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
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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
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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
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.
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Criterion
Primary
indicator
3. 2
3. 1
Reproductive
Fishing pressure
capacity
F
SSB
Ref level:
FMSY
Ref level:
SSBMSY
3. 3
Population age and
size distribution
Prop of fish > mean size of
first sexual maturation
Mean maximum length
across species
95% percentile
of length distribution
Secondary
indicator
Catch/Biomass
ratio
Biomass
indices
Size at
first maturation
Roadmap to the GES assessment process
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
Approach
Theoretical concepts, criteria, methodologies for:
Selection of commercial species
Stocks with analytical assessments
Species/stocks with info from monitoring programmes
50°N
40°N
30°N
Case Studies:
20°N
20°W
10°W
0°
10°E
20°E
30°E
Regional Seas around Europe
Baltic Sea
North-east Atlantic Ocean
Iceland Sea
Norwegian Sea
Bay of
Biscay/Iberia
Barents Sea
Greater North Sea, incl. the Kattegat and the English Channel
Baltic Sea
North Sea
Celtic Seas
Celtic Seas
Mediterranean
Bay of Biscay and the Iberian Coast
Macaronesia
Mediterranean Sea
Western Mediterranean Sea
Adriatic Sea
Black Sea
Ionian Sea and the Central Mediterranean Sea
Aegian-Levantine Sea
Black Sea
Synthesis:
Different interpretations of GES
Assessment of current status against GES
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Robust quantitative assessment
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Preliminary quantitative assessment
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Estimates of fishing mortality /
exploitation (F) from catch curves (age /
length data)
Uncertainty
increases
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Trends in catch-per-unit-effort (CPUE)
Analytical
Trends based
Trends, survey only
%
38
10
39
Catch only
13
Dr Carl O’Brien 2012
 Reduced quality
and utility of
advice for
management
The data available are inadequate to:
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estimate the current population size; and
the catch resulting from fishing at a desired F.
MSY ? – the
maximum
average longterm catch
that may be
taken from a
fish stock
under
prevailing
environmenta
l conditions
Advice on catches only?
ICES’ MSY approach calls for a determination
of the status of exploitation relative to FMSY and
considerations of the stock trend.
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
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Issues that ICES has not satisfactorily
dealt with:
Data-limited / model-poor stocks
 What is FMSY?
 What is the current stock exploitation?
 How should we manage future
exploitation?
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Categorisation of stocks into one of seven basis types:
1)
2)
3)
4)
5)
6)
7)
Data rich stocks (quantitative assessments)
Trends/Ref points
Negligible landings stocks
Stocks with analytical assessments that are treated qualitatively
Stocks for which survey indices (or unbiased CPUE) indicate
trends
Stocks for which reliable catch data are available for short timeseries
Truly data-poor stocks (landings only)
Stocks caught in minor amounts as by-catch
Category 3:Stocks with analytical
assessments that are treated qualitatively
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Requirements:
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)
What are the prospects for the future?
 On-going studies;
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What is FMSY?
 life history characteristics include, among other things,
longevity, fecundity and recruitment variability
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What is the current stock exploitation?
 Harvest ratio proxies and survey (DCF / FSP) catch
curves
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How should we manage future exploitation?
 simple trend-based rules (survey / catch)