Interim report of the HELCOM CORESET project

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2.7. Fish population abundance
2.8. Mean metric length of key fi sh species
2.9. Fish community diversity
2.10. Proportion of large fi sh individuals in the community
2.11. Abundance of fi sh key trophic groups
2.12. Fish community trophic index
Authors and acknowledged persons of the coastal fi sh indicators: Magnus Appelberg, Jens Olsson, Håkan
Wennhage, Antti Lappalainen, Kaj Ådjers, Markus Vetemaa, Outi Heikinheimo, Adam Leijk, Atis Minde,
Iwona Psuty and all Members of the HELCOM FISH-PRO project.
Introduction
This description of core indicators focuses on the work done in the HELCOM FISH-PRO project (HELCOM
2011). The core indicators identifi ed in the HELCOM CORESET project are meant to apply to a wider set of
species and methodologies, developed elsewhere (e.g. ICES working groups, LIFE+ project MARMONI, etc)
or in the second phase of the CORESET project in 2012. Some elements of that work can be seen in Chapter
4 of this report, where candidate indicators are described.
Description of coastal fi sh indicators
Indeces for coastal fi sh were developed for the following biodiversity levels within D1.
Table 2.11. Proposed core indicators and their links to the MSFD GES criteria.
GES criteria Coastal fi sh Indeces Proposed core indicators
1.2 Species Abundance Index Fish population abundance
1.3 Species Demographic Index Mean metric length of key fi sh species
1.6 Community Diversity Index, Fish community diversity, Proportion of large fi sh
Community Size Index
individuals in the community
1.6 Community Abundance Index Abundance of fi sh key trophic groups
1.7 Community Trophic Index Fish communitytrophic index
Indices for coastal fi sh community status estimate changes over time within one monitoring area. The indices
can potentially also be used for estimating differences among geographic areas, provided that the
same monitoring method is applied in all areas to be compared (HELCOM 2011).
Coastal Fish - Species Abundance Index (D1.2.1)
The index estimates the abundance of a key fi sh species in Baltic Sea coastal areas, such as Perch (Perca
fl uviatilis). Perch is a freshwater species that commonly dominates quantitatively coastal fi sh communities
in the Baltic Sea (Ådjers et al. 2006). As such, areas of good ecological status generally have strong
populations of Perch (Eriksson et al. 2011). The species is a piscivore in the adult stage and an appreciated
target for both small scale commercial fi sheries and recreational fi shing (Swedish Board of Fisheries 2011).
The index refl ects the integrated effects of recruitment and mortality. Recruitment success is expected to
be mainly infl uenced by climate and quality of recruitment habitats. Mortality is infl uenced by fi shing, but
potentially also by predation from apex predators, such as seals, sea birds and fi sh.
Policy relevance: The index will show if the abundance and productivity of Perch is at appropriate level for
supporting coastal ecosystem function, focusing on food provision but also refl ecting the trophic state. In