Interim report of the HELCOM CORESET project

on which region-specifi c assessment criteria are defi ned. The reason for choosing this approach is the
known natural regional variability of the disease prevalence (even in areas considered to be pristine), making
it implausible to defi ne generally applicable background/reference values that can uniformly be used
for all geographical units to be assessed. This approach is based on the availability of disease data over a
longer period of time (ideally 10 observations, e.g. in the case of biannual monitoring over a period of fi ve
years) for every geographical area to be assessed. The assessment approach (c) ignores the known regional
differences and involves globally defi ned Assessment Criteria (BAC, EAC; see above) with the consequence
that within-region variation might be dominated by general differences in regional levels. However, by
applying globally defi ned Assessment Criteria, the FDI can also be used for exploratory monitoring in areas
not studied before or for newly installed fi sh disease monitoring programmes after some modifi cation.
The fi nal products of the assessment procedure are:
– graphs showing the temporal changes in mean FDI values in a geographical unit over the entire observation
period; and
– maps in which the geographical units assessed are marked with green, yellow or red smiley faces, indicating
long-term changes (e.g. comparing the past fi ve years to the preceding fi ve-years period) in health
status of the fi sh population (green: improvement of the health status; yellow: indifferent variation; red:
worsening of the health status, reason for concern and motivation for further research on causes),
– maps in which the geographical units assessed are marked with green, yellow or red smiley faces, indicating
trends in health status of the fi sh population during the past fi ve years (green: improvement of the
health status; yellow: indifferent variation; red: worsening of the health status, reason for concern and
motivation for further research on causes),
– maps in which the geographical units assessed are marked with green, yellow or red smiley faces, indicating
the level of the FDI observed at a defi ned point in time (green: below the BAC; yellow: between BAC
and EAC; red: above the EAC, reason for concern and motivation for further research on causes).
The ICES WGPDMO applied the FDI approach and the assessment for the common dab from the North Sea
using ICES fi sh disease data extracted from the ICES Environmental Data Centre twice in 2008 and, using
an extended dataset, in 2009 (ICES 2008, 2009a). The results have been included in the OSPAR QSR 2010
as a case study (OSPAR 2010).
At the 2009 ICES/OSPAR Workshop on Assessment Criteria for Biological Effects Measurements (WKIMC)
and the 2011 meeting of the ICES WGPDMO, Background Assessment Criteria (BAC) and Environmental
Assessment Criteria (EAC) to be used for externally visible diseases, non-specifi c liver histopathology, macroscopic
liver neoplasms and contaminant-specifi c liver histopathology in North Sea dab were proposed
(ICES 2009b, 2011). A common strategy was developed for externally visible fi sh diseases (EVD) and nonspecifi
c liver histopathology (NLH), and a modifi ed strategy was developed for macroscopic liver neoplasm
(MLN) and contaminant-specifi c liver histopathology (SLH). Two strategies are needed because the fi rst two
categories require an external harm entity that is to be controlled by the EAC, while the last two categories
themselves already constitute measures of harm. The approach leading to a BAC for EVD and NLH is
guided by the following considerations:
– No “pristine” reference area is available from which a BC (background concentration) or a BAC could be
obtained and transferred to the ICES area.
– A certain number of diseases in a population seems inevitable as the vast majority of disease rates from
fi sh disease monitoring samples is larger than zero, i.e. has FDI > 0. This suggests using a lower bound
for the mean FDI as BAC (each mean FDI is calculated from data from one cruise, one ICES rectangle).
– Using the smallest historical positive FDI value produces an unstable BAC estimate.
– Preferably a small percentile of the FDI distribution should serve as BAC. The FDI value below which only
a defi ned small proportion (e.g. 10%) of all values lies would be used as BAC.
– A BAC should be derived in this way separately for each species and sex (and the disease category).
– The BACs obtained are considered valid for the whole area from which the basic data originated.
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