1. Descriptor 3 for determining Good Environmental Status (GES) under the MSFD was defined as “Populations of all commercially exploited fish and shellfish are within safe biological limits, exhibiting a population age and size distribution that is indicative of a healthy stock”Directive 2008/56/EC, Annex I

2.  methodological standards are defined  methods developed and agreed in the framework of European or international conventions  Criterion 3.1 Level of pressure of the fishing activity  Primary indicator: Indicator 3.1.1 Fishing mortality (F)  Secondary indicator (if analytical assessments yielding values for F are not  available): Indicator 3.1.2 Ratio between catch and biomass index (hereinafter  ‘catch/biomass ratio’)  Criterion 3.2 Reproductive capacity of the stock  Primary indicator: Indicator 3.2.1 Spawning Stock Biomass (SSB)  Secondary indicator (if analytical assessments yielding values for SSB are  not available): Indicator 3.2.2 Biomass indices

3.  Criterion 3.3 Population age and size distribution  Primary indicator: Indicator 3.3.1 Proportion of fish larger than the mean  size of first sexual maturation  Primary indicator: Indicator 3.3.2 Mean maximum length across all species  found in research vessel surveys  Primary indicator: Indicator 3.3.3 95% percentile of the fish length distribution  observed in research vessel surveys  Secondary indicator: Indicator 3.3.4 Size at first sexual maturation

5.  Descriptor 3: Populations of all commercially exploited fish and shellfish  are within safe biological limits,  exhibiting a population age and size distribution that is indicative of a healthy stock. Catch/Biomass ratio Biomass indices Size at first maturation 3. 1 Fishing pressure F Ref level: F MSY 3. 2 Reproductive capacity SSB Ref level: SSB MSY 3. 3 Population age and size distribution 95% percentile of length distribution Prop of fish > mean size of first sexual maturation Mean maximum length across species Criterion Primary indicator Secondary indicator

6. Selection of commercially exploited (shell)fish populations Stocks for which primary indicators and reference levels are available Species for which no reference levels are available Interpretation of GES Assessment of current status in relation to GES Roadmap to the GES assessment process

7. Approach Theoretical concepts, criteria, methodologies for: Selection of commercial species Stocks with analytical assessments Species/stocks with info from monitoring programmes Case Studies: Bay of Biscay/Iberia Baltic SeaCeltic SeasNorth SeaMediterranean Synthesis: Different interpretations of GES Assessment of current status against GES Black Sea

8.  Robust quantitative assessment  Preliminary quantitative assessment  Estimates of fishing mortality / exploitation (F) from catch curves (age / length data)  Trends in catch-per-unit-effort (CPUE) Uncertainty increases

9. % Analytical38 Trends based10 Trends, survey only39 Catch only13 Dr Carl O’Brien 2012  Reduced quality and utility of advice for management

10. The data available are inadequate to:  estimate the current population size; and  the catch resulting from fishing at a desired F.  Advice on catches only?  ICES’ MSY approach calls for a determination of the status of exploitation relative to F MSY and considerations of the stock trend. MSY ? – the maximum average long- term catch that may be taken from a fish stock under prevailing environmenta l conditions Without a radical change in approach … implies that approximately 60% of the 188 (158) stocks will have no useful scientific advice w.r.t. MSY

11.  Issues that ICES has not satisfactorily dealt with:  Data-limited / model-poor stocks  What is F MSY ?  What is the current stock exploitation?  How should we manage future exploitation?

14.  Categorisation of stocks into one of seven basis types: 1) Data rich stocks (quantitative assessments) 2) Negligible landings stocks 3) Stocks with analytical assessments that are treated qualitatively 4) Stocks for which survey indices (or unbiased CPUE) indicate trends 5) Stocks for which reliable catch data are available for short time- series 6) Truly data-poor stocks (landings only) 7) Stocks caught in minor amounts as by-catch Trends/Ref points

15.  Trends/Ref points  relative management advice on the direction and relative scale of the changes required to achieve targets.  Category 4: Stocks for which survey indices (or unbiased CPUE) indicate trends Requirements:  the time series that should be used to determine the status of the stock and provide catch advice.  Category 5: Stocks for which reliable catch data are available for short time-series - Under consideration(further assessments) Category 3:Stocks with analytical assessments that are treated qualitatively Requirements:

16. What are the prospects for the future?  On-going studies;  What is F MSY ?  life history characteristics include, among other things, longevity, fecundity and recruitment variability  What is the current stock exploitation?  Harvest ratio proxies and survey (DCF / FSP) catch curves  How should we manage future exploitation?  simple trend-based rules (survey / catch)