

suspended sediment impacts on 

Spurdog pupping ground. 

Section 13.7 

Section 13.6 

Section 13.6 

Section 13.6 

Section 13.6, 

13.7 and 13.10 

Section 13.6 

August Royal Society for Any impacts on the early life stages Section 13.7 




where 

addressed 

2010 the Protection of of fish may have lethal effects for bird 

Birds (RSPB) 


life. 

July 2011 Suffolk Coast and 

Heaths AONB 

Unit and Suffolk 

County Council 

and Suffolk 

Coastal District 

Council (Section 

42) 

July 2011 

MMO (Section 42) 

Consideration should be given to use 

of artificial reefs along the cable and 

within the wind farm to mitigate 

impacts. 

Clarification on GWF site specific 

fisheries survey data analysis, 

surveyed area and specification of 

survey methodology. 

Ideally modelling of noise impacts on 

the critically endangered eel would 

have been undertaken. This could be 

added to the EIA. 

Present data to support the 

statement that the main Downs 

herring spawning grounds are in the 

eastern English Channel and that the 

Southern Bight spawning grounds 

are of less importance. 

Consideration of the impact of noise 

on herring eggs. 

Use of most recent up-to-date ICES 

advice on status of elasmobranch 

stocks. 

Piling construction: Potential to install 

all monopiles during a 10 week 

period thereby avoiding sensitive 

periods of herring and sole. 

Section 13.7. 

Section 13.3 

and Technical 

Appendix 

13.A 

Section 13.6 

Section 13.4, 

13.6 and 

Technical 

Appendix 

13.C 

Section 13.4 

Section 13.4 

and 13.6 




where 

addressed 

July 2011 

East Anglia 

Offshore Wind 

Limited (EAOW) 

A condition must be included in the 

DCO stating that no piling may occur 

from 1st November to 31st May. 

Fleeing speeds of fish in relation to 

piling. 

Consideration of background noise 

levels in EIA. 

Consideration of particle motion 

impacts on hearing insensitive 

species such as sole. 

Cumulative impacts to sole spawning 

should be fully considered in the EIA. 

Consideration of sediment type in 

INSPIRE V18 sound propagation 

model. 

Use of dBht species metric rather than 

the more widely used M-weighted 

sound exposure level makes 

comparisons and practical 

implications difficult. 

Clarification is required on what 

parameters are used to derive 

regional significance for species 

selected for noise modelling. 

Insufficient consideration regarding 

the cumulative impact of repeated 

hammer blows necessary to erect 

each foundation and the knock-on 

effect that this evokes on impact 

range maps. 

Cumulative impact of underwater 

noise with EAOW construction 

programme. 

Section 13.6 

Section 13.6 

Section 13.6 

Section 13.10 

Technical 

Appendix 

13.B 

Section 13.6 

Section 13.6 

and Technical 

Appendix 

13.B 

Section 13.10 

and Technical 

Appendix 

13.B 

Section 13.10 



Date Consultee 

(Section 42) 

Summary of issue Section 

where 

addressed 

July 2011 

July 2011 

July, 

August 

2011 

13.3 Methodology 

Study area 

Dutch Fisheries 

Organisation 

(Section 42) 

Aldeburgh local 

fishermen, 

Aldeburgh 

Fishermens Trade 

and Guild and 

Eastern Inshore 

Fisheries and 

Conversation 

Authority (Section 

47) 

Eastern Inshore 

Fisheries and 

Conservation 

Authority (EIFCA) 

(Section 42) 

Effects of underwater sound on fish 

and impacts on fish larvae. 

ES should address construction and 

operational noise, EMF, impacts on 

local fish stocks, creation of artificial 

habitat as mitigation. 

Monitoring should consider GWF in 

isolation and cumulative needs. 

Suggest monitoring to establish the 

effects of EMF. EMF is one of key 

reasons that the Authority maintains 

a general objection to offshore wind 

farm development. 

Cumulative EMF impacts associated 

with GWF and East Anglia ONE 

cable crossing points of export 

cables. 

Section 13.6 

and Technical 

Appendix 

13.B 

Section 13.6 

and 13.7 

Section 13.11 

Section 13.7, 

13.10 

13.3.1 The study location with regard to natural fish and shellfish resources is 

considered to encompass the proposed GWF, export cable corridor and the 

wider Outer Thames area, in particular ICES rectangles 32F2, 32F1, 33F2 

and 33F1. With regard to fish species and given their highly mobile nature in 

some cases it is necessary to consider the status of fish stocks in the context 

of wider regional dynamics across the southern North Sea and also the 

English Channel. The relation of these ICES rectangles and the Thames 

Strategic Environmental Assessment (SEA) are shown in Figure 13.1. 





Characterisation of the existing environment 

13.3.2 Existing data sources that enable a detailed broadscale characterisation of 

the natural fish and shellfish resource are extensive. Some of these wider 

data sources and studies encompass the proposed GWF study area (e.g. 

Marine Aggregate Levy Sustainability Fund (MALSF), 2009) and, therefore, 

also serve to augment site specific data and knowledge. Those data sources 

and studies that are considered of relevance to the proposed GWF project 

include: 

� Environmental Statements (ES’s) from other offshore wind farm 

developments and aggregates dredging sites; 

� MMO fisheries landings data on commercially important fish species; 

� Department of Environment Food and Rural Affairs (Defra) spawning 

and nursery maps for mobile species considered to be of conservation 

importance (Cefas, 2010a); 

� Fisheries sensitivity maps (Coull et al., 1998); 

� The Outer Thames Estuary Regional Environmental Characterisation 

(MALSF, 2009); 

� Information on species of conservation interest (JNCC); 

� Cefas Interactive Spatial Explorer and Administrator (iSEA), research 

publications and broad scale survey data; e.g. North Sea young fish 

survey (Aug-Sept) / Eastern English Channel survey (Aug-Sept), all of 

which cover some of the Greater Gabbard Offshore Wind Farm 

(GGOWF) and proposed GWF areas; 

� Kent and Essex Sea Fisheries Committee (KESFC) District Research 

Reports; 

� Eastern Sea Fisheries Joint Committee (ESFJC) Research Reports; 

and 

� International Council for the Exploration of the Sea (ICES) Reports 

and Research Publications. 

13.3.3 Further information on the distribution and abundance of fish and shellfish 

species within the general area of the development was obtained from: 

� Monitoring and surveys carried out as part of the GGOWF Food and 

Environment Protection Act (FEPA) licence (Licence 33097/07/0) 

including pre and post construction surveys for: 

o Annual fisheries surveys 

o Noise and Vibration monitoring during piling 

13.3.4 Site specific information has been obtained from dedicated beam and otter 

trawl surveys carried out in the spring and autumn to target adult and juvenile 

fish within the proposed GWF site, export cable corridor and their immediate 

environs (Brown & May Marine Ltd. October 2008 and April 2009). The 



methodologies associated with this survey are summarised in the following 

paragraphs with full detailed accounts of survey methodology and findings 

provided in Technical Appendix 13.A. It is noted that these surveys were 

commissioned in 2009 prior to the site boundary having undergone 

modification (see Chapter 6 Site Selection and Alternatives). Therefore, a 

number of the sample locations that were within the original project boundary 

now lie outwith of its refined extents. 

13.3.5 These sources are considered to be comprehensive in describing the fish 

and shellfish resource that has the potential to be impacted as a result of the 

proposed development of GWF. 

GWF Survey strategy 

13.3.6 GWFL commissioned Brown and May Marine Ltd. to undertake site specific 

fisheries surveys during the autumn (October) of 2008 and spring (April) of 

2009 to characterise the species assemblages within the proposed GWF site. 

13.3.7 The surveys were conducted using a standard commercial otter trawl, fitted 

with ‘rock-hopper’ ground line and 100mm mesh cod end. Tows were limited 

to approximately 25 minutes duration and undertaken during daylight hours. 

The durations of the tows were timed to accommodate the ground conditions 

and the catch rates, as agreed with Cefas. 

13.3.8 A two-metre scientific beam trawl fitted with a 5mm mesh cod-end liner was 

used for the juvenile fish / epibenthic sampling. Beam trawls were 

approximately five minutes in duration. 

13.3.9 A complete description of the survey specifications, methods used including 

boat and gear descriptions, tow speeds, gear deployment locations, dates 

and haul and shot times are presented in the survey reports presented in 

Technical Appendix 13.A. 

13.3.10 Fish and shellfish samples were identified, measured and recorded and data 

standardised to catch per unit effort (CPUE) to account for sampling intensity 

in the three different areas. The survey methodology, including trawl 

locations, gear types and data analysis was agreed through consultation with 

Cefas (Section 13.2) prior to commencement. 

13.3.11 The locations of the commercial otter trawls and scientific beam trawls in 

relation to GGOWF and the proposed GWF site are presented in Figure 

13.2, which shows the sites surveyed during both the autumn (2008) and 

spring (2009) surveys and also the locations sampled during the GGOWF 

surveys. Both otter trawl and beam trawl surveys were carried out for the 

proposed GWF site at the locations labelled B01-B18 in blue on Figure 13.2. 

13.3.12 The locations of the 2m beam trawls, carried out for the 2007 Outer Thames 

Regional Environmental Characterisation, are presented in Figure 13.3. 







Assessment of impacts 

13.3.13 The impact assessment has been undertaken in accordance with the 

methodology set out in Chapter 4 EIA Process. The development envelope 

provided in Chapter 5 Project Details, have been used to establish a 

realistic worst case development scenario for the assessment of impacts. 

The worst case scenario for impacts on fish and shellfish varies depending 

on the impact source under consideration. Therefore, the worst case 

scenario is set out in Section 13.5 and assessed within the specific sections 

of the impact assessment (Section 13.6, 13.7 and 13.8). 

13.3.14 The impact assessment has been informed by dedicated studies, such as 

underwater noise modelling (Subacoustech, 2011 as provided in Technical 

Appendix 13.B) and herring spawning larval data investigations (Technical 

Appendix 13.C) as well as industry experience from monitoring studies 

associated with existing projects (of particular relevance being the knowledge 

gained from the ongoing monitoring studies at the adjacent GGOWF project 

(GGOWL, 2009)). These data are further supported by industry wide studies 

and Collaborative Offshore Wind Research into the Environment (COWRIE) 

publications including the following: 

� Effects of offshore wind farm noise (Thomsen et al., 2006); 

� The effects of pile-driving noise on the behaviour of marine fish 

(Mueller-Blenkle et al., 2010); and 

� A review of the effects of EMF on sensitive marine species (Gill & 

Bartlett, 2010, Gill et al., 2005). 

13.3.15 Other Chapters within this ES (such as Chapter 12 Marine and Intertidal 

Ecology, Chapter 15 Commercial Fisheries, Chapter 14 Marine 

Mammals and Chapter 9 Physical Environment) have been used to inform 

the assessment where inter-relationships are relevant. 

13.4 Existing Environment 

Seabed habitats 

13.4.1 Distribution patterns of fish depend to some degree on the spatial extent of 

appropriate habitat. Over broad spatial areas, the main abiotic factors that 

affect the distribution of fishes and fish communities are water temperature, 

salinity, depth and substrate type. Other features including biotic factors 

(predator-prey interactions, competition, local-scale habitat features) and 

anthropogenic activities (e.g. the presence of artificial structures and 

fisheries) can also be important factors operating on a variety of temporal 

and spatial scales (ICES, 2010a). 

13.4.2 The study area is characterised by shallow water depths principally between 

20m and 40m with sediments comprising medium to coarse sand with silt 

and clay and mixed sediments with areas of patchy cobbles and gravel on 

the banks to the east. The benthic habitats associated with these mobile 

substrates were generally of lower taxonomic diversity and dominated by 



polychaetes. Epibenthic faunal composition was characterised by 

echinoderms and crustaceans, with sparse but diverse mollusc assemblages 

(Chapter 12). 

Broadscale fish species descriptions 

13.4.3 In order to gain an understanding of the relative importance, presence and 

abundance of fish and shellfish species at regional and local levels, 

commercial landings data for ICES rectangles 32F2, 32F1 and 33F1 from 

2006 to 2010 were interrogated to establish which species are regularly 

landed. Although it must be understood that the quantities of species landed 

are often driven by market forces and quota restrictions, assessing landings 

data helps provide context for the site specific fisheries surveys carried out. 

13.4.4 The top 10 species of fish, crustaceans, molluscs and bivalves commonly 

targeted commercially in ICES rectangles 32F2 (main GWF site), 33F1 

(export cable corridor) and 32F1 by weight are presented in Table 13.2. A 

full list of recorded species from both commercial landings data and site 

specific surveys is presented in Table 13.3. 

Table 13.2 Species landings data (tonnes) for the top 15 species landed 2006 – 2010 

from ICES rectangles 32F1, 32F2 and 33F1 

Species Scientific name 

Landings (tonnes) 

32F1 32F2 33F1 Total 

Cockle Cerastoderma edule 2867 - - 2867 

Horse Mackerel Trachurus trachurus 1015 1054 0 2069 

Sole Solea solea 606 89 336 1031 

Cod Gadus morhua 375 35 509 920 

Skates & Rays Raja spp. 410 14 258 682 

Sprat Sprattus sprattus 265 0 107 372 

Plaice Pleuronectes platessa - 176 - 176 

Bass Dicentrarchus labrax 112 - 33 145 

Herring Clupea harengus 28 41 25 93 

Lobster Homarus gammarus 57 - 25 82 

Flounder Platichyths flesus - 10 29 39 

Whelk Buccinum undatum - 38 - 38 

Brown Crab Cancer pagurus - - 37 37 

Mullet - Other Mugilidae 27 - - 27 



Species Scientific name 

Landings (tonnes) 

32F1 32F2 33F1 Total 

Smoothhound Mustelus mustelus - - 20 20 

Dab Limanda limanda - 12 - 12 

Whiting Merlangius merlangus - 11 - 11 

Source: MMO, 2011 

13.4.5 Landings data indicates that the regional study area is more important for 

finfish than shellfish, although brown crab Cancer pagurus, lobster Homarus 

gammarus and whelk Buccinum undatum landings are recorded from all 

three ICES rectangles (Table 13.2). The following finfish species are 

particularly important in the area: horse mackerel Trachurus trachurus, sole 

Solea solea, cod Gadus morhua, skates and rays Rajidae spp., sprat 

Sprattus sprattus, plaice Pleuronectes platessa and bass Dicentrarchus 

labrax (Table 13.2). 

13.4.6 The English Channel is generally considered to represent a biogeographical 

boundary between the northerly boreal province, and the more southerly 

Lusitanean province (Dinter, 2001). Although many boreal species are 

widespread throughout much of the North Sea (e.g. cod and herring Clupea 

harengus), several of the Lusitanian species that are largely restricted to the 

Southern Bight such as lesser weever Echiichthys vipera, greater weever 

Trachinus draco and striped red mullet Mullus surmuletus. 

13.4.7 The key species recorded at the proposed GWF site as identified from 

landings and site specific surveys are listed in Table 13.3. 



Table 13.3 Fish species present within the study area as identified from landings data and site specific surveys 

Common Name Scientific Name Common Name Scientific Name 

Marine Finfish 

Anchovy Engraulis encrasicolus Lumpfish Cyclopterus lumpus 

Bass Dicentrarchus labrax Mackerel Scomber scombrus 

Black Seabream Spondyliosoma cantharus Megrim Lepidorhombus whiffiagonis 

Bib Trisopterus luscus Monks or Anglers Lophius piscatorius 

Brill Scophthalmus rhombus Mullet - Other Mugilidae 

Blonde Ray Raja brachyura Pilchards Sardina pilchardus 

Cod Gadus morhua Plaice Pleuronectes platessa 

Conger Eel Conger conger Pollack Pollachius pollachius 

Common Dragonet Callionymus lyra Poor Cod Trisopterus minutus 

Dab Limanda limanda Red Gurnard Aspitrigla cuculus 

Dover Sole Solea solea Red Seabream Pagellus bogaraveo 

Dragonet Callionymus lyra Red Mullet Mullus surmuletus 

Eelpout Zoarcidae Saithe Pollachius Virens 

Eels Anguilla anguilla Sand Smelt Atherina presbyter 




Flounder Platichyths flesus Sand Sole Pegusa lascaris 

Garfish Belone belone Sprat Sprattus sprattus 

Greater Weever Trachinus draco Squid Unidentified 

Grey Gurnard Eutrigla gurnardus Streaked Gurnard Chelidonichthys lastoviza 

Haddock Melanogrammus aeglefinus Sole Solea solea 

Hake Merluccius merluccius Triggerfish Balistes capriscus 

Herring Clupea harengus Tub Gurnard Chelidonichthys lucernus 

Horse Mackerel Trachurus trachurus Turbot Psetta maxima 

John Dory Zeus faber Twaite Shad Alosa fallax 

Lemon Sole Microstomus kitt Whiting Merlangius merlangus 

Lesser Weever Echiichthys vipera Witch Glyptocephalus cynoglossus 

Ling Molva molva Wrasses Labridae 

Shellfish 

Edible Crab Cancer pagarus Velvet Crab Necora puber 

Lobster Homarus gammarus 

Elasmobranchs 




Blonde Ray Raja brachyura Starry Smoothhound Mustelus asterias 

Lesser Spotted Dogfish Scyliorhinus canicula Thresher Shark Alopias vulpinus 

Smoothhound Mustelus mustelus Thornback Ray Raja clavata 

Spotted Ray Raja montagui Tope Galeorhinus galeus 

Spurdog Squalus acanthias 

N.B. species in bold text are those recorded during the site specific fisheries surveys 



Principal fish species: distribution, spawning and nursery areas 

13.4.8 A number of species of commercial importance are known to use the Outer 

Thames Estuary for spawning and as nursery grounds. Figures 13.4 to 

13.17 show commercially important species which have spawning and 

nursery grounds in the wider Outer Thames Estuary. Table 13.4 identifies 

the main periods of spawning activity for commercial fish species in the Outer 

Thames Estuary and southern North Sea. Further species specific 

information is discussed subsequently for species which are deemed to be of 

particular relevance to the site. 

Table 13.4 Main periods of spawning activity for key fish species in the Outer Thames 

region (spawning periods are highlighted in yellow, peak spawning 

periods marked orange) adapted from Coull et al., (1998) 

Sole 

Lemon Sole 

Herring * 

Herring ** 

Sandeel 

Plaice 

Cod 

Whiting 

Mackerel 

Sprat 

Bass 

Edible crab 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Herring: * refers to the Downs autumn Channel herring, ** refers to the Thames (or Blackwater) spring 

spawning herring 

13.4.9 Information on the spawning and nursery grounds of commercially important 

species (Cefas, 2010a, Coull et al., 1998) that overlap or are in close 

proximity to the study area or are considered to be sensitive to potential wind 

farm impacts (e.g. elasmobranchs and herring) are discussed by species 

below. 

Individual fish species accounts - finfish 

Herring 

13.4.10 Herring are a commercially important pelagic fish, common to much of the 

North Sea. Herring deposit their eggs on a variety of substrates from coarse 



sand and gravel to shell fragments and macrophytes; although gravel 

substrates have been suggested as their preferred spawning habitat. Once 

spawned, herring eggs take about three weeks to hatch, depending on sea 

temperature, after which larvae drift in the plankton. 

13.4.11 While a proportion of the proposed GWF site overlaps with the herring 

spawning grounds (Figure 13.4) the benthic grab (97 stations) and dropdown 

camera surveys (98 stations) concluded that the majority of sediment 

throughout the GWF survey area were poorly sorted and did not offer ideal 

conditions for herring to spawn on (CMACS, 2010, see Technical Appendix 

12.A). 

13.4.12 North Sea herring fall into a number of different ‘races’, each with different 

spawning grounds, migration routes and nursery areas (Coull et al.,1998). 

There are three major races of autumn spawners, which mix on the feeding 

grounds for the majority of the year, but then migrate to specific grounds to 

spawn. As shown in Figure 13.4 the proposed GWF site is located on the 

outer edge of a stock known as ‘the Downs herring’, which spawn in the 

Southern Bight and eastern English Channel from November to January, 

defined by Coull et al., (1998) and more recently updated in Cefas (2010a). 

The other two herring races lie off northeast Scotland and north-east England 

and undergo autumn spawning (taking place from August to September, and 

August to October respectively). These three races represent the bulk of the 

North Sea herring stock, although some spawning also occurs in spring (e.g. 

the Thames Estuary stocks) between mid February to late April. The 

principal recognised spawning sites for the Thames spring spawning herring 

are the Eagle Bank, at the mouth of the Blackwater Estuary and Herne Bay 

(Wood, 1981) with both of these spawning grounds being located 

approximately 55km from the proposed GWF site. 

13.4.13 The use of the Thames Estuary by herring is generally seasonal, with the 

inshore migrations of the Blackwater herring starting in early October with 

fish concentrating within 10 miles of the East Anglian coast in preparation for 

spawning the following spring (Wood, 1981 as cited in Fox, 2001). Juveniles 

generally spend two years in coastal areas before moving offshore to join the 

adult stock (MacKenzie, 1985, cited in ICES, 2010a). 

13.4.14 The Southern Bight spawning ground covers an area of approximately 

3,300km 2 with the two East Channel Downs herring spawning sites (based 

on the Coull et al., 1998 data) covering areas of 1,300km 2 and 1,500km 2 

respectively. The latter two sites are located approximately 160km and 

260km to the southwest of the proposed GWF site respectively. 

13.4.15 Herring have a relatively high sensitivity to underwater sound and vibration 

due to their physiology and extension of the swim bladder (bulla) that 

terminates within the inner ear. Herring spawning and nursery areas are, 

therefore, particularly sensitive and vulnerable to anthropogenic influences, 

especially given that herring are a benthic spawning species. 



13.4.16 In light of the comments raised during consultation (see Table 13.1) it was 

recognised that better resolution of the spawning grounds currently used by 

the Downs herring was required in order to establish the extent of potential 

noise related impacts. Larval data from the International Herring Larvae 

Survey (IHLS) was acquired for the years 2000 to 2011 (see Appendix 

13.C). Herring larval data, especially for newly hatched yolk-sac larvae, is 

widely used to indicate herring spawning activity and define the spawning 

grounds currently being used. 

13.4.17 It is widely acknowledged that since the 1970’s the main Downs herring 

spawning grounds have been confined to the Eastern English Channel 

(Dickey-Collas et al., 2009, Pawson, 1995, ECA and RPS Energy, 2010, 

Rohlf & Gröger, 2003) and that the herring larvae recorded in the Southern 

Bight originate from spawning grounds in the Eastern Channel (C Van 

Damme 2011, pers. comm. 12 August). This is also reflected by the 

commercial exploitation of the Downs stock where winter spawning 

aggregations are targeted by fleets in the eastern English Channel (ICES, 

2009, ICES, 2007a). 

13.4.18 Maps of the larval data indicate that in agreement with previous studies the 

centres of newly hatched yolk-sac larvae evident in December centre on the 

eastern English Channel Downs herring spawning grounds with only limited 

spawning activity occurring on the Southern Bight spawning grounds (see 

Technical Appendix 13.C and Figure 13.5). IHLS surveys are undertaken 

in December and January to capture the Downs herring spawning activity. 

The presence of non yolk-sac larvae in the Southern Bight by the January 

surveys is as a result of passive transport whereby larvae originating from the 

eastern English Channel are transported to their nursery grounds in the 

southern North Sea by the regional hydrodynamic regime and meteorological 

forcing. This trend is clearly demonstrated by the 2010/2011 data presented 

in Figure 13.5 which shows that following the December survey the larvae 

disperse and are subsequently transported into the southern North Sea by 

the by the time of the mid and end of January surveys. This transport of 

eggs and larvae is also well documented for a number of other species with 

spawning grounds in the eastern English Channel (see Erftemeijer et al., 

2009, Dickey-Collas et al., 2009, Houghton & Harding, 1976). 

13.4.19 The data indicates that while a proportion of the proposed GWF site lies 

within areas shown by Coull et al.,(1998) to be part of the Downs Southern 

Bight Downs spawning grounds, these grounds are not currently used as the 

main spawning grounds which are currently located in the English Channel. 

13.4.20 It has been suggested that the importance of spawning grounds for herring in 

the North Sea is related to the health of the stock (Schmidt et al., 2009) and 

some historic spawning grounds which currently have no or very little activity 

can be “re-colonised” over time (e.g. Corten, 1999). Whilst we must 

acknowledge that the Southern Bight grounds may be re-colonised in the 

foreseeable future, based on current trends they are at present not used by 

the main Downs spawning stock. 







Cod 

13.4.21 Cod Gadus morhua is widely distributed throughout the North Sea. Adult cod 

(+70cm) densities tend to be highest in the north, between Shetland and 

Norway, along the edge of the Norwegian Deep, in the Kattegat off the 

Danish coast, around the Dogger Bank and in the Southern Bight. Subadults 

(



Whiting 

13.4.26 Whiting Merlangius merlangus is widely distributed throughout the North Sea, 

Skagerrak and Kattegat off the Danish coast. High densities of both small 

and large whiting may be found almost everywhere, with the exception of the 

Dogger Bank, which generally shows a marked hole in the distribution (ICES, 

2010a). 

13.4.27 Spawning takes place from January in the southern North Sea (Svetnovidov, 

1986). The pelagic eggs, which take about ten days to hatch, are shed in 

numerous batches over a period that may last for up to 14 weeks (ICES, 

2010a). 

13.4.28 During summer, juveniles are particularly abundant in the German Bight and 

off the Dutch coast to the north-east of the proposed GWF site. Large 

whiting occur in high densities south of Shetland during the winter, when 

densities are relatively low in the central North Sea. During summer, the 

entire southern half of the North Sea is densely populated by adult whiting. 

Whiting were also one of the most abundant species caught during the site 

surveys (Plot 13.2, Plot 13.3, Plot 13.4 and Plot 13.5). 

13.4.29 As shown in Figure 13.7 the wind farm site falls within the low intensity 

spawning and nursery areas. Catch rates presented in Figure 13.7 indicate 

that, while GWF falls within the nursery area, higher numbers of juvenile 

whiting tend to be caught in the more northerly parts of the North Sea. 





Plaice 

13.4.30 North Sea plaice Pleuronectes platessa form a stock that consists of a 

number of sub-units and they are commonly found all around the UK and 

Irish coasts, with a preference for sandy substrates, although older age 

groups may be found on coarser sand. 

13.4.31 During the spawning season of December to April, individuals from the subunits 

can be found in an area of the southern North Sea known as the 

‘Southern Bight’. Hunter et al. (2003) demonstrated that, as previous studies 

have shown, the Southern Bight is a major spawning ground for plaice. 

13.4.32 Peak spawning time shifts from early January in the eastern English Channel 

to mid-February in the German Bight and off Flamborough (Rijnsdorp, 1989). 

The duration of the pelagic egg and larval stages of plaice (three to four 

months) is long compared to, for example, sole (about one month) (ICES, 

2010a). This results in long exposures to residual currents, and the young 

plaice may settle in areas far away from the spawning area. While GWF is 

located within an area identified as a high intensity spawning area (Figure 

13.8) the centres of high egg production in the Southern Bight are to the 

southeast and southwest of GWF. Data indicates that commercial plaice 

landings from ICES rectangle 33F2 are higher than from the GWF rectangle 

(32F2) (see Chapter 15), especially during winter (January). This may be a 

reflection of the higher importance of this rectangle and area of the North Sea 

to spawning plaice in comparison to the GWF area. 

13.4.33 Tagging experiments have shown strong fidelity behaviour, with individual 

fish returning to the same spawning and feeding areas (Hunter et al., 2003). 

Part of the North Sea plaice population spawns in the Channel and returns to 

its feeding grounds in the North Sea afterwards. Juveniles are found in 

shallow coastal waters and outer estuaries such as the Thames and as they 

grow older they gradually move into deeper water (“Heinckes Law”) (ICES, 

2010a). 

13.4.34 Plaice represent an important commercial species landed from rectangle 

32F2, in keeping with the well documented importance of the southern North 

Sea for this species (see Chapter 15). Plaice were also caught at the GWF 

site during the otter and 2m beam trawl surveys. 

13.4.35 Due to the lack of a swimbladder, it is thought that flatfish species such as 

plaice tend to be less sensitive to noise than roundfish. 





Sole 

13.4.36 Sole Solea solea tend to occupy shallow, sandy and sandy / muddy habitats 

and are widespread throughout UK waters. Although such habitats are 

common across much of the North Sea and spawning occurs along all 

southern North Sea coasts, five main spawning grounds can be distinguished 

(see Figure 13.9): 

� Inner German Bight; 

� Belgian coast; 

� Eastern Channel; 

� Thames Estuary; and 

� Norfolk Banks. 

13.4.37 Data from Cefas (2010a) show the Thames Estuary as a high intensity 

spawning area (Figure 13.9). In the Thames mature sole move inshore into 

relatively shallow water often associated with reduced salinity (Burt and 

Milner, 2008). At this time of year sole are densely aggregated with 

spawning taking place within the 30m depth contour. Spawning is triggered 

by sea water temperature, with peak spawning being advanced during a 

warm spring (ICES, 2010a). Sole also show a preference for sandy and finer 

grained sediments during both adult and juvenile stages (Kaiser et al., 1999, 

Rogers, 1992). The stage I sole egg data presented in Figure 13.9 also 

supports the presence of inshore sole spawning occurring inshore in the 

Thames. 

13.4.38 Eastwood and Meaden (2000) modelled the spawning habitat suitability for 

sole in the southern North Sea using the distribution of eggs in relation to 

parameters such as temperature, depth, salinity and sediment type. Clear 

relationships were found between these parameters with consistently higher 

densities of eggs associated with sediment with

13.4.40 Studies of sole larval distribution in the Eastern Channel and Southern Bight 

also found sole larvae to be distributed in coastal waters throughout their 

development (Grioche et al., 2001). The association of sole spawning 

grounds with suitable inshore habitats may be linked to a strategy of having 

the youngest larvae in areas of lower currents, which allows their retention in 

shallow waters with high temperatures and fluorescence (Grioche et al., 

2001). This is also supported by their relatively short pelagic egg and larval 

phase (one month) which generally means offspring never move large 

distances from spawning grounds. Nursery grounds are generally found in 

shallow coastal waters at depths between 5 and 10m, and the local 

abundances of 0-group sole are thought to reflect the spawning success of 

local spawning aggregations (Rogers & Stock, 2001). 

13.4.41 A study in the Thames Estuary found that at different locations and even on 

different days peak spawning took place in the evening (Child et al., 1991). 

Studies on captive sole have also documented complex synchronised 

spawning courtship behaviour (Baynes et al., 1994). Spawning begins in 

March, peaking in April and continuing sporadically until late June (Burt and 

Milner, 2008). The analysis of market sampling data presented in Bromley 

(2003) also indicated that the proportion of males with full testes peaked in 

April, at the same time as the peak in the hyaline egg phase in females. 

These studies would suggest that the key sensitive period for sole spawning 

is April as spawning activity declines rapidly following this peak period. 

13.4.42 Sole migrate to the warmer offshore grounds in autumn when temperatures 

fall. In severe winters, they may form dense aggregations in the deeper and 

less cold parts in the southern North Sea and the eastern Channel (Rijnsdorp 

et al., 1992). In March to May they return to inshore waters. 

13.4.43 Tagging experiments support the suggestion that the spawners return to the 

same spawning grounds year after year, but it is not known whether recruits 

return to the grounds where they were born (Burt and Milner, 2008). 

13.4.44 The proposed GWF site is located just outside the sole nursery area (Figure 

13.9) although the cable corridor passes through a low intensity nursery 

ground. The high intensity nursery areas are located to the west of the 

proposed GWF site (Figure 13.9) and this area represents an important 

nursery area for sole on a UK wide level. 

13.4.45 Sole represent a commercially important target species in the Outer Thames 

Estuary. By weight and also by value (Chapter 15), sole landings represent 

an important proportion of the demersal catches from the ICES rectangles 

associated with the proposed GWF site. Sole were also well represented in 

the fisheries surveys (Plot 13.2 and Plot 13.4). 

13.4.46 As a flatfish species, sole is considered to be relatively insensitive to sound 

as it does not have a swim bladder; however construction noise such as pile 

driving creates high levels of sound pressure and acoustic particle motion in 

the water and seabed which have been shown to induce behavioural 

reactions in sole (Mueller-Blenkle et al., 2010).. 













Lemon Sole 

13.4.47 Lemon sole Microstomus kitt is widely distributed off the coasts of the British 

Isles but is most commonly found in the English Channel and the Irish Sea 

(Barnes, 2008). Lemon sole were caught in both the spring and autumn otter 

trawl surveys in the wind farm, outside the wind farm footprint and export 

cable corridor sites (Plots 13.2 and Plot 13.4). Figure 13.14 indicates that 

the proposed GWF site lies within both the spawning and nursery areas for 

lemon sole as defined by Coull et al., (1998). However, the area covered by 

the wind farm is small in relation to the total areas of the spawning and 

nursery grounds. 

13.4.48 Lemon sole is thought to spawn everywhere it is found (Rogers and Stocks, 

2001), with spawning taking place over a long period (from April to 

September). Eggs and larvae are planktonic, with post-larvae found in the 

mid water before becoming demersal, when reaching 3cm in length 

(Wheeler, 1978). 

Sandeel 

13.4.49 Sandeel Ammodytes marinus have a close association with sandy substrates 

into which they burrow and are largely stationary after settlement. There is a 

complex of local (sub-) stocks in the North Sea. Sandeel favour coarse sand 

with fine to medium gravel and low silt content, avoiding sediment containing 

>4% silt (particle size







Sprat 

13.4.53 IBTS survey data indicates that sprat Sprattus sprattus is most abundant 

south of the Dogger Bank and in the Kattegat, with the distribution extending 

around the British coast. Secondary concentrations are found in the Firth of 

Forth and the Moray Firth (ICES, 2010a). 

13.4.54 Sprat are multiple batch spawners, with females spawning repeatedly 

throughout the spawning season (up to 10 times in some areas) (ICES, 

2010a). Spawning occurs in both coastal and offshore waters, during spring 

and late summer, with peak spawning between May and June, depending on 

water temperature (ICES, 2010a). Spawning generally takes place at night. 

The eggs (0.8-1.3 mm in diameter) and larvae of sprat are pelagic (ICES, 

2010a). 

13.4.55 Sprat represents prey for many commercially important predatory fish, such 

as the larger gadoids, as well as diving seabirds. 

13.4.56 Figure 13.16 indicates that the proposed GWF site lies within the sprat 

spawning grounds. However, these are widespread and extend throughout 

the majority of UK coastal waters. 

Individual fish species accounts - elasmobranchs 

13.4.57 Elasmobranchs are the group of electrosensitive fish that includes sharks, 

rays and skates. A number of these species are protected under the Wildlife 

& Countryside Act 1981 and as species of priority importance under UK and 

individual country Biodiversity Action Plan (BAP) arrangements (see section 

on Species of Conservation Importance Table 13.6 see Page 59). 

13.4.58 Elasmobranchs are particularly vulnerable to overexploitation and globally 

have suffered significant reduction in their numbers due to unregulated 

fishing effort and habitat degradation. Elasmobranch species generally have 

a small number of offspring and long maturation periods meaning that 

populations cannot recruit individuals fast enough to replace those lost 

through fishing or other sources of mortality. Certain species such as angel 

shark Squatina squatina, common skate Dipturus batis and white skate Raja 

alba are now considered to be extinct in large parts of their former range. 

The status of other commercially important species (for example thornback 

ray, Raja clavata, other large Rajids, and spurdog, Squalus acanthias is of 

increasing concern for both fisheries and nature conservation. 

13.4.59 Spotted ray and blonde ray are of lesser importance, and other skate 

species, such as undulate ray Raja undulata and small-eyed ray Raja 

microcellata, are occasional vagrants to this area from the English Channel. 

Cuckoo ray Leucoraja naevus and starry ray Amblyraja radiata occasionally 

occur in the southern North Sea, but the main North Sea stocks of these 

species are further north. 

13.4.60 Elasmobranchs can detect the electrical fields emitted by themselves and 

other organisms. The most widely known use of electric fields is for prey 



detection, where the prey item generates an electric field that the predator 

senses. Electrosensitivity can also be used for orientation. Orientation is 

possible due to the differences in resistivity of objects which enter the 

animal’s electric field. Compass-like navigation is accomplished by 

interpreting the effect of the earth’s electromagnetic currents on the electric 

field created as the animal swims underwater (similar to echolocation used 

by dolphins) (MMO et al., 2010). 

13.4.61 The most abundant elasmobranch species caught during the GWF site 

surveys by number were lesser-spotted dogfish, thornback ray, starry 

smooth-hound and smooth-hound. Other species recorded included spotted 

ray, blonde ray and tope (Plot 13.2 and Plots 13.4). 

13.4.62 Table 13.5 provides a qualitative summary of the general status of the major 

elasmobranch species relevant to the proposed GWF site based on ICES 

2010 advice. The 2011 and 2012 advice on catches for thornback ray, 

lesser-spotted dogfish, smooth hound and starry smooth hound for the 

southern North Sea are to maintain status quo catch (ICES, 2010). 

Table 13.5 Status of demersal elasmobranchs in the North Sea 

Species Scientific name Area State of stock 

Thornback ray Raja clavata IVc, VIId Stable / increasing 

Lesser-spotted dogfish Scyliorhinus canicula IVa,b,c, VIId Increasing 

Smooth hound & 

Starry smooth hound 

Source: ICES Advice (2010) 

Mustelus mustelus & 

Mustelus asterias 

IVa,b,c, VIId Increasing 

13.4.63 Based on their commercial importance, further information for thornback ray 

and spurdog is provided below along with information on tope Galeorhinus 

galeus as the proposed GWF site lies within an area identified as potential 

nursery grounds for tope and also lesser-spotted dogfish. 

Thornback ray 

13.4.64 Thornback ray is the most abundant skate (Rajidae) in the south-western 

North Sea, and the Outer Thames Estuary is considered to be of regional 

importance for the species. Thornback ray is one of the most commercially 

important skate species in UK waters and, in the Thames, can account for 

some 93 – 100% of the skate catch (Ellis et al., 2008). 

13.4.65 Wider studies in the southern and central North Sea by Cefas (ICES, 2007b) 

demonstrate that thornback ray has shown range contraction as the 

population has declined, and that they are now most abundant in the Outer 

Thames Estuary and The Wash (Figure 13.17). 

13.4.66 Rays are particularly vulnerable to exploitation due to their low fecundity, late 

age at maturity and large size at maturity. Survey catch trends in Division 



IVc have been stable / increasing in recent years. The status of thornback 

ray in Divisions IVa,b is uncertain (ICES, 2008). 

13.4.67 Thornback ray aggregate by sex and size, often showing an uneven sex 

ratio, with females dominating the larger size classes. It is evident that 

juvenile thornback ray are widespread in the shallower waters of the Outer 

Thames Estuary and along the English Channel coast of Southern England 

(Ellis et al., 2005), although it is not known whether there are specific 

spawning grounds for thornback ray. Part of the proposed GWF site and the 

export cable corridor lie within a low intensity nursery ground for this species 

(see Figure 13.18). 

13.4.68 Studies of ray movements in the Thames Estuary showed that 96% of rays 

tagged were recaptured there (Hunter et al., 2005), suggesting that these 

rays form distinct sub-populations and exhibit small scale movements. 

These studies also showed that rays were located in water of 20m to 35m 

depth during the autumn and winter, and migrated into shallower water 

(





Spurdog 

13.4.70 Spurdog is one of the more common shark species in the North Sea. At the 

beginning of the 20th Century it was abundant, and often considered a 

nuisance by commercial herring fishermen, as they caused damage to the 

nets and catches. Landings increased rapidly during the late 1950’s and 

early 1960’s, though landings have since declined (ICES, 2010a). 

13.4.71 Spurdog was formerly widespread and abundant throughout most of the 

area, but IBTS survey data indicates it is currently most abundant in the 

western North Sea and off the Orkney and Shetland (ICES, 2010a). Spurdog 

are also caught in the Outer Thames and consultation responses from the 

Shark Trust and inshore fishermen indicate that the GWF area is thought to 

be an important local pupping ground (Table 13.1). Information from local 

fishermen have indicated that a spurdog fishery used to exist between 

February and March to the eastern side of the Outer Gabbard, although in 

recent years a quota restriction and maximum landing size has seen this 

fishery halt (Chapter 15). The spurdog fishery in the North Sea has also 

been closed since 2011 due to the severely depleted nature of the stocks. 

During the site specific surveys only a single (one) spurdog was recorded in 

the otter trawl catches. 

13.4.72 Tagging experiments have shown that spurdog may migrate all around the 

British Isles. Thus, the North Sea component is considered to represent part 

of a much larger stock (ICES, 2010a). Given their complex and widespread 

seasonal migrations and long gestation periods, parturition grounds are hard 

to define (Cefas, 2010). 

13.4.73 Spurdog is aplacentally viviparous, giving birth to live young, with two to 21 

pups born after a gestation period of 22 to 24 months (Holden and Meadows, 

1964; Gauld, 1979; Ellis and Keable, 2008). Young are reliant on yolk 

reserves during embryonic development and fecundity increases with size. 

The size at birth ranges from 19cm to 30cm, though is typically 26-28cm. 

The pupping season is from August to December (ICES, 2010a). 

13.4.74 Juvenile spurdog are widely distributed in the central and northern North Sea, 

North West Scotland and Irish and Celtic Sea (see Figure 13.16). The high 

intensity nursery grounds are situated off west Scotland. The proposed GWF 

site does not lie within any identified nursery grounds (Figure 13.19). The 

apparent absence of juveniles from the eastern English Channel and 

southern North Sea may be an artefact of the sampling and fewer otter trawl 

surveys in the area (Cefas, 2010a). 

13.4.75 A low fecundity, coupled with an extremely low growth rate, makes spurdog 

vulnerable to commercial overexploitation. 





Tope 

13.4.76 Tope is widely distributed in the North-Eastern Atlantic, occurring as far north 

as Norway. In British waters, it is most common in the southern North Sea, 

English Channel, Bristol Channel and Irish Sea (Ellis et al., 2005). It is 

considered to be a single stock of tope in the NE Atlantic. 

13.4.77 Tope are ovoviviparous producing live young. Gestation is thought to last for 

about 12 months, and females move inshore to coastal nursery areas in the 

late summer to give birth. The proposed GWF site is located in an area 

identified as a low intensity nursery area for tope (see Figure 13.20). A 

single juvenile female tope was recorded from GWF during the autumn otter 

trawl survey. 

Lesser-spotted dogfish 

13.4.78 Dogfish are thought to lay their egg cases in the deeper water between the 

Gabbard and Galloper banks and concerns were raised during scoping with 

regards to the disturbance of this egg laying species (Table 13.1). 

13.4.79 Dogfish are widespread in the North-east Atlantic and were one of the most 

abundant elasmobranchs recorded during the site specific surveys (see 

Plots 13.2 to 13.5). They are oviparous, laying 2 eggs at a time, with 

females laying as many as 5/7 eggs per week during the breeding season 

(November to July). The availability of prey and requirement for females to 

have suitable egg-laying substrates are also thought to influence their 

distribution with high abundances often associated with the presence of 

erect, sessile invertebrates (e.g. Flustra spp.) that are important egg-laying 

substrates (Ellis & Shackley, 1997, Kaiser et al., 1999). 





Individual species accounts - shellfish 

13.4.80 While the general GWF areas are acknowledged as being more important for 

finfish than shellfish (MMO, 2010) ICES rectangles 32F1, 32F2 and 33F1 do 

provide catches of shellfish. Landings data indicates high landings of cockle 

Cerastoderma edule from area 32F1. These landings come from the inshore 

Thames cockle fishery which is not within proximity to GWF. Landings of 

brown crab Cancer pagarus, and lobster Homarus gammarus are recorded 

from the inshore area of the export cable corridor (ICES rectangle 33F1) and 

whelk are recorded from the proposed GWF site (ICES rectangle 32F2). The 

latter three species are therefore considered in further detail below. 

Lobster 

13.4.81 Static fishing for European lobster and crab has been recorded from localised 

areas of the inshore export cable route (Chapter 15) and from commercial 

landings data for the area (Table 13.2). Lobsters are anticipated to be 

present at GWF and the export cable corridor on areas of reef or other 

suitable habitat structures such as wrecks. 

13.4.82 Lobsters are usually located in holes on rocky substrate at lower than mean 

low water neaps (sublittoral fringe) to depths of 150m (Holthius, 1991). 

13.4.83 Growth is by moult, which decreases in frequency during the juvenile stages 

until becoming an annual part of the mating, spawning and egg hatching 

cycle. Females can spawn annually or following a bi-annual pattern. 

Reproduction takes place during summer and is linked with the moulting 

cycle (Atema, 1986). After extrusion, the eggs are held on the pleopods for 

approximately another year until hatching the following summer. The first 

few post-hatching weeks are characterised by a pelagic phase usually lasting 

14 to 20 days depending on the water temperature. Lobsters are sedentary 

animals with home ranges varying from 2 to 10km (Bannister et al., 1994). 

Lobsters do not make extensive migrations when berried and hatching takes 

place in spring and early summer on the same grounds (Pawson, 1995). 

Edible crab 

13.4.84 Edible crab is a common and widely distributed species in the UK (Pawson, 

1995). It occurs from the upper inter-tidal zone down to 100m depth. Small 

crabs are rarely caught in offshore areas which suggest that crabs only move 

into deeper water as they grow and approach maturity. They are known to 

undertake extensive migrations at rates of 2-3km per day during migrations 

of up to 200 nautical miles (Pawson, 1995). The main North Sea crab fishery 

is located to the north of the proposed GWF off Flamborough Head and 

south of Dogger Bank. This corresponds with the centres of larval 

abundance in this area. Once hatched crab larvae are planktonic for up to 

approximately 90 days (Pawson, 1995). The principle potting grounds for 

brown crab are in the area of the export cable landfall and just to the south 

(Chapter 15). Brown crab were recorded in low numbers across the 

GGOWF and the edges of the Galloper bank and export cable route during 

the 2004 and 2005 fisheries surveys (GGOWL, 2005). 



Whelk 

13.4.85 Whelks are common in the North Sea and are distributed extensively around 

the UK coastline (Jacklin, 1998). They inhabit mainly muddy gravel or mud 

mixed with shell. Whelks spawn when they reach maturity at approximately 

two to three years of age. Fertilisation occurs in late autumn followed by 

spawning in November (Jacklin, 1998). After four months development, the 

fully formed juveniles emerge from the egg capsules during February to 

March (Jacklin, 1998). 

13.4.86 Landings data (Table 13.2) and review of commercial fishing activities 

(Chapter 15) indicate that whelk are present around the proposed GWF site. 

Site specific surveys 

GWF baseline fish surveys 2008-2009 

13.4.87 Autumn (2008 and spring (2009) fish surveys have been carried out at the 

proposed GWF site. While it should be acknowledged that the boundaries of 

the proposed GWF site have been modified since the original fisheries 

surveys were carried out, the modifications do not have a significant effect on 

the results presented below, which still remain valid for characterising the 

area. In the subsequent plots, the survey areas outside of the proposed 

GWF site have been referred to as ‘control’, the areas within GWF as ‘wind 

farm’ and locations relating to the export cable as ‘cable / cable route’. 

13.4.88 A total of 51 separate fish species were identified from both the otter and 

beam trawls during the spring and autumn survey, of which nine species 

were elasmobranchs. Approximately 45 separate species were recorded 

from within the GWF site, 40 from the control and 30 from the export cable 

corridor. The differences in species diversity between the GWF site, control 

and export cable are a reflection of survey effort and total combined tow 

duration for each area (see Plot 13.1). 

13.4.89 The most abundant species caught during the surveys were whiting, cod, 

lesser spotted dogfish, dab, bib, plaice, thornback ray and starry smoothhound. 

The results from the spring and autumn otter trawl survey are 

discussed below with results including catch per unit effort (CPUE) presented 

in Plot 13.2 and Plot 13.4 and the proportion of species caught at each site 

presented in Plot 13.3 and Plot 13.5. 



Plot 13.1 Increasing trend between species sampled and total combined tow duration 

at each of the sample locations. 

Tow duration (hrs) 

8.0 

7.0 

6.0 

5.0 

4.0 

3.0 

2.0 

1.0 

0.0 

Otter Trawl Total (otter & beam trawl) No species 

wind control cable 

Spring otter trawl survey summary 

13.4.90 A total of 27 fish species were identified from the otter trawls, 24 within the 

GWF site, 12 along the cable route and 23 at control locations. 

13.4.91 Whiting and lesser spotted dogfish were the species caught in greatest 

numbers, followed by dab, cod and thornback ray to a lesser extent. 

13.4.92 Along the cable corridor lesser spotted dogfish, cod and thornback ray were 

the most abundant species found, accounting for 77% of the catch. The 

remaining 33% consisted of low numbers of nine other species (Plot 13.3). 

13.4.93 Within the GWF site the composition of the catch was dominated by whiting, 

dab, lesser spotted dogfish and cod which accounted for 78.5% of the 

individuals caught. Relatively high numbers of thornback ray were also 

found, this species accounting for 5.6% of the catch. The remaining 18 

species were all caught in small numbers (see Technical Appendix 13.A). 

13.4.94 Similarly, at control locations whiting, dab, lesser spotted dogfish and cod 

were the species caught in greatest numbers accounting for 84.2% of the 

catch. 

13.4.95 Cod and whiting were the main species of commercial interest caught during 

the survey while sole comprised only a small proportion of the catches (see 


Final Report Chapter 13 - Page 52 October 2011 

50 

45 

40 

35 

30 

25 

20 

15 

10 

5 

0 

No. species

Plots 13.2 to 13.7). For cod, the majority of fish caught at all sites were 

above minimum landing sizes (MLS) whilst approximately 50% of the whiting 

were below their MLS (see Technical Appendix 13.A). 

13.4.96 In general terms most of the individuals of dab and plaice caught were 

female whilst the majority of lesser spotted dogfish were male. The sex ratio 

for cod, whiting and thornback ray was approximately 50:50. 

13.4.97 The percentage distributions of the species caught are given in Plot 13.2 for 

the export cable corridor, GWF site and control locations respectively. 



Plot 13.2 Individuals caught per hour by species and sampling area during the spring otter trawl survey 



Plot 13.3 Percentage distribution of species caught along the export cable corridor, 

wind farm and control sites during the spring otter trawl survey 



Autumn Otter Trawl survey summary 

13.4.98 A total of 27 species were identified in the otter trawl sampling (21 species 

within the wind farm area, 19 species along the export cable corridor and 18 

species in the control sites). The catch rates, in terms of the number of 

individuals caught per hour, and the total number of individuals caught overall 

are illustrated in Plot 13.4. The relative percentage distributions are 

illustrated and discussed in Plot 13.5. 

13.4.99 Whiting, cod and bib were caught in highest abundances during the otter 

trawl survey with few other species caught in significant numbers (dab, lesser 

spotted dogfish, plaice, starry smooth-hound and poor cod). Other species 

were caught in very low numbers (see Technical Appendix 13.A). 

13.4.100 Whiting and cod were caught in highest numbers in the samples collected at 

the GWF and the control sites. Along the cable corridor, lesser spotted 

dogfish and bib were the most abundant species. However, cod and whiting 

were also caught in high numbers in this area. 

13.4.101 Lesser spotted dogfish, bib, cod and whiting were the most abundant species 

found along the cable corridor, accounting for 66.5% of the catch. Starry 

smooth-hound and dab were also caught in significant numbers, these 

species accounting for 8.9% and 9.8% of the catch respectively. The 

remaining 13 species were caught in low numbers, accounting for only 18.9% 

of the catch (see Technical Appendix 13.A). 

13.4.102 In the proposed GWF site, whiting, cod and bib were the most abundant 

species accounting for 69.8% of the catch. Plaice, poor cod, lesser spotted 

dogfish, dab and tub gurnard were also caught, representing 23% of the 

catch. The remaining 7.2% of the catch was comprised of low numbers of 

individuals from 13 other species. 

13.4.103 In the control sites, whiting was the most abundant species accounting for 

32.0% of the catch. Cod, dab and bib were also abundant in this area, 

accounting for 43.1%. Plaice, poor cod and tub gurnard were also found, 

accounting for 18.1% of the catch, whilst the remaining 6.7% was comprised 

of low numbers of individuals from 11 other species. 

13.4.104 As for the spring survey the majority of the cod caught were above their 

minimum landing size (MLS) with approximately 50% of whiting below MLS. 

The other commercial species caught were generally present in only low 

numbers. 

13.4.105 In general terms the majority of the dab, whiting and plaice caught were 

female whilst the sex ratio for cod was approximately 50:50. The majority of 

lesser spotted dogfish caught were female in the wind farm site and male 

along the cable corridor. 

13.4.106 The only migratory species sampled were three twaite shad Alosa fallax, 

which were caught at the proposed GWF site. 



Plot 13.4 Individuals caught per hour by species and sampling area during the autumn otter trawl survey 



Plot 13.5 Percentage distribution of species caught along the cable route, wind farm 

and control sites during the autumn otter trawl survey 



Shellfish summary 

13.4.107 The most abundant shellfish species found during the otter trawl surveys 

were velvet crab Necora puber, squid Loligo spp., European lobster and 

Edible crab. 

13.4.108 The main crustacean species by number encountered during the spring and 

autumn beam trawl survey were generally shrimp species including C. 

allmani, Gastrosaccus spinifer, Pandalina brevirostris, and Pandalus 

montagui. The main mollusc species were the bivalve Nucula nigra, Abra 

alba and Chlamys opercularis with gastropods such as painted top shell 

Calliostoma zizyphinum and common whelk also regularly recorded. The 

latter two species were also found to be broadly distributed across the area 

during the GGOWF site surveys (GGOWL, 2005). 

Spring 2m beam trawl summary 

13.4.109 During the spring 2m beam trawl survey a total of 24 fish species were 

caught, 19 within the wind farm site, 15 at control locations and 12 along the 

export cable corridor. 

13.4.110 The common dragonet was the most abundant species found along the 

export cable corridor, whilst the lesser sandeel was the most prevalent within 

the GWF site. At control locations, the lesser sandeel and the sand goby 

were the two fish species found in greatest numbers (Plot 13.6). Sole were 

recorded during the survey in low numbers with a total of 7 caught with a 

length range of approximately 16 to 29cm. 

Autumn 2m beam trawl summary 

13.4.111 In the analysis of samples obtained from the autumn beam trawl surveys 23 

fish species were identified. The results of the beam trawl sampling show 

that species from the goby family (Gobiidae) were the most abundant fish 

species found, especially in the GWF site (Plot 13.7). 



Plot 13.6 Spring 2m beam trawl catch as percentage of total catch per site 

Cable Control Wind Farm 

Percentage of total catch per site 

35% 

30% 

25% 

20% 

15% 

10% 

5% 

0% 

Black goby 

Common dragonet 

Dab 

Dover sole 

Greater sandeel 

Lesser spotted dogfish 

Lesser weever 

Northern rockling 

Plaice 

Pogge/ Hooknose 

Poor cod 

Pouting/ Bib 

Raitt's sandeel /Lesser sandeel 

Reticulated dragonet 

Sand goby 

Sandeel family 

Scaldfish 

Smooth sandeel 

Solenette 

Sprat 

Striped sea snail 

Tub gurnard 

Two-spotted clingfish 

Whiting 

Common name 



Plot 13.7 Autumn 2m beam trawl catch as percentage of total catch per site 

Cable Control Wind Farm 

Percentage of total catch per site 

40% 

35% 

30% 

25% 

20% 

15% 

10% 

5% 

0% 

- 

Common dragonet 

Dover sole 

Fivebeard rockling 

Goby family 

Greater sandeel 

Herring family 

Lesser spotted dogfish 

Lesser weever 

Northern rockling 

Norway pout 

Painted goby 

Pogge/ Hooknose 

Poor cod 

Pouting/ Bib 

Raitt's sandeel /Lesser sandeel 

Sand goby 

Scaldfish 

Sprat 

Striped sea snail 

Thickback sole 

Transparent goby 

Whiting 

Common name 



Comparison to GGOWF findings 

13.4.112 Spring and autumn fisheries surveys were carried out in 2004 and 2005 for 

GGOWF using otter trawl and 2m beam trawl survey gear (GGOWL, 2005). 

Based on the survey information available from the GGOWF ES, the species 

of finfish and shellfish recorded were broadly similar to those identified in the 

more recent surveys outlined above. Twenty-two species of demersal fish 

were identified from the 2m beam trawl and otter trawls. 

13.4.113 The 2m beam trawl surveys were dominated by catches of dragonet, gobies, 

and sandeel, which also comprised a large proportion of the catches in the 

GWF surveys (Plot 13.6 and Plot 13.7). Catches in the otter trawl surveys 

were dominated by flatfish species including sole, plaice, dabs and lemon 

sole along with gadoids such as whiting and cod and elasmobranchs 

including lesser spotted dogfish and smoothhound. These species are 

broadly similar to those recorded in the GWF otter trawl surveys (see Plot 

13.2 and Plot 13.4). 

Outer Thames Estuary REC 2m beam trawl surveys 

13.4.114 The Outer Thames Estuary REC study (MALSF, 2009) undertook 20 beam 

trawls (Figure 13.3). These surveys recorded a total of 28 fish species, with 

the principal ones detailed in Plots 13.8 and Plot 13.9. 

Plot 13.8 Relative contributions of species of fish to overall weight of fish caught in 

the 2 m beam trawls (species contributing to >1% are shown). 

Source: MALSF, 2009 



Plot 13.9 Relative contributions of species of fish to the total number of individuals 

caught in the 2 m beam trawls (species contributing to >1% are shown). 

Source: MALSF, 2009 

13.4.115 Juvenile gobies Pomatoschistus spp. were by far the most numerous fish 

recorded and accounted for 57% of the total number of individuals. Sole 

were also relatively numerous, contributing to 7% of the total number of 

individuals, followed bib (3%). However, in terms of weight, sole was the 

largest contributor, accounting for 50% of the total weight of fish caught. 

Thornback ray and lesser spotted dogfish were secondarily important in this 

respect, accounting for 13% and 11% of the overall weight of fish 

respectively. Bib and whiting contributed 8% and 5% respectively. These 

species were also recorded during the GWF surveys. 

Species of conservation importance and migratory species 

13.4.116 The draft guidance for offshore wind farm developments (MMO et al., 2010), 

states that the EIA procedure should address the potential impacts of the 

offshore wind farm construction and operation on fish species of commercial 

interest as well as on species of conservation interest. A number of species 

in UK waters are subject to Species Action Plans (SAP) under the UK BAP, 

including migratory species, such as salmon, and commercially exploited 

marine fish species (MMO et al., 2010). BAPs are plans that have been 

drawn up to encourage the recovery of particular species or habitats in the 

UK. Some of the key species of relevance to GWF which are BAP species 

include elasmobranchs such as spurdog and tope as well as commercially 

important finfish species including cod, herring, plaice, sole, whiting and 

mackerel. Commercially important species such as cod, thornback ray, 

spurdog along with a host of migratory fish and species such as sturgeon 

Acipenser sturio are also on the OSPAR list of threatened or declining 

species. Over 80 different marine species, ranging from seaweeds to 

commercial fish species, are the subject of SAPs (MMO et al., 2010). Of 

particular interest are elasmobranchs (and other electrosensitive species), 

noise sensitive species and a number of migratory species (MMO et al., 

2010). 



13.4.117 The main migratory species of conservation importance which are 

considered to be of relevance to the Thames and GWF are outlined in Table 

13.6. 

Table 13.6 Summary of UK protection legislation for migratory fish species relevant 

to the Thames Estuary and GWF 

Common 

Name 

Shad (allis / 

twaite) 

Legislation: BAP UK 

priority 

Scientific species 

Name 

Alosa alosa / A. 

fallax* 

River lamprey Lampetra 

fluviatilis 

Sea lamprey Petromyzon 

marinus 

Brown / Seatrout 

Salmo trutta ✓ 

Habitats 

Directive 

Conservation 

of Habitats & 

Species 

Regs. 

OSPAR 

✓ ✓ ✓ ✓ 

✓ ✓ ✓ 

✓ ✓ ✓ 

Atlantic salmon Salmo salar ✓ ✓ ✓ ✓ 

European eel Anguilla anguilla ✓ ✓ 

*shad are also protected under the Wildlife & Countryside Act 1981 

Source: JNCC (http://www.jncc.gov.uk/page-3408). OSPAR 

13.4.118 There are a number of species known to migrate through the Thames 

Estuary that may be of conservation interest and of relevance to the GWF 

project. These include diadromous fish such as Atlantic salmon and sea 

trout, river and sea lampreys and two species protected under the Habitats 

Regulations – the allis and twaite shads. Other migratory species such as 

the European eel and smelt are also known to use the Estuary. A general 

indication of when anadromous fishes undertake their migrations is given in 

Table 13.7. 

Salmon 

13.4.119 Salmon Salmo salar are known to migrate through the Thames Estuary and 

could potentially pass in close proximity to GWF. During migrations in 

coastal or offshore waters, salmon spend most of their time within 4m of the 

surface, although frequent diving behaviour may also be observed (Malcolm 

et al., 2010). Salmon spawn in upper reaches of rivers, where they live for 

one to three years before migrating to sea as smolts. At sea, salmon grow 

rapidly and after one to three years return to their natal river to spawn. 



13.4.120 It is thought that salmonids use chemoreceptor clues to locate their natal 

rivers when migrating in coastal waters, although they are also thought to use 

electromagnetic fields (EMF) during offshore migrations. Salmon may, 

therefore, be sensitive to the levels EMF generated from wind farm cables 

during operation. Although salmon do not have a specific connection 

between the swim bladder and the auditory apparatus, studies have shown 

that they respond to low frequency sounds (Gill & Bartlett, 2010). 

13.4.121 Salmon were not recorded during any of the GWF site specific surveys. 

Table 13.7 Timings of migration for anadromous and catadromous fish species (MMO 

et al., 2010) 

Species Timing of upstream migration 

Sea lamprey Move from the sea to estuaries in April / May (2) , spawning 

in May / June (1,2) 

Salmon Spawn late October to early January (1,2) 

Sea-trout Spawn October / February (1) 

Allis shad Move into estuaries in late spring (2) , spawning during 

April-May (1) 

Twaite shad Start upstream migration in April / May (2) , spawning in 

May / June (1,2) 

Common eel Elvers migrate upstream from January to June, with a 

peak in May (2) 

References: (1) Wheeler (1969); (2) Maitland and Campbell (1992) 

N.B. these are generalised times and peak timing of the upstream migration may vary regionally 

Sea-trout 

13.4.122 Sea-trout Salmo trutta are known to migrate through the Thames Estuary and 

could potentially pass in close proximity to GWF. Their life cycle is almost 

identical to that of salmon (Harris & Milner, 2006), but there are two 

significant differences. In contrast to salmon, the majority of sea-trout 

survives spawning and will return to their natal spawning river on numerous 

occasions during their life time. The other significant difference is that they 

do not appear to undertake the same sea migration but remain in coastal 

waters, probably close to their natal river. 

13.4.123 Due to their physiological similarities sea-trout are likely to have similar 

sensitivities to EMF and noise as salmon described above. 

13.4.124 Sea-trout were not recorded during any of the GWF site specific surveys. 



Eels 

13.4.125 The European eel Anguilla anguilla has long been associated with the River 

Thames. Recorded in the Domesday Book, eels continued to be a valuable 

fishery in London well into the 1800’s (Defra, 2010). Monitoring of eels within 

the River Thames has indicated that very few one year old eels are present 

and it has been suggested that most eels may spend their first year in the 

lower estuary (Defra, 2010). 

13.4.126 European eel spawn in the Sargasso Sea and die after spawning. The 

larvae are transported by the Gulf Stream to North Africa and Europe and the 

juvenile eel enter coastal areas and freshwater as glass eel (ICES, 2010c). 

They quickly transform into yellow eel and stay in Europe for five to 15 years 

or more (ICES, 2010c). Growth and age at maturity are linked to regional 

temperature (mature later at colder temperatures) (ICES, 2010c). Mature 

eels (or silver eels, as they are known on their downstream migration) begin 

the downstream spawning migration usually from late spring to winter and 

migrate back to the Sargasso Sea. Although no eels were recorded during 

sampling at GWF, it is possible eels would pass through the site on their 

seaward migrations and also on their return to the coastline as elvers. 

13.4.127 Little specific information relating to the acoustic ability of anguillid eels has 

been found; as they do not appear to possess a specific link between the 

swim bladder and the ear (Popper & Fay, 1993 as cited in Gill & Bartlett, 

2010), they could be regarded as hearing generalists (Nedwell et al., 2003). 

Allis and twaite shad 

13.4.128 While historically the main concentrations of allis and the twaite shad Alosa 

alosa / A. fallax have been in the Severn Estuary they are recorded within the 

Thames Estuary and have also been recorded at the Sizewell powerstation 

near the proposed GWF cable landfall. Three twaite shad were recorded 

during the autumn otter trawl surveys. 

13.4.129 Both shad species are members of the herring family. Shad are marine 

species, entering freshwater to spawn. They occur mainly in shallow coastal 

waters and estuaries, but during the spawning migration adults penetrate well 

upstream in some of the larger European rivers. Both allis and twaite shad 

have declined across Europe and are now absent from many rivers where 

they once flourished and supported thriving fisheries (Maitland & Hatton-Ellis, 

2003). Because of this decline, the allis shad is now given considerable legal 

protection. It is listed in annexes II and V of the EU Habitats and Species 

Directive, Appendix III of the Bern Convention, Schedule V of the Wildlife and 

Countryside Act (1981) and as a Priority Species in the UK Biodiversity 

Action Plan. 

13.4.130 Mature fish that have spent most of their lives in the sea stop feeding and 

move into the estuaries of large rivers, migrating into fresh water during late 

spring (April to June), thus giving the shad the name of 'May Fish' in some 



areas. Male shad migrate upstream first, followed by females one or two 

weeks later (Maitland & Hatton-Ellis, 2003). 

13.4.131 The requirements of shads at sea are very poorly understood, but they 

appear to be mainly coastal and pelagic in habit (Maitland & Hatton-Ellis, 

2003). A suitable estuarine habitat is likely to be very important for shad, 

both for passage of adults and as a nursery ground for juveniles (Maitland & 

Hatton-Ellis, 2003). 

Smelt 

13.4.132 Smelt Osmerus eperlanus are inshore migratory fish widely distributed in 

shallow waters of the continental shelf, but most common close to river 

mouths and in estuaries, especially in the southern North Sea. It is caught 

very occasionally in coastal waters as part of the Cefas groundfish surveys. 

The strongest and most permanent stocks seem to be those associated with 

the larger estuaries (e.g. the Thames), especially where there is a complexity 

of minor or nearby smaller estuaries (Maitland, 2003). None were recorded 

during the GWF surveys. 

State of the stocks - teleosts 

13.4.133 The depletion of fish stocks through overfishing in the North Sea, has been, 

and continues to be of concern. A summary of the state of North Sea stocks 

(ICES Sub Area IV) of finfish species relevant to the GWF site is given in 

Table 13.8. As is apparent, fishing mortality continues to be a significant 

threat to fish stocks. 

Table 13.8 State of the stocks (ICES, 2009) 

North Sea 

Stock 

Species 

Herring* 

Sole 

Spawning 

biomass in 

relation to 

precautionary 

limits 

Fishing 

mortality in 

relation to 

precautionary 

limits 

Increased risk Harvested 

sustainably 

Full reproductive 

capacity 

Plaice Full reproductive 

capacity 

Harvested 

Sustainably 

Harvested 

sustainably 

Fishing 

mortality in 

relation to 

high long term 

yield 

Fishing 

mortality in 

relation to 

agreed 

management 

target 

Overfished Above target 

Appropriate Above target 

Overfished Below target 

Whiting Undefined Undefined Undefined NA 

Cod Reduced 

reproductive 

Increased risk Overfished Above target 



North Sea 

Stock 

Species 

Spawning 

biomass in 

relation to 

precautionary 

limits 

capacity 

Fishing 

mortality in 

relation to 

precautionary 

limits 

Fishing 

mortality in 

relation to 

high long term 

yield 

Fishing 

mortality in 

relation to 

agreed 

management 

target 

Sandeel Increased risk Undefined Undefined Undefined 

*No ICES advice is provided for the spring spawning Thames herring so this advice is based 

on that for the North Sea autumn spawners 

Overall summary of GWF baseline – key sensitivities/species of 

concern 

13.4.134 The baseline characterisation has identified that the Outer Thames Estuary 

and GWF are potentially important for a number of commercially important 

species. The GWF overlaps or is in close proximity to a number of finfish 

species spawning grounds including; herring, cod, whiting, sprat, sandeel, 

sole, lemon sole and plaice. The wider Thames estuary also supports 

populations of elasmobranchs including thornback ray which are of national 

significance. A number of migratory fish species such as salmon, sea-trout, 

eel, shad, lamprey and smelt may also pass through the GWF site, although 

only twaite shad were recorded during the site specific surveys. Consultation 

responses have indicated that key sensitive species are considered to be 

herring and sole and in particular disturbance to these species during key 

spawning periods. Available larval data for the Downs herring stock indicate 

that the main spawning ground currently used is within the eastern English 

Channel and that the usage of the Southern Bight spawning grounds with 

which the proposed GWF site overlaps is minimal. Similarly for sole, while 

recent data on the spawning grounds presented by Cefas (2010) indicate that 

the proposed GWF site falls within an area defined as a high intensity 

spawning ground, data on suitable sediments, depth, temperature, salinity 

and maps of habitat suitability support the presence of inshore spawning 

grounds located to the southwest. 

13.5 Assessment of Impacts – Worst Case Definition 

13.5.1 The assessment of potential impacts are based on the worst case scenarios 

for each receptor and establish the maximum potential adverse impact as a 

result. Therefore no impacts of greater adverse significance would arise 

should any other development scenario (as described in Chapter 5) to that 

assessed within this Chapter be taken forward in the final scheme design. 

Full details on the range of options being considered by GWFL are provided 

throughout Chapter 5. For the purpose of the fish and shellfish resource 

assessment, the worst case scenario, taking into consideration these options, 

is detailed in Table 13.9. 



13.5.2 All options considered in Chapter 5, where any range exists (such as pile 

diameter), are considered realistic and therefore, assessing the worst case 

option is considered most practicable and conservative. It is considered that 

if residual impacts on the worst case scenario are acceptable then this will 

apply to all options within the range. 

13.5.3 It is noted that only those design parameters detailed under each specific 

impact have the potential to influence the level of impact experienced by the 

relevant receptor. Therefore, if the design parameter is not discussed then it 

is considered not to have a material bearing on the outcome of the 

assessment. 

13.5.4 The worst case scenarios identified below are also applied to the assessment 

of cumulative impacts. In the event that the worst case scenarios for the 

project in isolation do not result in the worst case for cumulative impacts, this 

is addressed within the cumulative assessment section of the Chapter (see 

Section 13.10). 

. 



Table 13.9 Realistic worst case scenarios for impacts on fish and shellfish. 

Impact Realistic worst case scenario Justification 

Construction 

Disturbance /damage 

through construction 

noise 

Lethal effect and physical injury 

Maximum number of structures (140 

WTGs, three met masts, and four 

ancillary infrastructures) on 7m 

diameter monopiles. The predicted 

noise level associated with a hammer 

blow (1100kJ) for a 7m pile is 254dB 

re 1 µPa @ 1m (see Chapter 5 and 

Technical Appendix 13.B) 

Up to two piles installed at any one 

time (each taking an indicative 4 

hours to install). Based on the 

assumption of one vessel being able 

to install one pile a day (therefore two 

vessels would install a total of two 

piles per day) 70 days of piling will be 

required, taking place intermittently 

over a 39 month period 

(approximately two per week). 

7m piles represent the largest foundation options which require piling and will be 

associated with the loudest noise and therefore considered the worst case for lethal 

effect and physical injury. Criteria used in this assessment comprise 240dB re 1μPa for 

lethality, 220dB re 1μPa for physical injury and the 130dbht metric which represents the 

level at which hearing damage may occur. Lethality may extend to 7m, physical injury 

out to ranges of 130m and for sensitive species such as herring traumatic hearing 

damage may extend out to approximately 1km. Modelled data indicate that during 3m 

piling the levels of noise would not be sufficient to cause lethality although injury could 

still occur out to a maximum of 16m. 

Piling occurring intermittently over 39 months (the longest time period over which piling 

can occur – see Chapter 5) is considered the worst case as it represents the greatest 

potential for lethal effect and auditory injury to occur as a result of the timescale. This 

scenario therefore gives fish that may have left the area as a result of a piling operation 

the opportunity to return and be at risk of physical or lethal injury. 

Monopiles will only be installed out to a depth of 45m below CD. Modelling undertaken 

by Subacoustech (2011) of 3m pin piles (used for space frame foundations) was also 

undertaken to investigate if the installation of smaller piles in deeper parts of the site 

(over 45m where monopiles would not be used) might produce a greater noise impact 

range than 7m monopiles in shallower water (as noise travels further in deeper water). 




Behavioural effects – spawning 

species (herring, sole and cod) 

Maximum number of structures (140 

WTGs, three met masts, and four 

ancillary infrastructures) on 7m 

diameter monopiles. The predicted 

noise level associated with a hammer 

As detailed in Subacoustech (2011), the worse case scenario for noise associated with 

piling is represented by the 7m pile as the noise associated with its installation extends 

the furthest even though it's use in the site is more constrained than space frame 

options. 

Noise from simultaneous piling installation could represent a larger area for lethal effect 

and auditory injury for fish species. The worst case would be that two of the piles 

located furthest from each other within the development area are installed at the same 

time, thus producing the largest area of noise impact. 

Although multiple piling remains a possibility, it is unlikely that more than one foundation 

will be piled at any one time as a result of engineering constraints. In order to ensure a 

thorough assessment, piling of one foundation has been assessed alongside multiple 

piling. 

The options stated will result in the maximum potential for lethality and physical injury. 

Piling is considered to create the greatest potential for noise impacts upon fish species 

during construction. In terms of impacting spawning grounds during key spawning 

periods 7m piles represent the widest behavioural impact ranges (see Table 13.12 

below) with herring for example perceiving levels of underwater noise above 90 dBht out 

to the greatest ranges of approximately 30km for the 7m diameter pile and 20km for the 

3m diameter pile. 

39 months of piling may occur over a 56 month construction window (assuming a Q2 or 




blow (1,100 kJ) for a 7m pile is 254dB 

re 1 µPa @ 1m (see Chapter 5 and 

Technical Appendix 13.B) 

140 piles installed at a rate of two 

piles a day (based on two piling 

vessels onsite) split over two 

consecutive spawning periods with 

this period of 35 days coinciding with 

the key sensitive periods for herring, 

sole and cod spawning. 

Q3 2015 commencement) with piling being restricted to covering no more than two 

spawning periods for the key sensitive species which are considered to be the Downs 

herring and sole. 

Criteria used in this assessment comprise the 75 dBht and 90 dBht levels which represent 

strong and significant behavioural responses by fish species. 

Based on the protracted nature of spawning periods the worst case is therefore 

considered to be the installation of 70 monopiles at a rate of two a day over a period of 

35 days with this period occurring during the peak spawning periods for the relevant 

species. As a worst case, assuming two monopiles are installed every day by two 

separate piling vessels and operations do not run concurrently, a total of eight hours 

piling per day could occur over a 35 day period the spawning season. If piles were 

installed at a rate of one a day, while the duration would be longer, the extent would be 

less. Furthermore, species such as sole and herring have key spawning periods e.g. 

April and November respectively and it is considered that intense piling over this period 

would have the greatest potential for impacts. 

The impact contours (see Section 13.6) associated with the installation of 3m piles do 

not have the same spatial extent and would not impact as much of the spawning 

grounds as the 7m foundation option. 

The options stated will result in the maximum potential for noise disturbance and fish 

species displacement. 




Behavioural effects – general fish 

assemblages 

Maximum number of structures on 

space frame foundations (140 WTGs 

(4 legs), three met masts (4 legs), 

and four ancillary infrastructures (6 

legs). Each space frame foundation 

leg using a maximum of two pin piles. 

The predicted noise level associated 

with a hammer blow (470 kJ) for a 3m 

pin pile used in space frame 

foundations is 239dB re 1 µPa @ 1m 

(see Chapter 5 and Technical 

Appendix 13.B) 

1,192 piles installed over a 39 month 

period (assuming one pile is installed 

at any one time) which equates to 

approximately 1 pile per day 

(assuming construction 7 days per 

week). 

3m piles used for space frame foundations have smaller behavioural impact ranges (see 

Figures 13.25 to 13.27) but represent the foundation option which, as a result of the 

number required, will result in the maximum piling activity occurring over the longest 

period and provides the greatest potential for disturbance and behavioural effects. It is 

considered that if the maximum number of piling operations take place throughout the 

maximum period during which piling might take place this represents the worst case 

scenario due to the continuous noise and subsequent disturbance (see Chapter 5 for 

further details on construction timescales). 

Criteria used in this assessment comprise the 75 dBht and 90 dBht levels which represent 

strong and significant behavioural responses by fish species. 

Modeling carried out by Subacoustech (2011) for 3m piles was carried out at seven 

locations (see Figure 13.21). The worse case predicted noise impact range (in km’s) for 

3m piles (for space frame jacket foundations) for sensitive species such as herring is 

approximately 20km depending on piling location. 

As a worst case, a total of 1,192 3m piles will be required at the GWF if space frame 

foundations are used. This is based on 1,120 3m piles for 140 WTG foundations (based 

on 4 legs and 2 piles per leg), 48 3m piles for ancillary structures (based on 6 legs and 2 

piles per leg) and 24 3m piles for met masts (based on 4 legs and 2 piles per leg). 




Physical disturbance 

of intertidal and 

subtidal habitats 

Structures located across all three 

Development Areas. 

Intertidal 

Trenching across the intertidal area to 

below MHWS where there will be up 

to three rig sites for directional 

drilling, totalling 75m 2 . Vehicular 

disturbance from vehicles associated 

with the preparation of reception pits. 

Subtidal 

Export cable installation via plough 

throughout export cable route (5m x 

190km = 0.95km 2 ) 

Cable installation via plough for inter 

and intra-array cables (300km x 5m = 

1.5km 2 ) 

Anchored construction vessels – up 

to 6 anchors per vessel (up to 4m 2 

per movement)* 

Provides for the maximum amount (spatial extent) of habitat disturbance. 

The worst case scenario is established by defining the maximum amount (spatial extent) 

of habitat disturbance. 

For foundation structures this is represented by the maximum number of structures (140 

WTGs, three met masts and four ancillary structures) which will in tern result in the 

maximum level of disturbance from construction vessel support structures (anchors and 

jack-up legs) 

For export and inter/intra-array cabling the maximum footprint is established through 

assumption maximum extent of cabling using the installation technique with the largest 

footprint). This is represented by the plough, which when considering it’s supporting feet 

has an approximate footprint width of 5m. 

Any other development scenario or installation technique considered within Chapter 5 




Loss of subtidal 

habitat and benthic 

prey resource 

Jack-up vessel - 6 legs of 

approximately 10m 2 per leg. 

Therefore, 60m 2 in total per 

movement with a representative 

maximum number of movements of 

six per foundation and met mast and 

eight for ancillary structures. 

Therefore, the total footprint based on 

a maximum number of 147 structures 

is 0.054km 2 

The total quantifiable construction 

disturbance is therefore is 2.5km 2 

101 * 45m Gravity base structure 

(GBS) foundations with scour 

protection applied to 100% of all 

foundations (160,590m 2 + 174,730m 2 

= 335,320m 2 (0.335km 2 )) 

Three met mast foundations on 45m 

GBS foundations including 100% 

scour protection (4,770m 2 + 5,190m 2 

would result in less of a disturbance footprint. 

The loss of subtidal habitat will result from the placement of built structures (and 

associated scour protection material) on the seabed. The worst case scenario is 

therefore, represented by the largest footprint from the foundation structures (and 

associated scour protection) under consideration. 

The GBS foundations have a larger footprint than any of the foundations under 

consideration. Of the GBS options for the WTGs, there could be up to 101 45m base 

diameter structures or 140 35m base diameter structures. Scour protection for 45m 

base diameter structures is 10m in radius around all structures and 9m around all 




Indirect impacts due 

to loss of fish as a 

= 9,960m 2 (0.01km 2 )) 

Up to four ancillary structures (this 

may comprise a combination of 

offshore substation platforms (OSPs), 

collection platforms and / or 

accommodation platforms) on space 

frame (self-jacking suction can) 

foundations (four leg jackets) 

assuming 100% scour protection = 

18,748m 2 (0.019km 2 )) 

Rock placement for cable protection 

at a total of 9 export cable crossings 

(3,240m 2 ) 

Total area = 0.335 + 0.01 + 0.019 + 

0.003 = 0.37km 2 

As for noise disturbance associated 

with behavioural effects for general 

structures for the 35m base diameter option. Therefore, the total footprint for the 45m 

base diameter option is 335,320m 2 , whilst for the 35m option it is 308,856m 2 . The 101 

45m base diameter option therefore, has the largest overall footprint. 

For the met masts GBS options are considered and therefore, the 45m base diameter 

option presents the worst case. 

For the ancillary structures, only space frame (piled, suction can and self-jacking) and 

monopile foundations are considered. 

The area for a single self-jacking (suction can) space frame foundation (based on up to 

four legs) with 100% scour protection is 4,687m 2 . For the four foundations this equates 

to a total area of 18,748m 2 . 

The area for a single (piled) space frame foundation (based on up to six legs (3m 

diameter) each with up to two (3m diameter) pin piles) is 85m 2 . The piled space frame 

requires 100% scour protection (with an additional 5m radius around each structure) the 

area of scour protection for four space frame structures is therefore 9,388m 2 . 

A 7m monopile has a footprint of 38.5m 2 with a scour protection footprint of 1,700m 2 and 

therefore an overall footprint of 1,739m 2 (total area of 6,956 m 2 for four foundations). 

All other foundation types considered (Chapter 5) would result in a smaller loss of 

habitat. 

3m piles used for space frame foundations have smaller behavioural impact ranges but 

represent the foundation option which, as a result of the number required, will result in 




prey source fish assemblages discussed above. the maximum piling activity occurring over the longest period and provides the greatest 

potential for disturbance, behavioural effects and displacement of fish species. 

Increased 

suspended 

sediments and 

mobilisation of 

contaminants 

101 (45m base diameter) GBS 

foundations for WTG structures, three 

(45m base diameter) GBS 

foundations for met masts, four 7m 

monopile foundations for ancillary 

infrastructure (totalling 500,800m 3 ). 

Seabed preparation for GBS 

comprises mechanical levelling of the 

seabed to a depth of approximately 

2m. 

Turbine installation - two GBS 

foundations installed simultaneously 

over a three day period. 

Cable installation in the marine 

environment by jetting methods to 

install up to three export cables to a 

representative average of 1.5m 

depth, 0.5m width and a total of 190 

export cable kilometres in length. 

The ‘worst case’ scenario is represented by that which could result in the maximum 

volume of arisings (and therefore, maximum volume of material that could brought into 

suspension). 

For the WTG foundations 101 (45m) GBS foundations represent worst case volume 

(484,800m 3 ). Other options result in less volume released: 140 35m GBS foundation 

resulting in 445,340m 3 , 140 7m monopiles 224,000m 3 , 140 space frame foundations 

182,000m 3 , 140 4-legged space frames founded with suction cans 43,960 m 3 and 140 

monopod buckets 70,000m 3 . For the met masts where all foundation types are 

available, again the 45m GBS foundations represent worst case. For the four ancillary 

structures, where GBS are not an option, the worst case is represented by the 7m 

monopile as this structure results in higher levels of spoil material (1,600m 3 per 

foundation). 

Ploughing, trenching and jetting were assessed by ABPmer (2011b), see Chapter 9 and 

Technical Appendix 9.Aiii, with jetting considered to represent the worst case scenario, 

the assumption being that all sediment disturbed would be fluidised and therefore, made 

available for re-suspension. 




Operation 

Disturbance / 

damage through 

Electromagnetic 

Fields (EMF) 

Disturbance / 

damage through 

operational noise 

Inter and intra-array cabling will be a 

total length of 300 cable kilometres 

and have similar burial characteristics 

to the export cables. 

Cabling with 300km of 66kV inter / 

intra-array cabling and up to 190 

cable kilometres of 132kV export 

cable. Representative average 

minimum burial depth for inter / intraarray, 

and export cables will be 0.6m. 

Monopile or GBS foundations for 140 

WTGs 

Aggregation effects Space frame jacket foundations for 

140 WTGs with scour protection and 

rock placement for cable protection at 

a total of 9 export cable crossings 

totalling 3,240m 2 . 

EMF impacts are governed by depth of (cable) burial and not the number of turbines or 

their layout or location within the GWF area. Therefore, the worst case scenario is 

represented by the shallowest burial depth for all cables. Because the burial depth 

achieved varies greatly an average minimum burial depth is applied. 

Provides maximum extent of operational noise based on number of turbines and greater 

radiation efficiency compared to smaller piles associated with jackets. Studies (ÅF- 

Ingemansson, 2007 as cited in Hammar, 2010) have indicated that GBS and monopile 

foundations radiate sound in the same magnitude, with the difference that gravity 

foundations radiate sound in a lower range of frequency than a monopile. 

Provides the maximum potential for change from baseline conditions by providing the 

most complex habitat for fish aggregation. Other structures such as monopiles, GBS or 

suction buckets would provide for the least complex fish habitat structure. 




Indirect impact of 

loss of prey resource 

and habitat from 

changes in current 

regime 

Decommissioning 

104 GBS foundations for WTG 

structures (see Section 9.5), three 

(45m base diameter) GBS 

foundations for met masts, four (7m) 

monopile foundations for ancillary 

infrastructure. Total volume of 

released material from scour of 

446,864m 3 . 

No scour protection measures. 

The indirect impacts on fish species as a result of the loss of benthic prey resource are 

driven by scour events (from changes to current regime) around foundation structures 

and the subsequent release of sediments. 

GBS results in increased scour as a consequence of the larger surface area and hence 

interaction with hydrodynamic flows. 

104 x 45m diameter GBS foundations result in the release in 432,952m 3 of sediment 

while 143 x 35m diameter GBS foundations result in 65,231m 3 of sediment release. 

Individual foundations sediment release rates via scour: 

45m GBS = 4,163m 3 ; 35m GBS = 1,517m 3 ; 7m Monopile = 3,478m 3 ; space frame 

(jacket) = 1,097 m 3 (see Technical Appendix 9.Aiii) 

Therefore, 104 conical 45m diameter GBS foundations (WTGs and met masts) and four 

monopile foundations (ancillary structures, which can only use monopiles or space frame 

foundations) represent the ‘worst case’ scenario 

This scenario results in the release of 446,864m 3 of materials with maximum suspension 

of fine sediment during operation due to scour effects at the turbine structures. 




Loss of habitat Removal of all cabling and build 

structures (based on worst case 

assumptions detailed under 

construction). 

Loss of prey 

resource 

Removal of all cabling and build 

structures (based on worst case 

assumptions detailed under 

construction). 

The precise nature of decommissioning will be established prior to construction and a full 

Decommissioning Plan for the project will be drawn up and agreed with DECC. 

The worst possible potential impacts will be associated by the removal of all structures, 

under which circumstance, impacts will be in line with those specified above for the 

construction phase with the exception of noise impacts, as piling will not take place. 



13.6 Potential Impacts during the Construction Phase 

13.6.1 This section provides an assessment of the impacts from the construction 

phase of the GWF project on the fish and shellfish receptors. Potential 

construction impacts identified during the Scoping process are associated 

with: 

� Disturbance / damage from construction noise; 

� Loss of habitat; 

� Loss of fish as a prey source; and 

� Disturbance from increased suspended sediments and contaminants. 

Impacts due to construction noise 

13.6.2 The main activities relating to the construction of offshore wind farms that 

would be likely to cause noise and vibration disturbance are considered to be 

impact pile driving which could create underwater noise levels significantly 

higher than present background levels. These activities are discussed in 

Chapter 5. 

13.6.3 Pile driving noise during construction is of particular concern as the very high 

sound pressure levels could potentially prevent fish from reaching breeding 

or spawning sites, finding food, and acoustically locating mates (Mueller- 

Blenkle et al., 2010) as well as causing physical injury and mortality or 

disturbing normal behaviour. Consultation responses received from the 

MMO and Cefas (Table 13.1) have indicated concerns related to percussive 

piling noise and its effect on cod, plaice, herring and sole and the potential for 

seasonal piling restrictions relating to the latter two species covering the 

period 1 st November to 30 th May. Following the PER submissions two further 

meetings have been held with Cefas (in July and September 2011) to discuss 

these potential spawning restrictions in context of additional data provided by 

GWFL on the Downs herring spawning grounds have been analysed (see 

Technical Appendix 13.C). 

13.6.4 In UK coastal waters general background levels of sea noise of 

approximately 130 dB re 1 μPa are not uncommon in (Nedwell et al., 2003, 

Nedwell et al., 2007a). Background underwater noise measurements were 

undertaken in the area prior to the installation of GGOWF. These 

measurements indicated that in general the background noise levels range 

from 110 to 150 dB re 1 μPa, equating to 50 dBht for herring (GGOWL, 2005). 

In 2009 broadly similar overall levels were observed although unsurprisingly 

levels were slightly higher as a result of increased shipping traffic due to 

GGOWF construction activity (Gardline, 2010). Increased shipping results in 

an increase in noise at lower frequencies (

13.6.5 The worst case scenario outlined in Table 13.9 is based on piling activities 

occurring over a 39 month period within a 56 month construction window 

(Chapter 5) with piling being restricted to covering no more than two 

spawning periods for the key sensitive species which are considered to be 

the Downs herring and sole. The behavioural disturbance to spawning 

grounds assumes a maximum intensity of pile installation at a rate of two 

concurrent 7m monopiles per day with 140 piles being installed over two 

consecutive spawning seasons (i.e. 70 piles per spawning season). In order 

to assess the worst case for sensitive periods it has been assumed this 35 

day period could occur at any point throughout the 56 month construction 

programme with the maximum impact considered to result from the 

disturbance of two consecutive spawning seasons. The worst case assumes 

a maximum of four hours per monopile installations. 

13.6.6 While the worst case for GWF is based on a four hour piling duration, the 

piling of a 6.3m monopile at GGOWF in a water depth of 31.2m took 

approximately 1.25hrs and required approximately 2,000 hammer blows, 

during which the hammer force reached a maximum of 1,072 kJ (Gardline, 

2010) 

13.6.7 In order to establish the levels of underwater noise from impact piling 

operations for maximum 7m diameter monopiles and 3m pin piles (proposed 

for space frame foundations), site specific modelling was carried out at seven 

representative locations (sites A to G) using a three dimensional underwater 

sound propagation model (INSPIRE v18) (Subacoustech, 2011). The 

INSPIRE model enables the level of noise at various ranges from the piling 

operation to be estimated for varying tidal conditions, water depths and piling 

locations. Although a number of underwater noise propagation models take 

into account the sediment type in the region around the piling operation the 

INSPIRE modelling has indicated that sediment type is not an important 

factor for estimating propagation of impact piling noise (Subacoustech, 

2011). The model is validated against a large existing database of 

measurements of piling noise (Subacoustech, 2011). 

13.6.8 There are two assessment criteria that have been developed for the 

assessment of underwater noise on fish and marine species. The dBht 

(species) metric (Nedwell et al., 2007b) has been developed as a means for 

quantifying the potential for a behavioural impact on a species in the 

underwater environment. As any given sound will be perceived differently by 

different species (since they have differing hearing abilities) the species 

name must be appended when specifying a level. The other assessment 

criteria is based on the M-weighted Sound Exposure Level metric (Southall et 

al., 2007) which has been adopted by the Joint Nature Conservation 

Committee (JNCC) for addressing impacts on marine mammals. To date all 

of the Thames OWF projects have used the dBht metric, including monitoring 

studies during the construction of GGOWF. The monitoring studies for 

GGOWF suggest that the predictions made by the INSPIRE model are 

reasonably accurate and provide a precautionary level of effect. The dBht 

metric method has therefore been used throughout this assessment. 



13.6.9 Based on their physiology, fish species can be separated into different 

categories based on their sensitivity to sound: 

� Hearing generalists are species with either no swim bladder (e.g. 

elasmobranchs), a poorly developed swim bladder or well developed 

swim bladder that is not connected to the ear; and 

� Hearing specialists, which tend to have their swim bladder directly 

connected to the ear increasing their hearing sensitivity (e.g. clupeids 

such as herring). 

13.6.10 Hearing specialists i.e. those fish with specialist structures (e.g. Prootic 

auditory bullae – a gas containing sphere evolved from the bones of the ear 

capsule) have been classified as 'high' sensitivity (e.g. herring), nonspecialists 

with a swimbladder or hearing generalists are 'medium' sensitivity 

(e.g. cod) and non-specialists with no swimbladders are termed 'low' 

sensitivity (e.g. sole and dab) (Nedwell et al., 2004). 

13.6.11 A summary of selected fish species and their sensitivity to sound is provided 

in Table 13.10 below. 

Table 13.10 Example of hearing specialisation of selected fish species 

Common name Swim bladder connection Sensitivity 

Herring Prootic auditory bullae High 

Sprat Prootic auditory bullae High 

European eel None Medium 

Cod None Medium 

Plaice No swim-bladder Low 

Thornback ray No swim-bladder Low 

Dab (sole surrogate) No swim-bladder Low 

13.6.12 The species upon which the dBht analysis has been conducted to inform this 

assessment have been selected based upon the availability of a good quality 

peer reviewed audiogram, their regional relevance in terms of the proximity of 

species spawning sites and concerns raised during consultation. 

13.6.13 Where data for a particular species of commercial or environmental 

significance is not available, a surrogate species may be included in the 

analysis to indicate the likely response of the type of species to underwater 

sound. For example, sole is of commercial significance in UK waters and the 

Thames is known as a spawning ground for this species (Figure 13.10). At 

present, however, there is no audiogram data available for sole. Another 

flatfish, dab, has therefore been included as a surrogate. It should be noted 



that the assumption that similar species have comparable hearing sensitivity 

is not always correct. In this case, the use of dab as a surrogate for sole 

(and also plaice) is considered to be conservative enough to provide an 

acceptable precautionary assessment. 

13.6.14 The fish species considered in this modelling assessment are: 

� Herring, a fish hearing specialist that, based on current peer reviewed 

audiogram data is the most sensitive marine fish to underwater sound; 

� Cod (and other gadoids), a fish hearing generalist that is sensitive to 

underwater sound; 

� Dab, a flatfish species with generalist hearing capability, but that 

based on current peer reviewed audiogram data is the most sensitive 

flatfish to underwater sound – providing a precautionary surrogate for 

sole (and also other flatfish species); and 

� Elasmobranch species, considered to have a low sensitivity to sound 

(Nedwell et al., 2004). 

13.6.15 These species along with a justification of their sensitivities in relation to 

GWF are presented in Table 13.11. 

13.6.16 The MMO raised the comment (Table 13.1) as to whether specific modelling 

on European eel should be undertaken. The assessment has focused on 

those species that are known to be present in the area on a regular basis, 

and particularly those having important spawning grounds in the region (as 

informed by the data used to characterise the existing environment and 

further justified in Table 13.11). Whilst the European eel may pass in close 

proximity to the proposed GWF site during certain life stages (e.g. adult 

migration and returning elvers) its passage would be transient and there are 

no key habitats within the vicinity of GWF which are required as part of the 

eels lifecycle. Furthermore, eels are not thought to have a high sensitivity to 

noise and are considered hearing generalists (Nedwell et al., 2003). The 

modelling is therefore, considered to be commensurate to the sensitivity of 

the species recorded at the site. Qualitative consideration of impacts on the 

European eel is given in the assessment of impacts, detailed below. 

13.6.17 The effects of noise on fish can be divided into the following categories 

(Nedwell et al., 2007a): 

� Lethal injury; 

� Physical injury; 

� Traumatic auditory injury (temporary or permanent loss in hearing 

sensitivity); and 

� Behavioural responses and masking of biologically relevant sound. 



13.6.18 For the purposes of the assessment the lethal, physical and traumatic effects 

are discussed together, followed by consideration of the behavioural 

responses. 



Table 13.11 Sensitivity and importance of the species spawning grounds potentially affected by noise and vibration 

Common 

name 

Herring High 

Value / 

sensitivity 

Justification 

High sensitivity to noise, spawning is restricted by extent 

of available and suitable substrate. 

North Sea herring consist of different discrete spawning 

stocks. GWF overlaps with the Downs herring spawning 

ground and the Thames also contains discrete 

populations of spring spawning (‘Blackwater’ of ‘Thames’) 

herring which do not spawn elsewhere in the North Sea. 

The potential noise impacts could disturb herring during 

spawning; were they subsequently to fail to spawn in large 

numbers, this could affect future recruitment to the herring 

sub-populations. 

Occurrence at the site 

The proposed GWF site just overlaps or lies adjacent to 

an area indicated by Coull et al as being part of the 

wider Downs herring spawning grounds (November to 

January). However, International Herring Larval Survey 

(IHLS) data indicates that in fact the main spawning 

(based on distribution of yolk-sac larvae) is located in 

the Eastern Channel (from Côte d'Opale near 

Dunkerque to Cap d’Antifer near Le Havre on the French 

coast) and that spawning intensity on the Southern Bight 

grounds which overlap with GWF are much less intense; 

long time series data confirm this has been the case 

since the 1970’s (see -Collas et al., 2009 and Pawson, 

1995). The 2000 to 2011 IHLS data presented in 

Technical Appendix 13.C also reflect these trends. 

Two discrete spawning grounds for the ‘Thames’ spring 

spawning herring (mid February to late April) are also 

located to the west of the site near the Blackwater 

Estuary and to the southwest at Herne Bay (Figure 

13.4) both of which are approximately 55km away. 



Common 

name 

Value / 

sensitivity 

Cod Medium 

Sole Medium 

Justification 

Considered a hearing generalist, although are considered 

sensitive to noise and are known to use low level grunting 

sounds during spawning activities. Most energy emitted 

from pile driving activities arises at low frequencies (125 

Hz and 250 Hz, as per Thomsen et al., 2006). GWF is 

located in a low intensity spawning ground and close to 

grounds defined by Coull et al., 1998. Spawning occurs in 

the water column and spawning grounds appear 

widespread and are not restricted to specific areas, 

occurring throughout the North Sea. 

Based on their surrogate dab, sole are considered to have 

a low sensitivity to noise due to the lack of a swimbladder 

although they are known to be sensitive to particle motion 

(Mueller-Blenkle et al., 2010). The GWF site lies within a 

large area indicated as a high intensity sole spawning 

area. The Thames estuary is highlighted as one of the 5 

main spawning grounds in the UK. Important spawning 

areas in the Thames are considered to be the Black Deep 

and Knock which are located more than 20km to the west 

of the site. Data on the occurrence of recently spawned 

eggs supports the presence of inshore spawning grounds 


Cod represented an important component of catches 

during the site specific surveys and also in the 

commercial catches (Chapter 15). Cod are wide spread 

throughout the North Sea. Peak spawning in the 

southern North Sea occurs from the last week of 

January to mid-February. 

Sole represent a commercially important target species 

in the Outer Thames Estuary. By weight and also by 

value (see Chapter 16) sole landings represent an 

important proportion of the landings from GWF site area. 

While sole were not caught in high numbers during the 

GWF surveys they were present in surveys carried out 

for GGOWF and as part of the Outer Thames Estuary 

REC study (MALSF, 2009). The areas of high intensity 

spawning are thought to be associated with the 

shallower inshore waters in the Thames and areas such 

as the Knock and Black Deeps are thought to be of 



Common 

name 

Elasmobranch 

species (e.g. 

thornback ray 

and spurdog) 

Value / 

sensitivity 

Medium 

Justification 


(ICES, 2010a). particular importance. These lie to the east of GWF and 

it is worth noting that the bathymetry shallows between 

these areas and GWF which would result in a higher 

attenuation of construction noise in these areas. 

Elasmobranchs are generally considered to have a low 

sensitivity to sound due to the lack of a swim bladder. 

Due to the depleted status of species such as spurdog 

and the regional importance of species such as thornback 

ray, elasmobranchs have been given an overall sensitivity 

and importance of medium. 

The Thames Estuary is considered to be of national 

importance for thornback ray which were also recorded 

in the GWF surveys. 

While only a single spurdog was recorded during the 

GWF surveys, consultation responses indicate that the 

area of the GWF is thought to be an important pupping 

ground. 



Lethal, physical and traumatic auditory injury effects 

13.6.19 Currently available information suggests that lethality to fish may occur where 

peak to peak levels exceed 240dB referenced to 1 microPascal (dB re. 

1μPa), and physical injury may occur where peak to peak levels exceed 

220dB re 1μPa (Subacoustech, 2011). Nedwell et al., (2007b) has 

suggested that the use of a 130dBht level provides a suitable criterion for 

predicting the onset of traumatic hearing damage, which recognises the 

varying hearing sensitivity of differing species. As discussed in Chapter 5, it 

is predicted that noise levels of up to approximately 254dB re 1 µPa @ 1m 

for a 7m diameter monopile could be expected for the proposed GWF 

project. 

13.6.20 Predictions based on the assumption that, at the onset of pile driving, a high 

blow force would be used indicate that direct impacts such as death, or 

severe injury leading to death, in fish may occur very close to the source of 

peak pressure levels. Work undertaken by Yelverton (1973, 1975) 

highlighted that, for a given pressure wave, the severity of the injury is related 

to the duration of the pressure wave. The Yelverton model also indicated 

that smaller fish were generally more vulnerable than larger ones. While 

specific studies relating to the impacts of piling operations on fish species are 

limited a study performed on behalf of Caltrans (2004) presents the only 

direct evidence of the effect of impact piling on caged fish, and showed that 

there was no damage to steelhead and shiner surfperch at levels of exposure 

up to 182dB re 1μPa (Subacoustech, 2011). 

13.6.21 For the 7m diameter monopile at the proposed GWF site, the modelled data 

indicate that lethality could occur out to ranges up to 7m from the monopile 

and physical injury out to ranges of up to 130m (Subacoustech, 2011). By 

way of comparison the predicted lethal and physical effects ranges for the 

installation of a smaller 6.3m monopile in a water depth of 31.2m at the 

GGOWF were 2m and 40m respectively (Gardline, 2010). The extent of 

traumatic hearing damage effects at GWF varies depending on the species 

considered. The maximum ranges are 0.97km for herring, 0.36km for cod 

and 0.05km for dab (Subacoustech, 2011). The traumatic hearing damage 

range for herring for the installation of a 6.3m diameter monopile at GGOWF 

was estimated at 0.44km (Gardline, 2010). 

13.6.22 Comments received in response to the Section 42 consultation on the GWF 

project raised concerns about the potential impact of piling on fish eggs and 

larvae and in particular those of the Downs herring spawning ground 

population (see Table 13.1) and also species spawning within the region 

such as sole. Unlike adult species fish eggs and larvae are less able to 

actively swim away from sources of underwater noise. 

13.6.23 Further data covering spawning activity over the past ten years has been 

acquired from IMARES. These data are presented in detail in Technical 

Appendix 13.C, and indicate that the majority of the spawning activity within 

this extensive spawning ground takes place in the eastern English Channel 

(160km and 260km to the southwest of the proposed GWF site). As such the 



noise generated from impact piling will not have a spatial overlap with the 

majority of the benthic Downs herring eggs which are located in the East 

English Channel (see Figure 13.22). 

13.6.24 There is large uncertainty about the vulnerability of fish eggs and larvae to 

piling noise and the spatial scale at which mortality or injury will occur 

(Popper & Hastings 2009). Criteria identified by the US Fisheries Hydro 

Working Group (Oestman, 2009 as cited in Bolle et al., 2011) for injury to fish 

from pile driving identified a maximum peak sound pressure levels of 206 dB 

re 1 mPa2 and maximum cumulative SEL of 187 dB re 1 mPa2s for all listed 

fish except those that weigh less than 2 gram. For small fish (

effects. The impact on the Downs herring population and other fish species 

arising from death or physical injury due to piling noise is therefore assessed 

as being of minor adverse significance. 

13.6.29 Aside from mortality and physical injury effects traumatic hearing damage 

may also occur. For this assessment the perceived level of 130dBht has 

been identified as the level of noise at which traumatic hearing damage (i.e. 

permanent hearing impairment as a result of a single transient event) may 

occur. While temporary hearing loss is an injury that is recoverable over a 

period of time, permanent hearing loss results in the death of sensory hair 

cells of the ear and is non-reversible. The conclusion of a review of data on 

auditory injury in fish concluded, in the context of marine fish exposed to 

underwater noise, it is very unlikely that fish would experience auditory injury 

unless constrained in a very high level continuous sound field for prolonged 

periods (Subacoustech, 2011, see Technical Appendix 13.B). Based on 

behavioural reactions to noise it is anticipated that fish species would swim 

away from the piling source and therefore are unlikely to be exposed to these 

high noise levels for any length of time. 

13.6.30 The modelling results for pile driving at high blow forces indicate that 

traumatic hearing damage effects may occur over a range of distances 

depending on the hearing sensitivities of a given species. The data indicate 

that herring could suffer hearing impairment within a range of about 0.97km 

from pile driving operations for the worst case 7m diameter monopile, while 

the ranges for other species are lower. 

13.6.31 The extent of these impacts would be relatively localised (and barely visible 

on Figures 13.22 to 13.24) and restricted to the duration of pile driving 

activities. While the sensitivity of herring is considered to be high, given their 

sensitivity to noise, however the main Downs spawning grounds are located 

in the English Channel approximately 160km to the southwest of the 

proposed GWF site. The number of individuals affected within the 0.97km 

radius by hearing impairments would not be anticipated to have any wider 

population or recruitment impacts for the species. Based on the intermittent 

nature of the piling operations and highly localised nature of the impact, the 

magnitude is considered to be low. Soft start piling would also further reduce 

the magnitude of this impact. The impact on sensitive receptors such as 

herring is assessed as being of minor adverse significance. Based on the 

lower sensitivities and extent ranges for cod and dab (sole surrogate) the 

impacts on these species are assessed as being of negligible significance. 

13.6.32 An analysis was also carried out to determine how close two concurrent 

piling operation would need to be so that the cumulative impact of two 

monopiles being installed at the same time would cause a noise dose greater 

than 90dBht LEP,D for each species and cause auditory injury. These data 

indicate that, for dab, the piles would have to be 50m apart before the 

cumulative dose reaches 90dBht LEP,D. This is clearly unrealistic for wind 

farm construction (with the minimum separation distance being 856m * 

642m), so it can be concluded that impact piling at two locations within GWF 

simultaneously would not increase the risk of auditory injury to dab. For 



herring the critical range where noise dose increases above 90dBht LEP,D is 

calculated at 7km. Therefore, if two monopiles are being installed at 

locations closer than 7km, herring may not be able to swim out of the 

auditory injury zone before receiving a noise dose that is likely to cause 

hearing impairment. As for the assessment of traumatic hearing damage for 

herring above for a single piling event the impact for concurrent piling on 

herring is assessed as being of minor adverse significance. While the 

spatial extent of the impact is anticipated to be larger than that for a single 

piling event the intermittent and temporary nature of the impact would only 

increase to magnitude to low. 

Mitigation and residual impact 

13.6.33 The modelled ranges and discussion presented above are based on the 

assumption of piling at full blow force, which was carried out in order to 

assess the worst case scenario. ‘Soft start’ piling is generally considered 

industry best practice and would be applied at the GWF site; it involves 

gradually ramping up the blow force on the hammer. When a soft start 

procedure is used at the onset of piling, the levels of underwater noise from 

the piling work are lower than during piling at maximum blow force, but above 

the 90dBht strong behavioural avoidance perceived level for many marine 

species at close range (Subacoustech, 2011, see Technical Appendix 

13.B). Any fish species around the piles are, therefore, likely to flee the 

region around the piling operation. For fleeing rates, speeds of 1m.s -1 have 

generally been used during modelling, although in reality herring are 

generally able to swim at much faster rates (Subacoustech, 2011, see 

Technical Appendix 13.B). 

13.6.34 Provided the fish have sufficient time during the soft start procedure to flee to 

a safe distance it is considered unlikely that individuals would experience 

lethal or physical injury, apart from fish larvae and eggs which would be 

unable to swim away form the impact. As a result for adult fish species soft 

start would reduce the magnitude of the impact from low to negligible. While 

based on the impact assessment table (see Table 4.4 in Chapter 4 EIA 

Process) the impact would remain minor negligible it is considered that the 

actual residual impact would be of negligible significance given the 

reduced likelihood of lethal or physical injury. The impact on fish larvae and 

eggs would be very localised and is considered to remain minor adverse. 

13.6.35 Measurements of soft start procedures indicate that the perceived levels of 

noise for herring at the start of the soft start procedure may be reduced by up 

to 18dB for pile driving a 7m monopile at high blow forces (Subacoustech, 

2011). Re-modelling of the data taking into account these lower levels 

indicate that herring could suffer hearing impairment out to a range of up to 

about 220m during installation of a 7m diameter monopile during the early 

stages of the soft start procedure (as compared to 970m at full force) 

(Subacoustech, 2011, see Technical Appendix 13.B). 

13.6.36 Provided the soft start procedure gradually increases the blow force over 

time, fish beyond these ranges should have a sufficient opportunity to flee the 



area out to a safe distance to avoid traumatic hearing impairment. The 

modelling data (Subacoustech, 2011 see Technical Appendix 13.B) 

indicate that the use of the soft start procedure would be likely to provide a 

suitable method of mitigating the possibility of traumatic hearing damage in 

marine fish species (Subacoustech, 2011). Soft starts are standard practice 

in the offshore wind industry and would be applied at the GWF project. 

Combined with the intermittent nature of monopile installation and the fact 

that monopile installation very rarely requires pile driving at full blow force, 

soft start procedures are considered to provide an effective form of mitigation 

for impacts on fish species. With this mitigation in place, the residual impact 

associated with traumatic injury would be considered to be of negligible 

significance. 

Behavioural responses 

13.6.37 Based on a large body of measurements of fish avoidance of noise, a level of 

90dBht(species) has been proposed as the level at which a strong likelihood 

of disturbance to the majority of individuals of a species would be expected 

(Subacoustech, 2011). A lower level of 75dBht(species) has also been used 

to indicate that a significant behavioural impact in approximately 85% of 

individuals is likely to occur, although the response from a species will be 

probabilistic in nature and one individual from a species may react, whereas 

another individual may not. Furthermore, the effect at this level will probably 

be limited by habituation (Subacoustech, 2011). 

13.6.38 The modelling data have indicated that, of the fish species considered, 

herring are likely to perceive levels of underwater noise above 90dBht out to 

the greatest ranges. The ranges to which the noise would be expected to 

remain above 90dBht for this species is 20 to 34km for 7m diameter piling 

operations. By way of comparison, based on the underwater noise 

measurements for the smaller 6.3m diameter monopile installation at 

GGOWF the disturbance range for herring was estimated at 22km (+ 3.3km) 

(Gardline, 2010). 

13.6.39 There may be significant variation in avoidance ranges presented based on 

the location of piling operations and bathymetry. Table 13.12 presents an 

overview of the range of avoidance impact ranges for the three indicator 

species that have been modelled and at the different locations modelled in 

the GWF site. 

Table 13.12 Estimated minimum and maximum impact ranges for a 7m diameter 

monopile at GWF 

90 dBht strong avoidance range (m) Range (km) 

Herring 20 - 34 

Cod 15 - 26 

Dab 6 - 9 



90 dBht strong avoidance range (m) Range (km) 

75 dBht significant avoidance range (m) Range (km) 

Source: adapted from Subacoustech, 2011 

Herring 29 - 62 

Cod 29 - 51 

Dab 16 - 28 

13.6.40 Noise modelling for herring, cod and dab were carried out at various 

locations (sites A to G) within the proposed GWF site in order to demonstrate 

the extent of impact ranges (see Figure 13.18). Modelling plots for two of 

the locations are presented and discussed below. 

13.6.41 The modelling results presented in Figures 13.22 to 13.24 indicate that the 

noise generated by pile driving of a 7m monopile could lead to behavioural 

responses by fish in areas that are indicated by Coull et al.,(1998) as being 

spawning and/or nursery grounds for the species discussed in Section 13.4. 

These areas for herring, cod and sole, taken from Coull et al.,(1998), Cefas 

(2010) and Pawson (1995) have been overlain with the noise contours taken 

from the noise modelling results in order to show the extent of potential 

overlaps with these areas. As indicated for species such as herring the worst 

case is based on concurrent piling at opposite extents of the proposed GWF 

site (See Figure 13.22) which would result in the greatest spatial overlap with 

the spawning grounds as presented by Coull et al., 1998. 

















13.6.42 Several commercially important species have been identified as having 

potential spawning and nursery areas covering the Outer Thames Estuary 

and some of which overlap with the GWF site. 

13.6.43 The proposed GWF site partially overlaps with or lies adjacent to an area 

indicated as forming part of the Downs herring spawning grounds and where 

spawning is indicated as taking place between November and January. 

Herring are demersal spawners and their spawning activities are limited by 

the availability of suitable habitat. The other discrete Thames spring 

spawning herring grounds lie at the mouth of the Blackwater Estuary and in 

Herne Bay and both are approximately 55km to the southwest of GWF; the 

noise modelling indicates these sites would not be impacted by subsea noise 

from the piling operations at GWF (see Figure 13.22). 

13.6.44 Based on the construction window and piling programme, piling activities 

would impact no more than two spawning periods for any species. Whilst it is 

anticipated that much of the offshore construction would, by preference (in 

terms of avoiding inclement winter weather), be completed during the period 

March to November (see Chapter 5) and would therefore fall outside of the 

herring spawning season, as a worst case it remains possible that piling 

activities could occur throughout the year including during the herring 

spawning season. As a worst case, assuming two monopiles are installed 

every day by two separate piling vessels split over two consecutive spawning 

periods a total of 70 piles would be installed over a 35 day period in each 

spawning period, which if operations do not run concurrently would result in a 

total of eight hours piling per day during a key 35 day period over two herring 

spawning seasons. 

13.6.45 Figure 13.22 illustrates the extents to which strong (90dBht) and significant 

(75dBht) behavioural impacts could occur. It also shows that while the piling 

activities at GWF could impact the areas in the Southern Bight indicated by 

the Coull et al.,(1998) maps as possible spawning grounds, the main eastern 

English Channel site where spawning is actually recorded by the IHLS 

surveys would not be disturbed. It is worth noting that while the 75dBht 

contour covers a large area of the area indicated by Coull et al.,(1998) as a 

possible spawning site, this level of underwater noise would only generate a 

behavioural response from some individuals. Furthermore, habituation to 

underwater noise is possible (Subacoustech, 2011) and research shows that 

herring may respond differently to noise depending on the season and their 

physiological state. While not directly related to piling noise disturbance 

Missund (1997) observed higher levels of avoidance to noise from vessels 

when herring were over-wintering than during seasons when they were 

feeding. Furthermore, Skaret et al., (2005), suggest that in relation to vessel 

noise during actual spawning, herring will give priority to reproduction, with 

spawning overruling noise avoidance responses. 

13.6.46 While piling at GWF has the potential to impact on a proportion of the Downs 

herring spawning grounds as identified by Coull et al., (1998), IHLS data and 

the abundance of yolk-sac larvae indicates that the main Downs herring 

spawning grounds are in the East English Channel (see Figure 13.22 and in 



more detail in Technical Appendix 13.C). It is widely acknowledged that 

since the 1970’s these have been the main Downs herring spawning grounds 

(Dickey-Collas et al., 2009, Pawson, 1995, ECA and RPS Energy, 2010, 

Rohlf & Gröger, 2003) and that the herring larvae recorded in the southern 

North Sea originate from spawning grounds in the Eastern Channel (Damme 

pers. Comm., 2011). This is shown by the abundance and distribution of 

yolk-sac larvae for the years 2000 to 2011 (see Technical Appendix 13.C) 

which supports the conclusion that there is currently, and this has been the 

case since at least 2000, no high intensity spawning by the Downs herring 

stock at the Southern Bight spawning grounds and that the proposed piling 

activities at GWF would therefore not significantly impact the main Downs 

herring spawning stock or herring eggs. These trends are also reflected by 

the commercial exploitation of the Downs stock where winter spawning 

aggregations are targeted by fleets in the eastern English Channel at the end 

of the year (ICES, 2009, ICES, 2007a) (see Figure 1.1 in Technical 

Appendix 13.C). 

13.6.47 Based on their high sensitivity to noise and the restricted nature of their 

spawning habitat the Downs spawning herring are considered to have a high 

sensitivity to potential noise impacts. The magnitude of the piling impact on 

the Downs herring is however considered to be negligible. This is based on 

the fact that piling would not impact the main Downs herring spawning 

population which currently utilise the spawning grounds in the East English 

Channel and have done so since the 1970’s. The overall impact is therefore 

considered to be of minor adverse significance. 

13.6.48 It is worth noting that, while the above considers the worst case, the reality is 

likely to be a more intermittent piling programme during the winter months 

where weather windows are restrictive and piles are installed more 

intermittently. 

13.6.49 Concerns were raised during scoping with regard to noise impacts potentially 

masking cod spawning communications and disturbing spawning behaviour 

as they are known to use low level grunting sounds. Peak spawning in the 

southern North Sea is known to occur from January to mid-February. 

13.6.50 Although cod are considered hearing generalists, because they are known to 

use sound during spawning activities, their sensitivity is considered to be 

medium. As discussed for herring above, the worst case assumes that some 

piling would occur during the winter period and, therefore, would overlap with 

spawning activities. Modelling indicates that the impact extents would 

overlap with the spawning grounds indicated by Coull et al.,(1998) (Figure 

13.23). The impact magnitude is considered to be negligible as, as cod 

spawning grounds are distributed widely throughout the North Sea (see 

Figure 13.6) and the piling disturbance would only affect a small proportion 

of the cod spawning grounds in the Southern Bight. Furthermore, the 

duration of the impact would only cover a maximum of two spawning 

seasons. The overall impact is therefore assessed as being of negligible 

adverse significance. This impact assessment would be similar for other 

gadoids species such as whiting, which also have a small proportion of a 



spawning ground overlapping with GWF (see Figure 13.7). Furthermore, 

many marine fish species, including gadoids are generally pelagic broadcast 

spawners and are not limited to specific substrate types as is the case for 

species such as herring. The spawning areas also cover larger areas of the 

North Sea and, as such, localised noise impacts would not be anticipated to 

have a significant effect on the wider stock, given the wider availability of 

spawning habitat. 

13.6.51 The impacts of piling on spawning sole were also raised as a concern during 

consultation (Table 13.1). Sole spawning in the Thames Estuary occurs from 

March to June and based on the construction window (Chapter 5) piling 

works would overlap with this period as piling could occur at any time of year. 

13.6.52 Sole are known to spawn inshore, within the 30m depth contour. Important 

spawning areas in the Thames are considered to be the Black Deep and 

Knock which are located more than 20km to the west of the site. Data on the 

occurrence of recently spawned eggs and also the further data discussed in 

Section 13.4 supports the presence of inshore spawning grounds (ICES, 

2010a) which corresponds to these initially identified by Pawson (1995) with 

spawning in the wider area including in the vicinity of the GWF being at a 

markedly lower intensity. 

13.6.53 The modelling results indicate that the extent of a strong avoidance reaction 

(90 dBht) in the majority of individuals is only anticipated to extend to a 

maximum of 9.5km (mean of 8.7km) from pile driving operations at position 

D. The lower level behavioural impacts at the 75dBht level will potentially 

extend to a maximum of 28km. These figures are a worst case and the 

extents are anticipated to be much lower for the sites closer to the key 

inshore sole spawning areas due to underwater noise attenuating at a faster 

rate in shallower water (e.g. a mean of 8km at site F). The extent of a strong 

avoidance reaction in sole of 9.5km is comparable to the distance of 6.6km 

estimated for sole during the noise measurements for the installation of the 

smaller 6.3m diameter monopile at GGOWF. 

13.6.54 Sole are considered to be relatively insensitive to noise due to the lack of a 

swim bladder although studies have indicated that a range of particle motion 

levels will trigger behavioural responses in sole and cod (Mueller-Blenkle et 

al., 2010). The levels of particle motion generated during pile-driving and the 

distance at which it can be detectable are not known at present (Mueller- 

Blenkle et al., 2010). However, based on the importance of the Thames 

Estuary as a high intensity spawning ground, and their potentially complex 

spawning courtship behaviour their sensitivity to spawning disturbance has 

been assessed as medium. The extent of the noise impacts associated with 

piling operations as obtained from the modelling are presented in Figure 

13.24 where dab has been used as a surrogate for sole. 

13.6.55 The magnitude of piling impacts on spawning sole has been assessed as 

low. This is because, although some lower intensity spawning activity might 

be disturbed around the GWF site during piling operations, there would be no 

substantial overlap with the most important areas of high intensity spawning 



which are considered to take place in the shallower coastal waters within the 

Thames estuary and which are protected from the highest noise levels by the 

shallow Thames bank systems which will lead to rapid noise attenuation as 

can be seen in the results of the noise modelling. Furthermore, the piling 

operations would only impact on two sole spawning seasons. The overall 

impact of the piling activities on sole spawning behaviour is therefore 

assessed as being of minor adverse significance. 

13.6.56 The extent of behavioural impact associated with the piling operations could 

potentially affect the distribution of commercially important fish species within 

the vicinity of the piling operations. The worst case is considered to be the 

use of 3m piles (see Table 13.9) as while the behavioural extents are less 

than that for 7m piles (see Figures 13.22 to 13.27) due to the numbers 

required this foundation option would result in the maximum piling activity 

occurring over the longest period thereby providing the greatest potential for 

disturbance and behavioural effects. 

13.6.57 A number of studies have noted that changes in fish behaviour may arise 

following exposure to relatively low level sounds. Engås and Løkkeborg 

(2002) observed a reduction in the catch of haddock and cod that lasted for 

several days after they had been exposed to seismic airgun emissions and 

Slotte et al., (2004) found broadly similar results for blue whiting and herring. 

Skalski et al., (1992) found that the catch of rockfish reduced by 52% 

following exposure to a single emission of an airgun at 186-191dB re 1 μPa 

(mean peak level). In the case of the GWF piling, the magnitude of this 

impact is considered to be low, based on the short-term and localised nature 

of the displacement that is expected to occur. The sensitivity of fish to such 

short term behavioural displacement is also considered to be low due to the 

wide availability of other suitable foraging and feeding habitat for the 

displaced species and the temporary and reversible nature of the effect. The 

impact is therefore assessed as being of negligible adverse significance. 

13.6.58 The potential impacts of GWF on spurdog pupping grounds were raised 

during consultation (Table 13.1). The information available to date suggests 

that spurdog undertake migrations all round the UK coastline and are 

considered and managed as a single stock. The information available 

suggests that the areas off the west coast of Scotland are one of the most 

important areas for spurdog juveniles. The impact magnitude is considered 

to be low, based on the short-term nature of the impact, which would only 

occur for the duration of the piling operations. While juveniles have been 

recorded from surveys within the vicinity of the GWF site (Figure 13.19) and 

elasmobranch species have a low sensitivity to noise due to lack of a 

swimbladder (see Table 13.10) their overall sensitivity has been assessed as 

medium based on their depleted status (Table 13.11). It is anticipated that 

the impacts of pile driving on spurdog, as well as other elasmobranch 

species, including egg laying rays, would be minimal and localised and, as 

such, the impacts would be considered to be of minor adverse significance. 

13.6.59 The site specific surveys carried out at the proposed GWF site, combined 

with commercial fisheries landings data indicate that shellfish species such 



as crab are present at the site, and in particular, close inshore along the 

cable route. These species may be of value as a commercial species and 

support targeted fisheries (Chapter 15) or as important prey for other marine 

species. 

13.6.60 The first published investigation of invertebrate mortality associated with 

underwater noise was carried out in 1907 and, although studies have been 

carried out since, there is insufficient research on the effects of noise on 

shellfish species. Some studies (e.g. Knight, 1907, Tollefson & Marriage, 

1949, Andriguetto-Filhoa et al., 2005) seem to indicate that shellfish are 

relatively insensitive to noise including from underwater blasting and seismic 

prospecting at close range. The magnitude of the piling impact is considered 

to be low based on the short-term duration of the piling. Based on the 

available information to date, the impact on shellfish species of commercial 

or prey value present at the site is, therefore, anticipated to be of negligible 

adverse significance. 

13.6.61 During consultation concerns were raised in relation to the potential impacts 

of foreshore noise on fish (Table 13.1). Construction related activity using 

construction plant is anticipated to occur on the foreshore in relation to the 

cable landfall (Chapter 5). The works associated with the cable landfall 

include the use of directional drilling to connect the cables from the high 

water mark to the onshore transition bay (see Chapter 5). Construction 

activities on the foreshore would create air borne noise. Due to the acoustic 

impedance effects of the amount of acoustic energy transferred from one 

substance to another (for air and water this difference is large) airborne noise 

would not contribute significantly to levels of underwater sound. The main 

pathway for construction plant or drilling activities impacting fish populations 

would be through low frequency vibration impacts. These vibration impacts 

are only anticipated to be localised due to the dampening effects of the sand 

/ soil substrate. Any construction related activities would be associated with 

the installation of up to three export cables and would therefore be of shortterm 

duration. The magnitude is therefore considered to be negligible. The 

sensitivity of fish species to the low levels of noise or vibration during any 

onshore works are considered to be low. Overall the impact significance is 

therefore assessed as negligible adverse. 


13.6.62 Consultation responses received from the MMO indicated the potential for a 

piling restriction from 1 st November to 31 st May to cover the sensitive 

spawning periods for the Downs herring stocks and sole (Table 13.1). The 

data presented on piling noise effects and the distribution of the Downs 

herring spawning grounds discussed above show that there is no risk of likely 

significant effect on the main Downs herring spawning population in the 

English Channel. Similarly for sole, the data for the Thames Estuary on sole 

spawning habitat suitability, association with reduced salinity, shallower 

inshore water and increase temperature reflect the sole spawning areas 

identified by Pawson (1995). Piling noise during construction is not 

anticipated to cause a significant behavioural overlap with these grounds. 



This combined with their relative insensitivity to underwater noise suggests 

that there is no risk of likely significant effect on the main spawning 

populations. As such it is felt that for the Downs herring and also sole, given 

the lack of significant risk, such mitigation is not justified. 

13.6.63 Further discussions are ongoing with the regulators to establish the actions 

that are required in order to bring any necessary restrictions in line with the 

anticipated impacts associated with the proposed GWF development. 

13.6.64 As discussed previously mitigation in the form of soft start piling will be 

incorporated into construction procedures. However, while such measures 

would reduce the impacts associated with lethal and physical injury, once 

piling reaches full blow force the behavioural impact ranges would remain 

unchanged compared to the pre soft start predictions. Despite the lack of 

significant impact predicted on herring or sole spawning grounds, further 

precautionary mitigation is applied through the commitment to restrict piling 

activity to a maximum overlap of two spawning seasons for each of the two 

(herring and sole) species over the 56 month construction window. This 

effectively imposes a piling restriction for two of the four potential seasons 

that occur within such a window (assuming a Q2 or Q3 2015 

commencement). 

13.6.65 Given the above it is considered that the residual impact on key receptors 

such as the Downs herring and sole spawning grounds and elasmobranchs 

would remain minor adverse. The impact to other receptors discussed is 

anticipated to remain of negligible adverse significance. 

13.6.66 Physical disturbance of intertidal and subtidal habitats 

13.6.67 The physical disturbances to the intertidal and subtidal habitats are 

discussed in Chapter 12, Section 12.6. It is anticipated that there will be 

some degree of disturbance to benthic communities as a result of the cable 

and WTG installation. It is anticipated that some scavenging fish, crustacean 

and invertebrate species may be attracted to the recently disturbed seabed to 

feed on the recently exposed and damaged benthic animals. These 

disturbance impacts are however anticipated to be temporary and reversible 

and are not anticipated to result in any long term changes in fish or shellfish 

communities. The magnitude of the impact is considered to be negligible 

based on the limited extent of the disturbance and short term duration. While 

species may be attracted to such disturbance events their sensitivity is 

considered to be low based on the localised effects and limited extent of any 

behavioural changes. The overall impact is therefore assessed as being of 

negligible significance. 

Indirect impacts due to loss of fish as a prey source 

13.6.68 Fish species represent important prey for other species including birds, 

marine mammals and other fish. Concerns have been raised (by the Royal 

Society for the Protection of Birds see Table 13.1) regarding the impact of 

GWF on prey and food availability for other species. The impacts of GWF on 

benthic invertebrates, a fish prey resource, is discussed in detail in Chapter 



12 with the conclusion that there would be no significant impacts or changes 

in community structure. Similarly, the relationship between certain bird 

species, prey availability and the association of bird distributions with 

commercial fishing activities are discussed in Chapter 11 Offshore 

Ornithology. Fish, including sandeel and juvenile life stages of species such 

as herring, and sprat also form an important prey source for other larger fish 

species. The main construction related impacts on fish species are 

discussed in the relevant sections above and below. The main activities with 

the potential to have a significant impact on fish are associated with the 

installation of 7m diameter monopiles via pile driving. 

13.6.69 As discussed above, the potential impacts to fish species include mortality at 

close range. However, the localised nature of these impacts would not be 

anticipated to have any significant wider ranging effects. Furthermore, it 

could be possible to reduce the extent of mortality associated with pile driving 

operations through the use of mitigation measures such as soft starts. While 

it is anticipated that significant mortality impacts can be reduced through the 

use of appropriate mitigation, the underwater noise generated from impact 

piling operations could result in hearing sensitive fish such as herring and 

sprat temporarily moving away from the construction area for the duration of 

piling operations. Piling operations are intermittent, with pile driving rarely 

occurring for more than four hours. Any displacement of prey species would 

therefore only occur for a short duration, a response that may be mirrored by 

their predators. It is anticipated that the overall effects on fish as a result in 

the loss of other fish as prey resources, would be negligible. 

13.6.70 The implications of the loss of fish prey resource in relation to marine 

mammals and birds is discussed in Chapter 14 and Chapter 11 respectively. 

Impacts due to increased suspended sediment concentrations 

13.6.71 Increased suspended sediment load has the potential to impact on fish and 

crustacean species as well as affecting larvae and egg stages. The impact 

of increased suspended sediment concentrations (SSC) and volumes likely 

to be produced are assessed in Chapter 9 and Technical Appendix 9.Aiii. 

The impacts on water quality are assessed in Chapter 10. These 

assessments concluded that the levels of SSC associated with foundation 

installation will be elevated, above natural background levels, by no more 

than 1.4 mg/l (fine sands). The export cable installation could potentially 

elevate SSC temporarily in the immediate vicinity of the cable installation 

activity, however these are anticipated to remain below 0.5 mg/l. The 

potential increases in SSC for both cable and foundation installation are likely 

to be of negligible significance in terms of change to existing conditions (see 

Chapter 9). 

13.6.72 Key concerns raised during consultation on GWF relate to the effects of 

suspended sediment impacts on spurdog pupping grounds and other egg 

laying elasmobranch species (Table 13.1). Given their large size at birth (26- 

28cm) it is anticipated that, similarly to other mobile fish species, spurdog 

would be able to detect the elevated levels of suspended sediments and 



move away from the affected area. As such spurdog sensitivity to such 

impacts is considered to be low. Research carried out on herring and cod 

(Westerberg et al., 1996) indicates that these species have definite 

suspended sediment thresholds (approx 3mg/l) and are, therefore, likely to 

avoid the areas closest to the foundation installation. 

13.6.73 Larval species and eggs, especially for herring, could also be affected by 

increased levels of suspended sediment. Research on the embryonic 

development of herring eggs (Kiorboe et al., 1981) at levels similar to those 

anticipated to be released as a result of the cable installation (5 – 300mg/l) 

found no effects after prolonged exposure (10 days). The sensitivity of larvae 

and eggs to the levels of suspended sediments anticipated to occur during 

the construction activities are therefore considered to be low. Furthermore, 

the levels of SSC predicted as a result of the construction activities are 

considerably lower than the levels larvae and eggs would be exposed to 

naturally as a result of regional maximum SSC concentrations especially 

winter concentration which may range from 64 to >250 mg/l for shallower 

inshore waters (see Chapters 9 and 10). 

13.6.74 Skate and ray species along with other oviparous elasmobranch species are 

known to lay egg cases. Suspended sediment can cause mortality of 

embryos through blocking of the respiratory fissures or horns (Richards et al., 

1963 as cited in Leonard et al., 1999). There is currently little known about 

the habitat requirement for skate and ray egg laying and it is unclear whether 

they have discrete egg laying beds. The 2m beam trawl surveys carried out 

for GWF site characterisation (as detailed in Section 13.3) did not identify 

any high densities of egg cases in the vicinity of GWF. While it is possible 

that egg cases could be affected by the localised sedimentation, it is not 

anticipated significantly large numbers would be impacted. The overall 

sensitivity of the receptor is, therefore, considered to be low. 

13.6.75 The magnitude of the impact is assessed as low, based on the localised 

intermittent nature of the impact. In view of the above, the effects of the 

impacts associated with the turbine and cable installation on fish, larval and 

egg receptors would be considered to be of negligible significance. 

Indirect impacts through re-mobilisation of contaminated sediments 

13.6.76 The re-suspension of seabed sediments could also lead to the release of 

contaminants present within them, which may have direct and indirect 

impacts on fish and shellfish resources within proximity of the GWF site. The 

impacts of contaminants on water quality are discussed in Chapter 10, 

Section 10.6 and in relation to benthic ecology in Chapter 12, Section 12.6. 

The data presented in Chapter 10, Section 10.4 shows that the levels of 

contaminants in the sediments are below guideline and action levels. 

Sampling at GWF was seen to establish similar contaminant levels within its 

sediments to those present at GGOWF with only elevated levels of arsenic 

detected. Arsenic is well known to occur at elevated levels in the region of 

the Outer Thames Estuary and has been attributed to both historic and 

geological inputs (see Chapter 10, Section 10.4). The fish fauna of the 



Outer Thames Estuary inhabit an area of very mobile sediments, and must, 

therefore, be frequently exposed to generally raised levels of arsenic in the 

sediments and their sensitivity to the levels which are anticipated to occur are 

considered to be low. Based on the localised and intermittent nature of any 

sediment re-suspension the magnitude is considered to be low. 

13.6.77 It is anticipated that the impact of re-mobilised contaminants on the fish and 

shellfish resources would be of negligible significance. 

Impacts due to loss of habitat and benthic prey resource 

13.6.78 During the construction phase there will be permanent loss of habitat for fish 

and crustacean species in the direct footprint of the foundations. The 

potential habitat loss is only likely to have significant effects if the habitat is 

not widely distributed elsewhere or if the habitat is an essential piece of 

spawning ground for demersal spawners such as herring for example. 

13.6.79 The installation of WTG, foundation structures and supporting infrastructure 

will result in long term loss of seabed and associated habitats and fauna 

within the footprint of the structures for the life of the scheme (circa 25 years). 

13.6.80 Using the worst case build scenario detailed in Table 12.3 (Chapter 12) the 

maximum loss of seabed is anticipated to be 0.37km 2 (from WTG footprint, 

scour protection, ancillary structures and cable protection materials at cable 

crossings (see Table 12.3 (Chapter 12) for detail). The total area affected 

will constitute 0.17% of the total consent area (222km 2 ). The majority of 

seabed lost will be as a result of the WTG foundations and associated scour 

protection. 

13.6.81 The loss of benthic communities is assessed in detail in Chapter 12 with the 

main communities affected being the polychaete-rich deep Venus community 

which is widespread at a regional level. 

13.6.82 While shellfish species have been recorded at GWF, the area does not 

represent part of any significant shellfish beds in the Outer Thames Estuary. 

Similarly, only a small proportion of Area B overlaps with areas indicated by 

Coull et al., as forming part of the Downs herring spawning grounds. The 

drop-down and benthic grab surveys concluded that the majority of sediment 

throughout the GWF survey area were poorly sorted and did not offer ideal 

conditions for herring to spawn on (CMACS, 2010, see Technical Appendix 

12.A). There would therefore be no impact due to the loss of herring 

spawning ground. Furthermore, since the 1970’s the main Downs herring 

spawning grounds used have been those in the eastern Channel. 

13.6.83 Monitoring studies at other wind farm sites such as Kentish Flats have 

generally indicated that there has not been a significant effect on the fish 

species present, suggesting that the presence of the wind farm, including the 

direct loss of habitat, had not had a significant effect (Cefas, 2010b). This 

suggests that fish species are relatively insensitive to such small changes or 

loss of seabed habitat and their sensitivity to these impacts is therefore 

considered to be low. Given the localised nature of the habitat loss the 



magnitude is considered to be low. The impacts of habitat loss on fish 

species would be of negligible significance. 

13.6.84 It is noted that some consultees have raised the question over the potential 

for artificial reefs to be included in the design to help mitigate impacts on fish 

resource. No additional material or structures to that accounted for within the 

project envelope (see Chapter 5) will be provided. It is noted that the 

addition of any new material would further impact on the existing environment 

and not necessarily have a positive impact. The effect of the new structures 

and associated material that would be introduced into the environment as a 

result of the construction of the proposed wind farm is discussed below under 

operational impacts. 

13.7 Potential Impacts during the Operational Phase 

13.7.1 This section provides an assessment of the impacts from the operation 

phase of the GWF project on the fish and shellfish receptors. Aspects 

associated with the operation phase (as identified during the Scoping 

process and subsequent consultation) include: 

� Disturbance due to operational noise; 

� Disturbance from EMF; 

� Aggregation effects; and 

� Loss of prey resource and habitat from changes in current regime. 

Disturbance through noise and vibration 

13.7.2 When a wind farm is operational, the main source of underwater noise will be 

mechanically generated vibration from the WTGs, transmitted into the sea 

through the tower structure and foundation (Nedwell et al., 2003). The 

underwater noise generated during the operational phase of a wind farm is 

much lower than the levels created during construction piling. However, 

unlike the temporary pile driving noise, operational noise will span the lifetime 

of the wind farm (Nedwell et al., 2007a). 

13.7.3 Measurements of operational noise at a series of wind farm sites indicated 

that the level of noise during the operational phase was found to be very low 

(Nedwell et al., 2007a). The study calculated the operational noise levels 

that would be encountered by various species using dBht units. When the 

results were averaged across all of the fish species considered, the noise 

levels within the wind farms were found to be just over 2dB higher than 

background noise levels in the immediate environs (Nedwell et al., 2007a). 

The variations in level are well within the spatial and temporal variations that 

are typically encountered in background noise, and hence it was concluded 

that, while there might be a small net contribution to noise in the immediate 

vicinity of the wind farm, this is no more than is routinely encountered by 

marine animals during their normal activity (Nedwell et al., 2007a). 

Furthermore, dive surveys of operational wind farms have indicated that the 



total fish abundances in the vicinity of turbines are often higher than 

surrounding areas (Wilhelmsson et al., 2006). 

13.7.4 Studies of operational wind farm noise in at Lillgrund in Sweden indicate that 

species like eel and salmon which have a poor sensitivity to sound pressure 

will only detect operational wind farm noise (during maximum production, 

wind speeds of 14 to12 m/s) at a distance less than 1km (Andersson, 2011). 

Fish with higher sensitivity of sound pressure, e.g. herring and cod, might 

detect the wind farm at a distance greater than 16km although at this 

distance, the ambient noise will mask out the wind farm noise (Andersson, 

2011). These results are in line with other estimations such as the figures 

calculated by Thomsen et al., (2006) for species such as eel although the 

zone of audibility for herring and cod was smaller and in the region of 4-5km 

from the source. Fish lacking a swim bladder (e.g. gobies and flatfish) will 

only sense the measured particle acceleration at distance of about 10m from 

the foundation and at greater distances most species are limited by either 

their hearing threshold or the ambient sound masking the wind farm noise 

(Andersson, 2011). 

13.7.5 The sensitivity of fish species to such small levels of noise are considered to 

be low. The magnitude of the impact is also considered to be low given the 

localised extent of the impact. As such, the impact to fish species from 

underwater noise and vibration during operation would be of negligible 

significance. 

Disturbance through presence of electromagnetic field (EMF) 

13.7.6 EMF will be generated by the GWF export, inter and intra-array cables. The 

worst case scenario set out in Table 13.9 establishes that there will be up to 

300km of 66kV AC for the inter and intra array cables, and up to three AC 

132kV export cables with a combined length of 190km, all buried to a 

representative average minimum depth of 0.6m. 

13.7.7 It is important to note that 0.6m is not a ‘target’ depth, but a worst case 

recognition that it may not be possible to bury the cable to a desired depth 

(around 1.5m) across the whole cable extents. Such instances may arise 

where ground conditions to not permit a target depth burial depth to be 

achieved or when the cable rises to join with offshore substation platforms 

(OSP), or when crossing other cables) the cables may have to be installed on 

the surface and covered with concrete mattresses. For the purpose of this 

ES the indicative cable arrangements are presented in Chapter 5. 

13.7.8 The EMF and their constituent fields; electric (E field), magnetic (B field) and 

associated induced electric fields (iE), produced by the inter-array and export 

cables could affect the behaviours of certain electrosensitive species. 

13.7.9 A simplified overview of how induced electrical fields are produced by AC 

power cables is presented in Plot 13.10. 



Plot 13.10 Simplified overview of how induced electrical fields are produced by AC 

power cables 

Source: Gill et al., (2009) 

13.7.10 The electrolytic properties of sea water mean that a small current is induced 

in the water, with this being in the order of 0.1 mA/m² (CMACS, 2003) (for the 

example of one cable buried 1m in the seabed) and which induces an E-field 

of around 25 μV/m (conductivity of 4 Siemens/m). An alternative example 

given in the COWRIE report (CMACS, 2003) reports an E-field of 91μV/m for 

a 132kV XLPE three-phase submarine cable designed by Pirelli with an AC 

current of 350 amps buried at a depth of 1m. Table 13.13 indicates that in 

both these cases it is likely that the EMF from these cables would be 

detected by electro-sensitive elasmobranch species. 

Table 13.13 Elasmobranch sensitivity to electrical fields 

Sensitivity E-Field range 

Elasmobranch sensitivity: 0.5 – 1000 µV/m 

Potential range of attraction: 0.5 – 100 µV/m 

Potential range of repulsion: > 100 µV/m 

Source: CMACS, 2003 

13.7.11 All of the cables will, where ground conditions allow, be buried to a nominal 

target depth of 1.5m with the aim to bury all cables at least 0.6m (except for 

transitional lengths to surface structures). Based on the information 

discussed above and presented in Table 13.13 where cable burial depths are 

less than 1.5m it is expected that the E-fields are likely to be of a level 

expected to attract elasmobranchs. 



13.7.12 While most fish species are able to sense EMFs, elasmobranchs and 

migratory species are considered the key sensitive receptors to any effects 

that may manifest. The majority of the elasmobranch species occurring in 

the UK are benthic species inhabiting shallow sandy areas. Concern over 

potential interactions between wind farm cables and elasmobranchs has 

been raised (Gill, 2005; Gill et al., 2005; Sutherland et al., 2008). 

13.7.13 Migratory species, such as salmonids or anguillid eels, are also known to be 

sensitive to EMF, especially at specific stages of their life cycle, principally 

during migration. Some fish species that are regarded as EMF sensitive do 

not possess specialised receptors, but apparently are able to detect induced 

voltage gradients associated with water movement or geomagnetic 

emissions (Gill & Bartlett, 2010) (see Table 13.14). The physiology of these 

sensory mechanisms for the detection of EMF is poorly understood, and is 

likely to vary on a species by species basis (Pals et al., 1982 as cited in Gill & 

Bartlett, 2010). It is likely that the species listed in Table 13.14 will respond 

to EMF that are associated with peak tidal movements, which can create 

fields in the range of 8-25 μv m-1 (Barber & Longuet-Higgins, 1948; Pals et 

al., 1982 as cited in Gill & Bartlett, 2010). 

13.7.14 The effects of B and iE fields on fish species depends on their physiology. 

Many species are sensitive to bioelectric fields or use magnetic fields to aid 

migration. 

13.7.15 Migratory species, which are known to undertake long distance migrations, 

such as the European eel and some salmonids, are known to have magnetic 

material in various part of their body which is of the right properties to 

facilitate magnetic detection. Telemetry studies of migratory patterns of 

European eel in the vicinity of a WTG in the Southern Baltic by Westerberg 

(as cited in Öhman et al., 2007) did not show any altered migratory 

behaviour, at least not 500m beyond the WTG. Catch statistics at eel pound 

nets in the area did, however, indicate an effect of whether the WTG was on 

or off. If this should be attributed to the effect of acoustic or electromagnetic 

disturbances was unclear. An unpublished study on migrating silver eels 

across a 130kV AC cable in Sweden by Westerberg and Lagenfelt (as cited 

in Öhman et al., 2007) found swimming speeds to be significantly lower in 

proximity to the cable with, on average, a 30 minute delay in migration. 

13.7.16 Potential prey species such as brown shrimp Crangon crangon have also 

been recorded as being attracted to the B fields of the magnitude expected 

around wind farms (ICES 2003). 

13.7.17 Elasmobranchs have been shown to respond equally to natural and artificial 

E field upon first encounter, raising concerns that predators such as 

elasmobranchs may waste time and energy “hunting” E fields associated with 

cabling whilst searching for bioelectric fields associated with their prey 

(Kimber, 2008). Such effects could ultimately reduce reproductive success 

and have wider population effects (Kimber, 2008). Elasmobranchs are 

known to respond to magnetic fields (25-100 μTesla; Meyer et al., 2004) and 

are thought to use the Earth’s magnetic field (approximately 50 μTesla) for 



migration. They also respond behaviourally to electric fields emitted by prey 

species and conspecifics. Further studies of ray egg cases have also 

demonstrated that embryonic thornback rays cease body movement that 

facilitates critical ventilatory movement of water upon sensing artificial E 

fields. This suggested the rays were employing detection minimisation 

behaviour as the E fields were similar to those of predatory animals (small, 

adult elasmobranchs and teleosts (Ball, 2007). 

Table 13.14 Evidence based list of electromagnetic sensitive teleost fish species and 

their conservation status (according to the IUCN Red list) in UK coastal 

waters. Superscript numbers show reference sources. E field = Electric 

Field; B field = Magnetic field 

Species 

European eel 

Anguilla anguilla 

Atlantic salmon 

Salmo salar 

Sea trout 

Salmo trutta 

European plaice 

Pleuronectes platessa 

Yellowfin tuna 

Thunnus albacares 

European river lamprey 

Lampetra fluviatilis 

Sea lamprey 

Petromyzon marinus 

Conservation 

status 

Critically 

Endangered 

Least 

Concern 

Least 

Concern 

Frequency 

in UK 

Waters 

Evidence of 

response to 

E fields 

Evidence of 

response to 

B fields 

Common ✓1,2x ✓3,4 

Common ✓5,6x ✓5,6 

Occasional ✓7 

Vulnerable Common ✓8, ✓8 

Least 

Concern 

Near 

Threatened 

Least 

Concern 

Occasional ✓9-12 

Common ✓13,14 

Occasional ✓5-17 

1 Berge (1979); 2 Vriens & Bretschneider (1979); 3 Enger et al. (1976); 4 Westerberg 

(1999); 5 Moore et al. (1990); 6 Rommel & McCleave (1973); 7 Formicki et al. (2004) – 

juvenile fish; 8 Metcalfe et al. (1993); 9 Kobayashi & Kirschvink (1995); 10 Walker et al. 

(1984); 11 Walker (1984); 12 Yano et al. (1997); 13 Gill et al. (2005); 14 Akeov & Muraveiko 

(1984); 14 Bodznick & Northcutt (1981); 15 Bodznick & Preston (1983); 16 Bowen et al. 

(2003); 17 Chung-Davidson et al. (2004) 

Source: Gill & Bartlett, 2010 

13.7.18 EMF modelling of cables at a series of wind farms (Gill et al., 2005) also 

demonstrated that there was a linear relationship between current load and 

resultant B and iE fields, with both fields directly proportional to current load 



such that halving the current halved the resultant fields i.e. when the wind 

farm is operating below maximum capacity (i.e. at average wind speeds) the 

resultant B and iE fields will be less. Electromagnetic fields are proportional 

to current and, as a result, high cable operating voltages will reduce the 

potential impact. Increasing the voltage from 33kV to 132kV consequently 

reduces the induced E-fields by a factor of four (CMACS, 2003). 

13.7.19 The conclusions from the most recent COWRIE mesocosm studies into EMF 

effects provided evidence of responses to the presence of EMF of the type 

and intensity associated with subsea cables. However, the responses 

observed were not predictable and appeared to be species specific and 

perhaps individual specific and, as such, there was no evidence to suggest 

any positive or negative effect on elasmobranchs of the EMF encountered 

(Gill et al., 2009). 

13.7.20 Based on the information available, it is clear that fish species may respond 

to EMF. However, the magnitude and extent of the B and iE fields are 

anticipated be localised. Furthermore, while the duration of the effect would 

occur for the lifetime of the project, the intensity of EMF varies depending on 

the operating capacity of the wind farm. The overall magnitude is therefore 

considered to be low. Sensitive species would, therefore, not always be 

exposed to the highest levels of EMF as these may fluctuate depending on 

wind conditions. However, given the sensitivity of elasmobranchs and 

migratory species to detecting EMF and the uncertainty associated with the 

behavioural response to EMF the precautionary assessment of receptor 

sensitivity is high. 

13.7.21 Given the low magnitude of the effect combined with the high sensitivity of 

the receptor the overall impact of EMF on sensitive species would be of 

minor adverse significance. 


13.7.22 In order to reduce the likelihood for cable burial not being sufficient a 

dedicated cable burial protection plan will be developed once the final route 

has been established and site (geophysical and geotechnical) surveys 

undertaken (this will not prevent suboptimal burial but can aid in establishing 

further options if a scenario of insufficient burial presents itself). This cable 

burial protection plan will be informed by a Burial Protection Index (BPI), 

which will assess the risks (physical, human and environmental) along the 

route and set out target burial depths in accordance with the associated risks. 

Whilst this mitigation will serve to lower the potential for extensive areas of 

shallow buried cable, it will not remove the potential for some limited extents 

to remain below desired depths (1.5m in line with EN-3 recommendations). 

Consequently, magnitude remains low and the impact of minor adverse 

significance. 

Aggregation effects 

13.7.23 The concrete and steel wind farm structures are likely to become colonised 

by a range of benthic invertebrate species (see Chapter 12) and this 



increase in the overall diversity and productivity of the local seabed 

communities as well as providing shelter against strong currents and 

predators which in turn could lead to an aggregation of fish species. This will 

increase the number of mobile fauna concentration, such as fish, near the 

artificial reefs (Hammar et al., 2010). 

13.7.24 In a perspective of preservation of the natural existing environment, fouling 

and reef-effects may be considered as negative environmental impacts in 

areas without the presence of, or proximity to natural hard bottom (because 

of the risk of introduction of alien species which can change the ecological 

conditions) (Hammar et al., 2010). The worst case is considered to be the 

scenario which would result in the maximum potential for change. 

13.7.25 Regarding the reef-effect, the complex structure of a jacket space frame 

foundation is expected to generate habitats for more species (e.g. fish) than 

a more homogenous model of foundation like monopile (Hammar et al., 

2010). Space frame WTGS are therefore considered as the worst case. 

Abundant reef-effects have been observed on oil platforms around the world 

and the structures of these are similar to jacket foundations. Furthermore, 

more deep living species might exploit the food availability and the various 

habitats of the artificial reef of jacket foundation since they are planned to be 

placed at greater depths (Hammar et al., 2010). 

13.7.26 Investigations of fish abundance at wind farms using underwater visual 

census techniques, carried out by Wilhelmsson et al., (2006) found that while 

total fish abundance was greater next to foundations for some species there 

were no increases in species richness. Results from this study suggest that 

offshore wind farms may function as combined artificial reefs and fish 

aggregation devices for small demersal fish. 

13.7.27 As discussed in Chapter 12, in relation to changes in benthos there is clearly 

potential to increase habitat complexity and improve productivity and studies 

such as those by Wilhelmsson et al., (2006) have shown changes in fish 

assemblages. However, given the localised nature of these changes and 

given the distances between the GWF structures, these potential aggregating 

effects are not anticipated to result in notable wide scale changes in fish 

communities or abundances. Given that fish and crustacean species will be 

protected from activities such as fishing as a result of safety zones around 

WTGs (which will be applied for post consent) the overall impact is 

considered to be of negligible beneficial significance. 

Indirect impact of loss of prey resource and habitat from changes in 

current regime 

13.7.28 The effects of the operational phase of the proposed GWF on the 

hydrodynamic and consequently sediment regime are assessed in Chapter 9 

and in more detail in Technical Appendix 9.Aiii. The subsequent indirect 

impacts on subtidal ecology are assessed in Chapter 12 which are limited to 

sediment scour within close proximity to a small percentage of the 

foundations. This scouring could have a direct and localised impact on the 



fauna within the footprint of the scour which may have indirect implication on 

fish and crustacean as a result of loss of benthic prey resource. 

13.7.29 The assessment on subtidal ecology concluded that the potential effects 

upon suspended sediment concentrations and benthic ecology would be 

minimal given the small area affected and anticipated that as a worst case 

the impact would be of negligible. Based on this assessment it is also 

anticipated that the indirect impacts on fish as a result of this loss of prey 

resource would be of negligible adverse significance. 

13.8 Potential Impacts during Decommissioning 

13.8.1 As stated in Table 13.9, the final decommissioning proposals will be 

established prior to construction in agreement with the MMO and relevant 

SNCAs and stakeholders. Options at the end of the operational lifetime of 

GWF include removal of all infrastructure, leaving cables in situ but removal 

of all foundation structures and scour protection (or repowering which would 

be considered under a separate consenting process). As a precautionary 

worst case scenario for the purposes of this assessment it is assumed that all 

GWF infrastructure will be removed as this would lead to the highest number 

of boat movements, duration of activity, noise and disturbance to the seabed. 

Loss of habitat 

13.8.2 It has been assumed that decommissioning will include the removal of all 

offshore structures, GBS foundations will be fully removed and piled 

foundations will be cut off at or just below the seabed. The removal of this 

infrastructure will necessitate the use of a heavy lift vessel. It is expected 

that burial depth will be an important factor in helping to determine the 

appropriate course of action for removal of cables and will therefore be 

closely monitored throughout the project life-cycle. A typical cable removal 

programme will include the following 

� Identify the location where cable removal is required; 

� Removal of cables, feasible methods include: 

o Pulling the cable out of seabed using a grapnel; 

o Pulling an under-runner using a steel cable to push the 

electrical cable from the seabed; or 

o Jetting the seabed material. 

� Transport cables to an onshore site where they will be processed for 

reuse/recycling/disposal. 

13.8.3 Impacts will be similar to those described for the construction phase (physical 

disturbance, smothering and re-mobilisation of contaminants), although these 

are likely to be lower in magnitude. The main impact associated with piling 

during the construction would not occur during the decommissioning phase. 



13.8.4 As discussed for operation the presence of WTGs will increase habitat 

heterogeneity and has the potential to aggregate fish species by providing 

shelter and food (see below). The removal of these structures during 

decommissioning would result in loss of habitat for certain fish and 

crustacean species. The disturbance impact associated with the 

decommissioning are assessed as being of negligible significance based on 

the low sensitivity of the species and magnitude of the impact. 

13.8.5 Over time the original habitats lost in the footprint of the infrastructure will 

redevelop. Overall, the long term effect of this would be to return the area to 

its former state in terms of fish community assemblages and the impact 

would be neutral with no impact on the long term. 

Loss of prey resource 

13.8.6 As discussed in Chapter 12, during operation the WTGs would become 

colonised by a wide range of benthic species which in turn would provide a 

food resource for other species. While there would be a loss of prey 

resource (and habitat) over the short term this impact would be neutral with 

no impact over the long term as the fish and crustacean community 

composition would return to their former state. 

13.9 Inter-relationships 

13.9.1 The inter-relationships between the fish and shellfish resource and other 

physical, environmental and human parameters are inherently considered 

throughout the assessment of impacts (Sections 13.6 and 13.7) as a result 

of the receptor lead approach to the assessment. For example, the 

availability of fish and shellfish resources has the potential to be influenced 

by changes in water quality, suspended sediments and benthic communities 

as a result of the effects of the proposed development. The potential impacts 

as a result of this indirect effect have been discussed within this chapter 

based on the findings of the assessments made in Chapter 10 Marine Water 

and Sediment Quality and Chapter 12 Marine and Intertidal Ecology. 

13.9.2 Similarly any impact on fish and shellfish resources from the proposed 

development has the potential to impact on a number of other receptors, 

such as commercial fisheries, marine mammals and ornithology. The 

information provided in this Chapter is used in turn by these relevant receptor 

lead Chapters to establish the potential for and significance of inter-related 

impacts. 

13.9.3 Table 13.15 summarises those inter-relationships that are considered of 

relevance to natural fish and shellfish resources and, identifies where within 

the ES these relationships have been considered. 



Table 13.15 Fish and shellfish resource inter-relationships 

Inter-relationship Section where addressed Linked Chapter 

Construction 

Indirect impacts due to the 

loss of habitat and benthic 

prey resource during 

construction 

Indirect impacts to fish and 

crustacean from physical 

disturbance to intertidal and 


Indirect impacts from loss of 

fish as a prey resource 

Impact on fish resource from 

changes in water quality 

Operation 

Influence of increased 

habitat complexity and 

benthos on fish aggregation 

during operation and 

protection from fishing effort 

due to 50m exclusion zones 

around structures 

Indirect impact of loss of 

prey resource resulting from 

changes in current regime 

and indirect effects on 

subtidal ecology during the 

operational phase 

Section 13.6 Influencing parameter: 

Chapter 12 Marine and 

Intertidal Ecology 



Intertidal Ecology 

Section 13.6 Affected parameter: Chapter 

11 Offshore Ornithology, 

Chapter 14 Marine Mammals 

and Chapter 15 Commercial 

Fisheries 


Chapter 10 Marine Water 

and Sediment Quality and 

Chapter 9 Physical 

Environment 



Intertidal Ecology and 

Chapter 15 Commercial 

Fisheries 


Chapter 9 Physical 

Environment and Chapter 

12 Marine and Intertidal 

Ecology 



13.9.4 Chapter 29 Assessment of Inter-relationships provides a holistic overview 

of all of the inter-related impacts associated with the project. 

13.10 Cumulative Impacts 

13.10.1 A cumulative impact can only occur where a project aspect is identified as 

having an impact on a receptor in isolation. 

13.10.2 The main impacts identified during the construction (Section 13.6) operation 

(Section 13.7) and decommissioning phases (Section 13.8) of the GWF 

project which have the potential to result in cumulative effects are considered 

to be the impacts associated with construction noise and in particular piling 

activities and also habitat loss which are discussed in Chapter 12. 

13.10.3 Cumulative impacts associated with the GWF project could occur on a 

number of levels: 

� Interactions between different aspects of the GWF project with other 

wind farms; and 

� Interactions with other activities occurring in the region. 

13.10.4 The following paragraphs provide an assessment of the potential for 

cumulative impact over these varying levels. The cumulative impact 

assessment is based on the impacts identified above and therefore the worst 

case scenarios for the GWF project outlined in Table 13.9. The cumulative 

modelling with London Array has been carried out on the worst case 

assumption of 7m monopile foundations. 

GWF and other wind farms 

13.10.5 The existing and planned wind farms in the Outer Thames Estuary area 

which could contribute to cumulative effects when considered alongside the 

GWF are shown in Figure 13.25. Distances presented in Table 13.15 are for 

the nearest (minimum) distances and relate to boundary limits rather than 

specific features or structures within each site. Table 13.16 also presents 

the predicted construction timetables for the sites within the Thames area. 

Table 13.16 Distances (km) of Outer Thames wind farm sites from GWF 

Project Details Status Distance From 

Galloper Site 

(km) 

Predicted 

Construction 

Period 

Galloper EIA Stage N/A Total maximum 

piling duration of 

39 months, 

notionally 

assuming an 

earliest Q2 or Q3 



Project Details Status Distance From 

Galloper Site 

(km) 

Predicted 

Construction 

Period 

2015 

commencement 

within the 56 

month offshore 

construction 

window 

Greater Gabbard In construction 0 2009 - 2012 

East Anglia ONE Offshore 

Wind Farm 

Zonal Assessment 

and Scoping for 

Project ONE 

25.2 Project ONE to 

commence at 

earliest in 2015 

London Array I In construction 24.3 2011 - 2012 

London Array II Consented 15.1 2014 - 2015 

Thanet Operational 37 Operational 

Gunfleet Sands I Operational 42.6 Operational 

Gunfleet Sands II Operational 40 Operational 

Gunfleet Sands Extension In planning 46.4 2011 - 2012 

Kentish Flats Operational 61.6 Operational 

Kentish Flats Extension EIA Stage 61.5 2013 -2014 

Source: Construction times supplied via www.4coffshore.com 





Noise impacts 

13.10.6 Evidence (Chapter 5 and Sections 13.6 and 13.7) would suggest that the 

only possible noise source from offshore wind farms that has the potential to 

extend sufficient geographical distance as to overlap with that of another 

wind farm project would occur during foundation pile driving activity 

associated with the construction phase. 

13.10.7 Potential for cumulative underwater noise impacts to affect fish, especially in 

relation to spawning activities or spawning grounds, is therefore, dependent 

on two or more projects undertaking pile driving simultaneously and/or two or 

more projects undertaking pile driving activities over consecutive spawning 

periods thereby causing longer term disruption. 

13.10.8 While several offshore wind farms are planned for future construction in the 

region (Table 13.16), following a review of the anticipated construction 

schedules for these projects, only four projects were identified as potentially 

coinciding with the GWF project. These are East Anglia ONE (although there 

is a significant degree of uncertainty associated with the project timescale), 

the Kentish Flats Extension, London Array II (also subject to some 

uncertainty) and the Gunfleet Sands Extension. Phase II of the London Array 

project is currently thought to have the greatest potential to coincide with the 

GWF construction and also have a direct overlap with East Anglia ONE 

(although to a lesser extent given the uncertainty regarding construction 

programme for the latter). It is worth noting the uncertainty associated with 

the construction of London Array Phase II since this can only proceed if 

conditions relating to the significant barrier effects on red-throated divers can 

be resolved (see Chapter 11). 

13.10.9 Two main areas of potential impact have been identified as: 

� Those relating to the cumulative noise dose and increased spatial 

impact extent of concurrent piling operations at different wind farm 

locations; and 

� The impact of different projects piling over consecutive years and 

causing continued disruption to spawning fish species over 

consecutive spawning periods. 

13.10.10 The assessment of the cumulative impact of concurrent piling has been 

carried out in two ways to give a broader picture of the impacts that may 

occur; a behavioural impact assessment for piling at two locations, analysing 

where the 90dBht contours overlap, and an assessment based on perceived 

noise dose criteria. 

13.10.11 Concerns were raised during consultation (see Table 13.1) regarding the 

potential cumulative underwater noise impacts associated with the proposed 

GWF and East Anglia ONE. At the time of writing no specific project 

information was available for East Anglia ONE in terms of foundation types, 

pile diameter etc., with which to undertake cumulative noise modelling. 



However, in recognition of potential overlap of construction activity a 

discussion of potential impacts has been undertaken. In terms of assessing 

the worst case cumulative piling noise impacts, it is worth noting that in the 

absence of further information on the construction of the East Anglia ONE 

project a broad assumption of similar foundation types (to that considered for 

GWF) has been made in order to allow for a qualitative assessment to be 

made albeit with inherent uncertainties acknowledged. 

13.10.12 The cumulative contour plots for herring, cod and dab are shown in Figure 

13.29 to 13.31. 









13.10.13 The data for Phase II of the London Array project and proposed GWF project 

indicate that for all the species considered, with the exception of dab (sole), 

there could be a degree of overlap and, therefore, pile driving at these two 

locations could be considered to have a net cumulative impact in terms of the 

total area in which animals may be exposed to aversive levels of underwater 

noise. 

13.10.14 In summary, under some circumstances the areas around two simultaneous 

pile driving operations at different sites may converge. In this case, the 

excluded area may increase over that for one pile driving operation, and its 

ability to block movement may increase accordingly (Subacoustech, 2011). 

13.10.15 While the worst case scenario for piling driving at GWF is four hours per 

monopile, it should be noted, however, that pile driving is intermittent and 

based on monitoring at GGOWF is more likely to take between one to two 

hours to install. As such the possibility of a temporal overlap occurring 

between piling at the two sites is likely to be small. 

13.10.16 The cumulative noise assessment (Subacoustech, 2011) has also included 

received Noise Dose and SEL methodologies (these methodologies are 

outlined in more detail within Chapter 5) to assess the auditory injury zone in 

the vicinity of an impact piling operation. This study used the approach that 

the degree of hearing damage depends upon both the received level of 

noise, and the time of exposure to it. 

13.10.17 The results indicated that, for herring, the critical range between monopiles at 

which point the cumulative noise dose increases above 90dBht LEP,D is 7km 

and, in the case of dab, it is 50m. In the case of these species, therefore, the 

data indicate that if two monopiles were being installed at locations closer 

than the above ranges, individuals may not be able to swim out of the 

auditory injury zone before receiving a noise dose that is likely to cause 

hearing impairment. The closest locations for two piles at the London Array 

site and the proposed GWF site are approximately 14km apart. Similarly, the 

distance to East Anglia ONE is over 25km. 

13.10.18 The predicted impact ranges for the assessment were similar to those 

predicted for the 130dBht perceived level at which traumatic hearing damage 

from a single pile driving event would be expected, therefore, indicating that 

any possibility of hearing damage would most likely be as a result of 

underwater noise from the nearest pile to the animal rather than a cumulative 

effect. These data therefore suggest that the cumulative noise dose from 

impact pile driving operations at the London Array, and GWF is unlikely to 

increase the likelihood of auditory injury. This would also indicate that based 

on similar foundation types and given the distance to East Anglia ONE 

location (>25km) cumulative noise dose impacts increasing auditory injury 

are unlikely to occur. 

13.10.19 If the pile driving activities were carried out at two wind farm sites 

concurrently, the overall area of impact and extent of behavioural effects and 

potential temporary displacement of fish species would be increased. 



Depending on the spatial coverage of the impact this could increase the 

magnitude of any impact. As discussed previously, areas indicated as 

spawning grounds by Coull et al., and Pawson for species such as herring 

and sole are in close proximity to the proposed GWF. However, since the 

noise effects ranges/footprints are only marginally greater than for GWF in 

isolation and more importantly spatially separate from the main herring 

grounds (and to some extent the highest intensity sole grounds), the effects 

would be no more significant than for GWF alone. Furthermore, London 

Array also has a piling restriction in place which would preclude the potential 

for cumulative impacts on the sole spawning grounds. As such the impact is 

assessed as minor adverse. 

13.10.20 While pile driving operations disrupting a single species spawning season 

may not necessarily have potential long term or wider scale population 

effects, if consecutive wind farm projects continually disrupt spawning 

behaviour for key spawning sites over consecutive years reduced spawning 

success and subsequent population recruitment could occur. 

13.10.21 The current level of information and certainty on construction timescales and 

in particular piling programmes for other wind farm projects is limited at 

present and only indicative timescale are known at this time (see Table 

13.16). These current timescales suggest that piling activities could occur 

during 2011 and 2012 for the Gunfleet Sands Extension and London Array 

Phase I, 2013 and 2014 for the Kentish Flats Extension and London Array 

Phase II, 2015 to 2019 for GWF and from 2015 onwards for East Anglia 

ONE. To put these into perspective it is worth noting that the Gunfleet Sands 

Extension consists of only 2 WTGs, the Kentish Flats Extension between 10 

and 17 WTGs and the London Array construction are subject to a sole 

spawning restriction. The Kentish Flats and Gunfleet Sands Extensions 

would not overlap spatially with the Downs herring spawning grounds and in 

terms of sole given the small number of turbines the actual piling duration 

would be very short and in order to have any significant impact on sole and 

would need to coincide with their spawning periods. 

13.10.22 The London Array II project, GWF and East Anglia ONE could potentially 

have consecutive impacts on the Downs herring spawning stocks from 2014 

to 2016. As discussed previously, the main Downs herring spawning 

grounds are those located in the eastern English Channel. These would not 

be impacted by the consecutive piling events. The sensitivity of spawning 

herring to noise impacts is considered to be high. As for the arguments 

discussed in Section 13.6 above, the magnitude would remain negligible as 

this is based on the impact not extending to the Downs spawning grounds in 

the eastern English Channel. While the duration of the impact would extend 

from one year to potentially three, this increase in duration is not significant 

enough to warrant increasing the overall magnitude. Furthermore, the 

likelihood of consecutive piling disruption over the Downs herring spawning 

season (November to January) is considered to be low based on the 

potential restrictions cause by weather windows, variations in construction 

programs etc. The overall impact significance of consecutive piling is 

therefore minor adverse. 



13.10.23 Based on the discussion above relating to the small number of piles and 

restrictions associated with the London Array it is considered that potential 

consecutive impacts to the inshore Thames sole spawning grounds over the 

period 2011 to 2016 would not occur. Greater Gabbard OWF also undertook 

piling in 2009/2010; however, this project was subject to spawning 

restrictions which avoided the sole spawning period. 

13.10.24 Sole are considered to be relatively insensitive to noise and while their 

overall sensitivity has been assessed as medium (see Section 13.6) the 

actual extent of behavioural impacts are generally localised (see Figure 

13.31). The potential for the different wind farm projects to continually disrupt 

the same spawning areas is therefore unlikely, especially given the size of 

the sole spawning area available in the Thames Estuary and license 

conditions associated with some of the other inshore developments 

precluding piling during the sole spawning season. While the duration would 

extend slightly from that discussed in Section 13.6 it is considered that the 

magnitude of the impact would remain low based on the limited spatial 

overlap. The significance of the impact is therefore assessed as minor 

adverse. 


13.10.25 Based on the piling noise and cumulative piling noise discussions above it is 

considered that there is no significant risk of likely cumulative effect on the 

herring or sole spawning grounds as a result of the proposed GWF project. 

13.10.26 Further discussions are ongoing with the regulators to establish the actions 

that are required in order to bring any necessary restrictions in line with the 

anticipated impacts associated with the proposed GWF development. 

13.10.27 As discussed previously mitigation in the form of soft start piling will be 

incorporated into construction procedures. However, while such measures 

would reduce the impacts associated with lethal and physical injury, once 

piling reaches full blow force the behavioural impact ranges would remain 

unchanged compared to the pre soft start predictions. Despite the lack of 

significant impact predicted on herring or sole spawning grounds, further 

precautionary mitigation is applied through the commitment to restrict piling 

activity to a maximum overlap of two spawning seasons for each of the two 

(herring and sole) species over the 56 month construction window. This 

effectively imposes a piling restriction for two of the four potential seasons 

that occur within such a window (based on a total maximum piling duration of 

39 months, notionally assuming an earliest Q2 or Q3 2015 commencement 

within the 56 month offshore construction window). 

13.10.28 Given the above mitigation it is considered that likelihood for significant 

potential cumulative impact is low and consequently the impact assessed of 

negligible significance. 

13.10.29 It is anticipated that should the construction programme slip beyond 2019 the 

same spawning overlap principles discussed above would apply with no 



piling occurring during key spawning periods assuming that two overlaps had 

already occurred. 

EMF impacts 

13.10.30 During consultation the EIFCA raised concerns about the potential 

cumulative EMF effects associated with the crossing point of the GWF and 

East Anglia ONE export cables (See Figure 30.1). Given that the extent of 

any EMF effects will be very localised it is not anticipated that a single 

crossing point will have any significantly wider cumulative impacts and would 

not impact wider species populations. Given the effects would be associated 

with a single crossing point and therefore localised the impact magnitude is 

assessed as negligible. As for EMF effects discussed above the receptor 

sensitivity is considered to be high and the overall impact significance is 

assessed as minor adverse. 

GWF and other activities 

13.10.31 There are limited additional human activities occurring within the vicinity of 

the GWF project site, with the exception of aggregate extraction, which is 

discussed in more detail in Chapter 18 Other Human Activity and 

commercial fishing activities (Chapter 15). 

13.10.32 As in Section 13.6, the construction related impacts at GWF have the 

potential to affect the Downs herring spawning grounds. The Downs herring 

spawning grounds extend into the East English Channel; an area subject to 

extensive aggregate dredging operations. A series of assessments on the 

effects of aggregates dredging on the East Channel spawning grounds have 

been undertaken behalf of the East Channel Association (RPS, 2011). 

13.10.33 The study concluded that the proportion of the total herring spawning habitat 

within the East English Channel potentially impacted by aggregate extraction 

was extremely small, with less than one third of a percent of the potential 

herring spawning habitat in the East English Channel impacted, either 

directly or indirectly (RPS, 2011). The data also indicated that the spawning 

activity within the area has not been noticeably reduced since the 

commencement of dredging. In addition the direct impacts to herring 

spawning are limited at some licensed areas by restrictions to dredging 

during the herring spawning season of November to February. Furthermore, 

the areas of very high spawning potential are located to the south of the 

aggregates extraction sites which are not anticipated to be impacted either 

directly or indirectly by aggregates extraction activities (RPS, 2011). Given 

the present level of information available on the impacts associated with 

GWF there is not anticipated to be any significant cumulative impact to the 

Downs herring spawning grounds. 

13.10.34 Sizewell nuclear facility has a number of existing marine components 

(namely the intake and outlet cooling water pipes). Intake structures of 

power stations are known to entrain and kill fish species (Turnpenny & 

Taylor, 2000). Although the Sizewell project is listed with the IPC, there has 

been no scoping exercise undertaken and no details of the construction 



programme are available. A formal application to the IPC is not expected 

until 2012 at the earliest, with construction unlikely to be possible until 2015. 

It is anticipated that similar marine intake structures would be constructed to 

replace the existing intakes. It is anticipated that, as for other new build 

power station projects, the regulators would require stringent screening and 

fish impingement and entrainment mitigation devices to be employed 

including the use of acoustic deterrents and fish return systems in 

accordance with the best available techniques. This would ensure that the 

new intakes would entrain significantly less fish species and have higher 

survival rates than the current existing structures. Based on the localised 

and inshore nature of any impacts and mitigation associated with these 

structures, there is not anticipated to be any significant cumulative interaction 

with the GWF activities. 

13.11 Transboundary Effects 

13.11.1 This Chapter has considered the potential for transboundary effects to occur 

on marine water and sediment quality as a result of the construction, 

operation or decommissioning of the proposed GWF project. In all cases it is 

concluded that the potential impacts arising, by virtue of the predicted spatial 

and temporal magnitude of the effects, would not give rise to significant 

transboundary effects on the environment of another European Economic 

Area (EEA) member state. A summary of the likely transboundary effects of 

the proposed GWF are summarised in Chapter 31 Transboundary Effects. 

13.12 Monitoring 

13.12.1 NPS EN-3 states that ecological monitoring may be appropriate in order to 

identify the actual impacts so that where appropriate adverse effects can be 

mitigated. GWFL propose to undertake underwater noise monitoring during 

the installation of the largest four WTGs in order to verify the noise modelling 

carried out by Subacoustech (see Technical appendix 13.B). While the 

present evidence clearly shows that the mains Downs spawning ground is 

currently located in the East English Chanel, GWFL recognise that, while it is 

considered unlikely based on the trends since the 1970’s the recolonisation 

of the Southern Bight spawning grounds could occur prior to piling works 

commencing. Prior to, and during the period of construction GWFL will 

undertake (subject to agreement with the regulators) a yearly analysis of the 

IHLS herring larval data in order to assess the state of spawning on the 

Downs herring spawning grounds. If evidence of recolonisation was found 

(within the relevant timeframe), GWFL would consult with the regulators in 

order to ensure appropriate mitigation measures were put in place, this might 

include piling restrictions if deemed necessary. 

13.12.2 During Section 42 consultation the Eastern Inshore Fisheries and 

Conservation Authority (EIFCA) suggested that monitoring should be carried 

out to establish the impact of EMF (Table 13.1). Based on the current 

knowledge no specific monitoring programme is proposed for GWF. 

However, the FEPA licence condition for GGOWF relating to EMF states that 

the Licence Holder must provide information on the attenuation of field 



strengths associated with cables, shielding and burial depth and relate these 

to the outputs from COWRIE sponsored studies. If this shows the field 

strengths are sufficient to have potentially detrimental effect further biological 

monitoring and mitigation may be required to further investigate the effect. 

Given the adjacent location of the proposed GWF export cable corridor and 

analogous cable specifications (between the two projects), the results from 

the GGOWF will be directly applicable to GWF, providing further information 

on EMF to help inform the industry and also establish if further monitoring is 

required for GWF. 

13.12.3 The requirement for, and detail of, any further pre and post construction 

monitoring at GWF will be established through consultation with the MMO 

and Cefas at least four months prior to any (pre-construction) works 

commencing. 

13.13 Summary 

13.13.1 This Chapter of the ES has provided a characterisation of the existing fish 

and shellfish resource based on both existing and site specific survey data, 

which has established that communities present are indicative of the region 

and occur over broad extents throughout the Outer Thames Estuary and 

southern North Sea. 

13.13.2 Table 13.17 provides a summary of the predicted impact on marine and 

intertidal ecology. The impacts represent the maximum potential adverse 

impact as a result of having assessed the worst case (development) scenario 

for each receptor. Therefore, the predictions made would not be worse 

(more adverse) should any other development scenario (in line with those 

provided in Chapter 5), to that assessed within this Chapter, be taken 

forward in the final scheme design. 

Table 13.17 Summary of impacts 

Description of 

Impact 

Construction Phase 

Noise and 

vibrations - Lethal, 

physical and 

traumatic auditory 

injury effects 

Noise and 

vibrations – 

behavioural 

responses 

Impact 

significance 

Minor 

adverse - 

negligible 

Minor 

adverse - 

negligible 

Mitigation Measures Residual Impact 

Soft start piling 

Piling activity will be restricted to 

a maximum overlap of two 

spawning seasons for herring 

and sole species over the 56 

month construction window. 

Minor adverse - 

negligible 


Final Report Chapter 13 - Page 134 October 2011 

N/A


Impact 

Physical 

disturbance of 

intertidal and 


Indirect loss of fish 

as a prey resource 

Suspended 

sediment 

concentrations 

Re-mobilisation of 

contaminated 

sediments 

Impacts due to loss 

of habitat and 

benthic prey 

resource 

Operation Phase 

Operational noise 

and vibration 

Impact 

significance 


Negligible N/A N/A 





Negligible 

EMF Minor 

adverse 

Aggregation effects Negligible 

beneficial 

Indirect impact of 

loss of prey 

resource and 

habitat from 

changes in current 

regime 

Decommissioning 

N/A N/A 

Best practice measures 

including burial to a 

representative average 

minimum burial depth of 0.6m. 

N/A N/A 


Loss of habitat Negligible – N/A N/A 

Minor adverse 




Impact 

Loss of prey 

resource 

Impact 

significance 

no impact 


No impact N/A N/A 

13.13.3 Concurrent and consecutive pile driving between GWF and other wind farm 

are not anticipated to have any cumulative noise impacts on sole and the 

Downs herring spawning grounds as there is limited scope for continued 

disturbance over consecutive years given the sole spawning restrictions 

already in place for London Array and GGOWF and the limited impacts 

associated with the installation of the Gunfleet Sands and Kentish Flats 

Extension projects. Consequently no significant cumulative impacts are 

predicted. 



13.14 References 

Andersson, M. H. (2011). Offshore wind farms – ecological effects of noise 

and habitat alteration on fish. Doctoral dissertation 2011. Department of 

Zoology, Stockholm University. 

Andriguetto-Filhoa, J.M., Ostrenskya, A., Pieb, M.R., Silvac, U.A. & Boegerb, 

W.A. (2005). Evaluating the impact of seismic prospecting on artisanal 

shrimp fisheries. Continental Shelf Research. 25: 1720–1727 

Atema, J. (1986). Review of sexual selection and chemical communication in 

the lobster Homarus americanus. Canadian Journal of Fisheries and Aquatic 

Science, 43: 2283-2390. 

Ball, R.E. (2007). Electroreception in embryos of the thornback ray, Raja 

clavata. Unpublished MSc thesis. Department of Natural Resources, 

Integrated Earth System Sciences Institute, Cranfield University. 

Barnes M. (2008). Microstomus kitt. Lemon sole. Marine Life Information 

Network: Biology and Sensitivity Key Information Sub-programme [on-line]. 

Plymouth: Marine Biological Association of the United Kingdom. [cited 

10/02/2011]. Available from: 

 

Bannister, R.C.A., Addison, J.T., and Lovewell, S.R.J. (1994). Growth, 

movement, recapture rate and survival of hatchery-reared lobsters (Homarus 

gammarus Linnaeus, 1758) released into the wild on the English East Coast. 

Crustaceana, 67: 156-172. 

Baynes, S.M.; Howell, B.R.; Beard, T.W.; Hallam, J.D. (1994). A description 

of spawning behaviour of captive Dover sole, Solea solea (L.) Neth. J. Sea 

Res. 32(3-4): 271-275 

Bromley P.J., (2003). The use of market sampling to generate maturity 

ogives and to investigate growth, sexual dimorphism and reproductive 

strategy in central and south-western North Sea sole (Solea solea L.). ICES 

Journal of Marine Science, 60: 52–65. 2003 doi:10.1006/jmsc.2002.1318. 

Bolle LJ, de Jong CAF, Biermans S, de Haan D, Huijer, T, Kaptein D, 

Lohman M, Tribuhl S, van Beek P, van Damme CJG, van den Berg FHA, van 

der Heul J, van Keeken O, Wessels P, Winter E (2011). Shortlist Masterplan 

Wind. Effect of piling noise on the survival of fish larvae (pilot study).IMARES 

report. 

Booman, C., Dalen, H., Heivestad, H., Levsen, A., van der Meeren, T. & 

Toklum, K. (1996). Effekter av luftkanonskyting pa egg, larver og ynell. 

Undersekelser ved Hauforskningstituttet ogtoclgisk Laboratorium, Universitet; 

Bergen. Fisken og Havet, 3. 



Burt, G.J. and Milner, R.S. (2008). Movements of sole in the southern North 

Sea and eastern English Channel from tagging studies (1995 - 2004). Sci. 

Ser. Tech. Rep., Cefas Lowestoft, 144: 44pp. 

Cefas (2004) Offshore wind-farms: guidance notes for EIA in respect of 

FEPA and CPA requirements. Prepared by the Centre for Environment, 

Fisheries and Aquaculture Science (Cefas) on behalf of the Marine Consents 

and Environment Unit (MCEU). Version 2 – June 2004 

Cefas (2010a). Mapping spawning and nursery areas of species to be 

considered in Marine Protected Areas (Marine Conservation Zones) Project 

Code: MB5301. August 2010. 

Cefas (2010b). Strategic Review of Offshore Wind Farm Monitoring Data 

Associated with FEPA Licence Conditions. Project ME1117 

Centre for Marine and Coastal Studies (CMACS) (2010). Galloper Offshore 

Wind Farm. Benthic Survey Technical Report 2010. Prepared for OSIRIS 

PROJECTS (NRL and SSER). Included within Appendix 12.A. 

Child A. R., Howell B. R., and Houghton R. G. (1991). Daily periodicity and 

timing of the spawning of sole, Solea solea (L.), in the Thames estuary. ICES 

J. Mar. Sci. (1991) 48(3): 317-323 doi:10.1093/icesjms/48.3.317. 

CMACS (2003) A baseline assessment of electromagnetic fields generated 

by offshore wind farm cables. COWRIE Report EMF - 01-2002 66. 

Corten, A. 2001. The role of "conservatism" in herring migrations. Reviews in 

Fish Biology and Fisheries, 11(4): 339 361. 

Coull, K.A., Johnstone, R., and S.I. Rogers. 1998. Fisheries Sensitivity Maps 

in British Waters. Published and distributed by UKOOA Ltd. 

Daan, N., Hislop, J.R.G., Lahn-Johannessen, J., Parnell, W.G., Scott, J.S., 

and parre, P. 1980. Results of the International O-group Gadoid Survey in 

the North Sea, 1980. ICES CM, G:5. 

Defra (2010). Eel Management plans for the United Kingdom Thames River 

Basin District. Date published: March 2010. 

Department for Business Enterprise and Regulatory Reform BERR (2008). 

Review of cabling techniques and environmental effects applicable to the 

offshore wind farm industry. Technical Report 

Dickey-Collas, M., L. J. Bolle, et al. (2009). Variability in transport of fish eggs 

and larvae. II. Effects of hydrodynamics on the transport of Downs herring 

larvae. Marine Ecology-Progress Series 390: 183-194. 



Dinter, W.P. (2001). Biogeography of the OSPAR Maritime area, A synopsis 

and synthesis of biogeographical distribution patterns described for the 

North-East Atlantic. Bundesamt für Naturschutz (BfN), 167 pp. 

Eastwood, P.D.; Meaden, G.J. (2000). Spatial modelling of spawning habitat 

suitability for the sole (Solea solea L.) in the eastern English Channel and 

southern North Sea. C.M. - International Council for the Exploration of the 

Sea, CM 2000(N:05). ICES[S.l.]. 18 pp 

ECA and RPS Energy. 2010. East English Channel Herring Spawning 

Potential Assessment. Volume 1, Issue 1 (Rev 1). 

Ellis J.R., Burt G.J., Cox L. P. N., Kulka D.W., and Payne. A.I.L (2008). The 

status and management of thornback ray Raja clavata in the south-western 

North Sea Theme Session K. Small scale and recreational fisheries surveys, 

assessment, and management ICES CM 2008/K:13, 45 pp. 

Ellis, J.R., Cruz-Martinez, A., Rackham, B.D. and Rogers, S.I. (2005). The 

distribution of chondrichthyan fishes around the British Isles and implications 

for conservation. Journal of Northwest Atlantic Fishery Science, 35: 195–213. 

Ellis, J. R. and Keable, J. (2008). The fecundity of Northeast Atlantic spurdog 

(Squalus acanthias L., 1758). ICES Journal of Marine Science, 65: 979–981. 

Ellis, J. R. & Shackley, S.E. (1997). The reproductive biology of Scyliorhinus 

canicula in the Bristol Channel, U.K. Journal of Fish Biology, 51:361–372. 

Erftemeijer PLA, van Beek JKL, Bolle LJ, Dickey-Collas M, Los HFJ (2009) 

Variability in transport of fish eggs and larvae. I. Modelling the effects of 

coastal reclamation. Mar Ecol Prog Ser 390:167-181 

Engås A and Løkkeborg S. (2002), Effects of seismic shooting and vesselgenerated 

noise on fish behaviour and catch rates, Bioacoustics 12, 313-315 

Fisheries Research Services (2011). 

http://www.scotland.gov.uk/Topics/marine/marineenvironment/species/fish/sandeels 

Accessed on 26/03/2011 

Fox, C. J. 2001. Recent trends in stock-recruitment of Blackwater herring 

(Clupea harengus L.) in relation to larval production. – ICES Journal of 

Marine Science, 58: 750–762. 

Fox, CJ, Taylor, M. I. et al. (2008) Mapping the spawning grounds North Sea 

cod (Gadus morhua) by direct and indirect means. Proceedings Royal 

Society B. 275: 1543-1548 

Gardline (2010) Greater Gabbard Offshore Wind Farm Underwater Noise 

Monitoring During Marine Piling, Flour Ltd. Project Ref. 8503 September 

2010 



Gauld, J. 1979. Reproduction and fecundity of the Scottish-Norwegian stock 

of spurdogs, Squalus acanthias (L.). ICES CM 1979/H:54. 9 pp. 

Gill, A.B. & Bartlett, M. (2010). Literature review on the potential effects of 

electromagnetic fields and subsea noise from marine renewable energy 

developments on Atlantic salmon, sea trout and European eel. Scottish 

Natural Heritage Commissioned Report No.401. 

Gill, A. B., Gloyne-Phillips, I., Neal, K. J. & Kimber, J. A. 2005. The potential 

effects of electromagnetic fields generated by sub-sea power cables 

associated with offshore wind farm developments on electrically and 

magnetically sensitive marine organisms - a review. In: Report to 

Collaborative Offshore Wind Research into the Environment (COWRIE) 

group, Crown Estates (unpublished report). 

Gill, A.B., Huang, Y., Gloyne-Philips, I., Metcalfe, J., Quayle, V., Spencer, J. 

& Wearmouth, V. (2009). COWRIE 2.0 Electromagnetic Fields (EMF) Phase 

2: EMF-sensitive fish response to EM emissions from sub-sea electricity 

cables of the type used by the offshore renewable energy industry. 

Commissioned by COWRIE Ltd (project reference COWRIE-EMF-1-06). 

Greater Gabbard Offshore Wind Limited (GGOWL) (2009). Underwater Noise 

Monitoring During Marine Piling. July 2009. 

Greater Gabbard Offshore Wind Limited (GGOWL) (2005) Greater Gabbard 

Offshore Wind Farm Environmental Statement, October 2005 

Hammar, L., Andersson, S., and Rosenberg, R. (2010). Adapting offshore 

wind power foundations to local environment. Published by the Swedish 

Environmental Protection Agency. 

Harris G.S. and Milner N.J. (2006) Sea Trout: Biology, Conservation and 

Management. Proceedings of First International Sea Trout Symposium, 

Cardiff, July 2004. Blackwell Scientific Publications, Oxford, 499pp. 

Hawkins, A. D., and Rasmussen, K. J. 1978. The calls of gadoid fish. Journal 

of the Marine Biological Association, UK, 58: 891–911. 

Holden, M. J. and Meadows, P. S. 1964. The fecundity of the spurdog 

(Squalus acanthias L.). Journal du Conseil International pour l'Exploration de 

la Mer, 28: 418–424. 

Holthius, L.B. (1991). FAO Species Catalogue. Marine lobsters of the World. 

An annotated and illustrated catalogue of species of interest to fisheries 

known to date. FAO Fisheries Synopsis, 125: 13. 

Houghton, R.G., and Harding, D. 1976. The plaice of the English Channel: 

spawning and migration. Journal du Conseil International pour 



l'Exploration de la Mer 36: 229-239. 

Hunter, E., Metcalfe, J.D. and Reynolds, J.D. 2003. Migration route and 

spawning area fidelity by North Sea plaice. Proc. R. Soc. Lond. B 270: 2097- 

2103. 

Hunter, E., Buckley, A.A., Stewart, C. and Metcalfe, J.D. (2005) Migratory 

behaviour of the thornback ray, Raja clavata, in the southern North Sea. 

Journal of the Marine Biological Association of the United Kingdom, 85: 

1095–1105. 

ICES (2003) http://www.ices.dk/products/CMdocs/2003/E/E0903.PDF 

ICES (2010a). ICES-FishMap – accessed online November 2010. 

ICES (2010b). Advice October 2010 - Demersal elasmobranchs in the North 

Sea, Skagerrak, and Eastern Channel. Pp8 

ICES (2010c). Advice November, Revised December 2010. Widely 

Distributed and Migratory Stocks. European eel. 

ICES Marine Environmental Quality Commitee, CM 1996/E:26. 

ICES. 2008. Report of the ICES Advisory Committee 2008. ICES Advice, 

2008. Book 6, 326 pp. 

ICES. 2009. Report of the Herring Assessment Working Group for the Area 

South of 62 N, 17-25 March 2009, ICES Headquarters, Copenhagen. Diane 

Lindemann. 648 pp. 

ICES (2007a) Report of the herring assessment working group for the area 

south of 62°N. ICES CM 615 2007/ACFM:11, ICES, Copenhagen 

ICES (2007b). Report of the Working Group on Elasmobranch Fishes 

(WGEF), 22–28 June 2007, Galway, Ireland. ICES CM 2007/ACFM:27, 318 

pp. 

Jacklin, (1998). Exploratory fishing trials for Buccinum undatumn around the 

Islands of Barra and South Uist in the Western Isles. Consultancy Report No. 

CR144 June 1998. Sea Fish Industry Authority Technology Division 

(SeaFish). 

Kaiser, M. J., Rogers, S. I. & Ellis, J. R. (1999). Importance of benthic habitat 

complexity for demersal fish assemblages. American Fisheries Society 

Symposium, 22: Pp 212–223. 

Kioerboe T, Frantsen E, Jensen C & Nohr, O (1981). Effects of suspendedsediment 

on development and hatching of herring (Clupea harengus) eggs. 

Estuarine, Coastal and Shelf Science, vol. 13, 107-111. 



Kimber J. A. (2008). Elasmobranch Electroreceptive Foraging Behaviour: 

Male-Female Interactions, Choice And Cognitive Ability. School Of Applied 

Sciences. Phd Thesis Cranfield University Academic Years 2005-2008. 

Knight A.P. (1907). The effects of dynamite explosions on fish life. A 

preliminary report. Further contributions to Canadian Biology Being Studies 

from the Marine Biological Station of Canada 1902-1905. 39th Annual Report 

of the Department of Marine and Fisheries, Fisheries Branch. Sessional 

Paper No. 22a, pp. 21-30 

Leonard J.B.K., Summers A.P., and Koob T.J (1999). Metabolic Rate of 

Embryonic Little Skate, Raja erinacea (Chondrichthyes: Batoidea): The Cost 

of Active Pumping. Journal of Experimental Zoology 283:13-18 (1999). 

Malcolm. I.A., Godfrey. J, and Youngson. A.F. 2010. Review of migratory 

routes and behaviour of Atlantic salmon, sea trout and European eel in 

Scotland’s coastal environment: implications for the development of marine 

renewables.. Scottish Marine and Freshwater Science Vol 1 No 14. 

Maitland PS & Hatton-Ellis TW (2003). Ecology of the Allis and Twaite Shad. 

Conserving Natura 2000 Rivers Ecology Series No. 3. English Nature, 

Peterborough. 

Maitland P. (2003). The Status of smelt Osmerus eperlanus in England. 

English Nature Research Reports, Report Number 516. ISSN 0967-876X. 

Marine Management Organisation (MMO) (2011). Commercial Fisheries 

landings data 2006 to 2010 for ICES rectangles 32F1, 32F2 and 33F1. 

Marine Management Organisation (MMO), JNCC, Natural England, 

Countryside Council for Wales and Cefas (2010). Draft Guidance on the 

Assessment of Effects on the Environment and Cultural Heritage from Marine 

Renewable Developments. December 2010. 

Marine Aggregate Levy Sustainability Fund (MALSF) (2009) Outer Thames 

Estuary Regional Environmental Characterisation 

Meyer, C.G., Holland, K.N & Papastamatiou, Y.P. (2004) Sharks can detect 

changes in the geomagnetic field, Journal of the Royal Society Interface, 

(DOI: 10.1098/rsif.2004.0021 First Cite):2pp Uhlmann 1975 

Misund O. A., Aglen A., Hamre J., Ona E., Røttingen I., Skagen D., 

Valdemarsen J. W.Improved mapping of schooling fish near surface: 

comparison of abundance estimates obtained by sonar and echo integration. 

ICES Journal of Marine Science 1996;53:383-388. 

Mueller-Blenkle, C., McGregor, P.K., Gill, A.B., Andersson, M.H., Metcalfe, 

J., Bendall, V.,Sigray, P., Wood, D.T. & Thomsen, F. (2010) Effects of Pile- 



driving Noise on the Behaviour of Marine Fish. COWRIE Ref: Fish 06-08, 

Technical Report 31st March 2010. 

Nedwell J R, Langworthy J and Howell D (2003). Assessment of sub-sea 

acoustic noise and vibration from offshore wind turbines and its impact on 

marine wildlife; initial measurements of underwater noise during construction 

of offshore windfarms, and comparison with background noise. 

Subacoustech Report ref: 544R0423, published by COWRIE, May 2003 

Nedwell J R , Parvin S J, Edwards B, Workman R , Brooker A G and Kynoch 

J E (2007a).Measurement and interpretation of underwater noise during 

construction and operation of offshore windfarms in UK waters. 

Subacoustech Report No. 544R0738 to COWRIE Ltd. ISBN: 978-0-9554279- 

5-4. 

Nedwell J R, Turnpenny A W H, Lovell J, Parvin S J, Workman R, Spinks J A 

L, Howell D (2007b). A validation of the dBht as a measure of the behavioural 

and auditory effects of underwater noise. Subacoustech Report Reference: 

534R1231, Published by Department for Business, Enterprise and 

Regulatory Reform. 

Nedwell, J. R, Edwards, B, Turnpenny, A.W.H, & Gordon, J. (2004). Fish and 

Marine Mammal Audiograms: A summary of available information. 

Subacoustech Report ref: 534R0214. 

Norro, A., Haelters, J., Rumes, B., Degraer, S. (undated). Chapter 4. 

Underwater noise produced by the piling activities during the construction of 

the Belwind offshore wind farm (Bligh Bank, Belgian marine waters). 

Thomsen F, Lüdemann K, Kafemann R, Piper W (2006) Effects of offshore 

wind farm noise on marine mammals and fish, biola, Hamburg, Germany on 

behalf of COWRIE Ltd, Newbury, UK. 

Tollefson R, and Marriage L D. (1949). Observations on the effects of the 

intertidal blasting on clams, oysters and other shore inhabitants. Oregon Fish 

Comm. Res. Briefs 2(1): 19-23 

Turnpenny, A.W.H., Taylor, C.J.L., 2000. An assessment of the effect of the 

Sizewell power stations on fish populations. Hydroe´cologie applique´e 

12, 87e134. 

Rijnsdorp, A.D. 1989. Maturation of male and female North Sea plaice 

Pleuronectes platessa L.). Journal du Conseil International pour l'Exploration 

de la Mer 46: 35-51. 

Rijnsdorp, A.D., Beek, F.A. van, Flatman, S., Millner, R.M., Giret, M. and 

Clerck, R. de. (1992) Recruitment of sole stocks, Solea solea (L.), in the 

northeast Atlantic. Neth. J. Sea Res. 29: 173-192. 



Rogers, S. I. (1992). Environmental factors affecting the distribution of sole 

(Solea solea L.) within a nursery area. Netherlands Journal of Sea Research, 

29, 153-161. 

Rogers S, Stocks R (2001) North Sea fish and fisheries. Department of 

Trade and Industry. Strategic Environmental Assessment—SEA2 Technical 

Report 003—Fish and Fisheries CEFAS. 

Rohlf, N. and Groger, J. (2002) Report of the Herring Larvae Surveys in the 

North Sea in 2002/2003. International Council for the Exploration of the Sea, 

CM 2001/ACFM:12, 10pp 

Schmidt J.O., van Damme C.J.G., Röckmann C., and Dickey-Collas M 

(2009). Recolonisation of spawning grounds in a recovering fish stock: recent 

changes in North Sea herring. SCI. MAR., 73S1, October 2009, 153-157. 

Skaret G., Axelsen B. E., Nøttestad L., Fernö A., Johannessen A.The 

behaviour of spawning herring in relation to a survey vessel. ICES Journal of 

Marine Science 2005;62:1061-1064. 

Skalski J R, Pearson W H, and Malme C I. (1992). Effects of sounds from a 

geophysical survey device on catch-per-unit-effort in a hook-and-line fishery 

for rockfish (Sebastes ssp.). Can. J. Fish. Aquat. Sci. 49, 1357-1365. 

Slotte A, Kansen K, Dalen J, and Ona E. (2004). Acoustic mapping of pelagic 

fish distribution and abundance in relation to a seismic shooting area off the 

Norwegian west coast. Fish. Res. 67, 143-150 

Southall, B. L., Bowles, A. E., Ellison, W. T., Finneran, J. J., Gentry, R. L., 

Greene, C. R. Kastak, D., Ketten, D. R., Miller, J. H., Nachtigall, P. E., 

Richardson, W. J. Thomas, J. A., Tyack, P. L, (2007). Marine Mammal Noise 

Exposure Criteria Aquatic Mammals, Vol 33 (4). 

Subacoustech (2011). Galloper Offshore Wind Farm Project: Underwater 

Noise Impact Assessment. Subacoustech Environmental Report No. 

E218R0120. 

Svetnovidov, A.N. 1986. Gadidae. In: Whitehead, P.J.P., Bauchot, M.L., 

Hureau, J.C., Nielsen, J., and Tortonese, E. (eds.). Fishes of the Northeastern 

Atlantic and the Mediterranean. UNESCO, United Kingdom. 1473 pp. 

Öhman M. C., Sigray P., and Westerberg H. (2007). Offshore Windmills and 

the Effects of Electromagnetic Fields on Fish Ambio Vol. 36, No. 8, 

December 2007. 

Pawson, M.G.(1995). Biogeographical identification of English Channel fish 

and shellfish stocks. Fisheries Research Technical Report, Directorate of 

Fisheries Research, Lowestoft, 99:1–72. 



van Deurs, M., van Hal, R., Tomczak, M.T., Jónasdóttir, S.H. & Dolmer, P. 

2009. Recruitment of lesser sandeel Ammodytes marinus in relation to 

density dependence and zooplankton composition. Mar. Ecol. Progr. Ser. 

381: 249–258. 

Yelverton, J. T., Richmond, D. R., Hicks, W., Saunders, K. and Fletcher, E. 

R. (1975). The Relationship Between Fish Size and Their Response to 

Underwater Blast. Report DNA 3677T, Director, Defence Nuclear Agency, 

Washington, DC. 

Westerberg H, Rönnbäck P & Frimansson H (1996). Effects of suspended 

sediment on cod egg and larvae and the behaviour of adult herring and cod. 

Wheeler, A. 1978. Key to the fishes of northern Europe. London, Frederick 

Warne, 380. 

Wilhelmsson, D., Malm, T., and O¨ hman, M. C. 2006. The influence of 

offshore windpower on demersal fish ICES Journal of Marine Science, 63: 

775e784. 

Wright PJ, Bailey MC (1996) Timing of hatching in Ammodytes marinus from 

Shetland waters and its significance to early growth and survivorship. Marine 

Biology 126:143-152 

Wood, R. J. (1981). The Thames Estuary herring stock. Fisheries Research 

Technical Report No.64, Lowestoft, ISSN 0308-5589.

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