Descriptor 3 Descriptor 3 Fishery indicators V.Raykov,IO-BAS Five main steps were identified to assess Good Environmental Status GES for D3: • Selection of commercially exploited (shell)fish populations relevant to the MSFD (sub)region, or MS-specific sub-division, being assessed with respect to D3; • Identification of stocks that can be assessed in relation to the primary assessment criteria for D3.1 and D3.2; • Determination of criteria to apply to stocks that can not be assessed in relation to the primary assessment criteria, and identification of stocks that can be assessed according to these secondary criteria; • Interpretation of how to define GES for D3 with respect to combining individual
Descriptor 3. Five main steps were identified to assess Good Environmental Status GES for D3: • Selection of commercially exploited (shell)fish populations relevant to the MSFD (sub)region, or MS-specific sub-division, being assessed with respect to D3; - PowerPoint PPT Presentation
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Five main steps were identified to assess Good Environmental Status GES for D3:• Selection of commercially exploited (shell)fish populations relevant to theMSFD (sub)region, or MS-specific sub-division, being assessed with respectto D3;• Identification of stocks that can be assessed in relation to the primary assessmentcriteria for D3.1 and D3.2;• Determination of criteria to apply to stocks that can not be assessed in relationto the primary assessment criteria, and identification of stocks thatcan be assessed according to these secondary criteria;• Interpretation of how to define GES for D3 with respect to combining individualstock assessments at the criteria level, and how to combine criterialevel assessments at the descriptor level;• Assessment of current status in relation to GES.
The ChoiceThe Choice(1) Identification of the
appropriate area; (2) Match of existing spatial
units to that area; (3) Choice of datasource; (4) Choice of time period; (5) Selection criteria.
AssessmentAssessment (1) all indicators with reference levels, (2) not all reference levels, or (3) no
reference levels. For commercial populations that do not have full
assessments scientific monitoring surveys were identified as a potential data source for
calculating some secondary indicators. Three options for determining the current status from trend-
based time series were considered: (1) comparing the recent period mean with
the long-term average (2) comparing the current value of the indicator in relation to
the historic mean setting a threshold based on appropriate percentile of the
Normal distribution; (3) detection of trends.
GESGES GES Interpretation 1: strict interpretation of the
Commission Decision where MSY reference levels are treated as a limit
and thus all stocks must meet the MSY requirement • GES Interpretation 2: the MSY reference levels
are considered as a target and thus half the stocks must achieve the MSY
requirement, and all stocks must achieve precautionary reference levels • GES Interpretation 3: the MSY reference levels
are considered as a target and stocks need to achieve this requirement on
average. This average is calculated accounting for the ‘distance’
individual stocks are above or below the MSY reference level.
For the overall assessmentFor the overall assessmentof Descriptor 3, three approaches were of Descriptor 3, three approaches were considered in the case studies: (1) noconsidered in the case studies: (1) noaggregation across criteria; (2) application of aggregation across criteria; (2) application of the one-out-all-out aggregation rule orthe one-out-all-out aggregation rule or“assessment by worst case”; or (3) application “assessment by worst case”; or (3) application of weights for the different criteria.of weights for the different criteria.
A higher proportion of assessed stocks increases the quality of the GES assessment;species/taxa for which no information is available decreases the quality;length of the time-series (with/without Reference levels);
Stocks for which analyticalstock assessments are conducted the populations
for which only information from monitoring programs is available.
F, SSB
‘catch/biomass ratio’;Biomass indices
Proportion of fish larger than the mean size of first sexual maturationMean maximum length across all species found in research vessel surveys95% percentile of the fish length distribution observed in research vessel surveys
Size at first sexual maturation, whichmay reflect the extent of undesirable genetic effects of exploitation
Issues to be consideredIssues to be consideredAppropriate areas –
divisions/subdivisions?The time period over which the
landings data are considered determines the relative importance of species or species groups;
Threshold for inclusion of species – 1% but in Baltic Sea 0.5% as a threshold for salmon – important but with low catches;
Member States shall, when implementing their obligations under this Directive, take due
account of the fact that marine waters covered by their sovereignty or jurisdiction form an integral
part of the following marine regions:(a) the Baltic Sea;(b) the North-east Atlantic Ocean;(c) the Mediterranean Sea;(d) the Black Sea.
Fishing mortalityFishing mortality
Fmsy,Fmax,F0.1Fmsy,Fmax,F0.1
Based on single species analysis (without ecosystem considerations; Predator-prey relationship);
SSB – single stock estimatinsSSB – single stock estimatins
Species covered by Species covered by monitoring programsmonitoring programs
What is GES?What is GES?
Indicators calculationIndicators calculation
Black SeaBlack SeaIndicator calculations for BG waters
Lmax (mean values) across all species caught in surveys
year No of species (S) L max zone
2012 8.6 21.00 coastal
2012 6.33 22.96 shelf
95% Percentile from L
species year percentile
95% Mean
lenght,cm min max SD CI (95%) zone
Whiting 2012 14.08 10.89 6.00 17.70 1.42 0.01
Sprat 2012 10.23 8.38 6.80 11.20 1.09 0.01
N.mel. 2012 14.11 11.28 6.00 17.70 1.70 0.28
Bluefish 2012 12.91 11.49 9.00 13.50 1.12 0.01
R.mullet 2012 12.60 9.37 5.00 14.40 1.62 0.01
H.mackerel 2012 13.20 9.58 5.50 14.50 2.06 0.01
Coastal
Turbot 2006 62.90 44.81 26.00 76.50 9.94 1.69
2007 58.48 46.19 26.50 74.00 6.77 0.70
2008 57.00 46.28 15.00 71.00 9.26 0.92
2009 63.00 50.92 24.00 74.00 7.55 0.76
2010 67.25 52.44 15.00 73.00 12.18 2.11
2011 65.75 44.34 10.00 68.00 15.72 3.72
Sprat 2012 10.08 8.22 6.00 11.50 1.37 0.01
Whiting 2012 13.92 10.91 5.90 17.00 1.50 0.01
N.melanos 2012 14.36 11.73 6.00 17.00 1.39 0.01
R.mullet 2012 13.03 10.96 9.50 17.00 1.21 0.02
Shelf
Sprat and Sprat and turbotturbotLmean Reference level for the given period of
“healthy stock” conditionHolt (1958), Lopt – which assure max Y/R
if all specimen were caught at the Lopt.Froese et al. (2008) - Yield of the individuals
reached Lopt, won’t affect negatively age structure of the population;
Froese and Sampang (2012) – the stock will have proportion of older individuals,if the mean length in the catch is within the interval : Lopt +/- 10%, i.e. 0.9 Lopt < Lmean < 1.1 Lopt.
For Lopt calculation the following equations is used: