Background document
Marine Strategy Framework Directive
2nd meeting on the Descriptor 3+ regarding all commercial exploited fish and shellfish stocks in relation to the Good Environmental Status
09 April 2013, 10:00-18:00
10 April 2013, 10:00-13:00
Conference Centre Albert Borschette, Rue Froissart 36, 1040 Brussels, Room 2D
Title: / Background documentPrepared by: / ICES
Date prepared: / 04/04/2013
Contents
1 Introduction 3
1.1 Presentation: ICES developments (Han Lindeboom) 4
2 MSFD GES Descriptor 3 (D3) 5
2.1 MSFD Descriptor 3 criteria including methodological standards 5
2.1.1 Indicators from stock assessments 6
2.1.2 Indicators from monitoring programs 6
2.1.3 What is GES? 7
2.1.4 Quality of GES assessment 8
2.1.5 Software for calculation indicators and reference values 9
2.1.6 Problems and recommendation 10
2.2 Presentation: Latest developments on Descriptor 3 (Carl O’Brian) 11
2.3 Presentation: Criterion D.3.3 on Healthy age and Size distribution (Gerjan Piet) 11
3 Status of stocks 12
3.1 Implications for prioritisation of management and monitoring 12
3.2 Ecosystem considerations in fisheries advice 13
4 Fisheries related MSFD GES descriptors: D1, D4 and D6 16
4.1 MSFD D1 (Biodiversity) 16
4.1.1 Indicators to assess GES of Diversity 17
4.1.2 Monitoring and implications for research 18
4.1.3 Presentation: D1 biodiversity - Assessment of indicators (Simon Greenstreet) 19
4.2 MSFD D4 (Food webs) 19
4.2.1 Ecosystem Models 20
4.2.2 Relevant spatial and temporal scales 20
4.2.3 Attributes for indication of Food webs status 21
4.2.4 Presentation: Foodweb I - Moving from principles to practice (Stuart Rogers) 21
4.2.5 Presentation: Foodweb II (Stuart Rogers) 21
4.3 MSFD D6 (Habitat) 22
4.3.1 Presentation: D6 Sea floor integrity (Heino Fock) 23
4.3.2 Presentation: D6 Sea floor integrity - Habitat mapping (Pal Buhl Mortensen) 23
4.4 Presentation: Links to EU Biodiversity Strategy (Target 4) (Carl O’Brien) 24
4.5 Presentation: Integrated assessment and Ecosystem overviews (Leonie Dransfeld) 24
1 Introduction
The Marine Strategy Framework Directive (MSFD) of the European Union ([1]) is a comprehensive framework for achieving good environmental status (GES) for European marine ecosystems. The Directive calls for scientifically-based indicators and standards for eleven descriptors of GES. Fishing impacts four MSFD GES descriptors: D3 (Commercially Exploited Fish and Shellfish Stocks), D1 (Biodiversity), D4 (Food webs), and D6 (Sea-floor Integrity).
The ICES approach to fisheries advice integrates a precautionary approach, maximum sustainable yield (MSY), and an ecosystem approach into one advisory framework. The aim is, in accordance with the aggregate of international guidelines, to inform policies for high long-term yields while maintaining productive fish stocks within healthy marine ecosystems.
Countries are committed to an ecosystem based fisheries management which for the EU is implemented through the Common Fisheries Policy (CFP) ([2]) and the MSFD. The CFP aims at MSY ([3]) and also considers the economic viability of fisheries and fair sharing of the fishing possibilities among the EU Member States. The MSFD concerns GES for the marine ecosystem and therefore requires the consideration of fisheries impact also on other ecosystem components than the commercial fish stocks. Thus, there is a need to link CFP and MSFD targets, i.e. to evaluate if fishing at the MSY level for a fishery is economically feasible and at the same time assures that the corresponding exploitation pressure limits the fisheries impact on the ecosystem so that MSFD GES criteria are met.
The EU Biodiversity strategy (COM(2011) 244 final) is aimed at reversing biodiversity loss and speeding up the EU's transition towards a resource efficient and green economy ([4]). In the section on the sustainability of agriculture, forestry and fisheries, the EU Biodiversity strategy mentions that the forthcoming reform of the CAP and CFP and the new Multiannual Financial Framework present opportunities to enhance synergies and maximise
coherence between biodiversity protection objectives and other policies. Regarding fisheries the strategic target 4 reads:
“Fisheries: Achieve Maximum Sustainable Yield (MSY) by 2015. Achieve a population age and size distribution indicative of a healthy stock, through fisheries management with no significant adverse impacts on other stocks, species and ecosystems, in support of achieving Good Environmental Status by 2020, as required under the Marine Strategy Framework Directive.”
The European Commission has requested ICES to help organise this 2nd meeting on the Descriptor 3+ regarding all commercial exploited fish and shellfish stocks in relation to the Good Environmental Status. The aim of the workshop is to present the on-going ICES work related to the MSFD and especially the work on the GES Descriptor 3 (Commercially Exploited Fish and Shellfish Stocks) and the other fisheries related descriptors: D1 (Biodiversity), D4 (Food Webs) and D6 (Sea-floor Integrity) which are all impacted by fishing.
1.1 Presentation: ICES developments (Han Lindeboom)
Summary (Abstract):
ICES is developing supporting knowledge and tools for Ecosystem Based Management and the implementation of the Marine Strategy Framework Directive. Focus areas include indicator and descriptor development, advice for regional seas, harmonisation of monitoring, toolboxes for assessments, data collection and integrated ecosystem approaches. Many ICES expert groups, which are open to all interested experts, are suited and ready to supply data and background information for advice on descriptors and drivers of change. The important role ICES can play in collecting and storing of international environmental data, including the need for integrated monitoring, will be presented. The possible way towards integrated ecosystem assessments and advice will be discussed.
The presentation will give an overview of on-going and planned ICES activities and introduce the workshop topics.
2 MSFD GES Descriptor 3 (D3)
The following is a synthesis of the recommendations from scientific work to provide guidance to support EU Member States (MS) in the implementation of the MSFD GES Descriptor 3 ([5],[6],[7]).
The qualitative descriptor (D3) for the provisioning ecosystem goods “Commercially exploited fish and shellfish” in Annex 1 of the MSFD reads: “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”.
2.1 MSFD Descriptor 3 criteria including methodological standards
In the Commission Decision 2010/477/EU ([8]) three criteria including methodological standards were described for MSFD Descriptor 3 (D3). The three criteria and associated indicators are:
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
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, which may reflect the extent of undesirable genetic effects of exploitation
Five main steps have been identified to assess Good Environmental Status (GES) for D3 ([9]):
1. Selection of commercially exploited (shell)fish populations relevant to the MSFD (sub)region, or MS-specific sub-division, being assessed with respect to D3;
2. Identification of stocks that can be assessed in relation to the primary assessment criteria for D3.1 and D3.2;
3. Determination of criteria to apply to stocks that cannot be assessed in relation to the primary assessment criteria, and identification of stocks that can be assessed according to the secondary criteria;
4. Interpretation of how to define GES for D3 with respect to combining individual stock assessments at the criteria level, and how to combine criteria level assessments at the descriptor level;
5. Assessment of current status in relation to GES.
2.1.1 Indicators from stock assessments
For the selection of what can be considered the commercially exploited (shell)fish in a particular (sub)region, the following key issues were identified: (1) Identification of the appropriate area; (2) Match of existing spatial units to that area; (3) Choice of data source; (4) Choice of time period; (5) Selection criteria. While each of these issues was seen to have some consequences for the selection of relevant populations, the overall assessment appeared fairly robust against a range of sensible choices.
For commercially exploited (shell)fish populations with assessments, primary indicators and MSY-based and/or precautionary reference levels are defined. As the assessed stocks do not always match the MS’s marine waters, issues pertaining to the selection of stocks considered representative for the MS’s waters arise. Another issue in the selection of assessed stocks to be examined under D3 concerned the quality of the assessments and, thus, the information they provide, i.e. (1) all indicators with reference levels, (2) not all reference levels, or (3) no reference levels. As the assessed stocks can be considered the best source of information, any decision on these aspects may have significant consequences for the GES assessment.
2.1.2 Indicators from monitoring programs
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. However it is noted that trends based methods do not provide specific definition of reference levels in relation to ‘good’ status, and can only provide an indication of change. None of the considered methods were evaluated, and therefore no recommendations are provided with regards to secondary indicators for criteria 3.1 and 3.2 or criterion 3.3. It was noted that the ‘mean maximum length across all species’ indicator proposed under criterion 3.3 is not appropriate as a stock condition metric and it is not advised for application under Descriptor 3.
An analysis comparing the outcomes of the GES assessments based on indicators with (from stock assessments) and without reference levels (from monitoring programs) showed some consistency, but also revealed that the GES assessment based on indicators with reference values is more strict than the one based on indicators without them. This is because with a relatively short time series the historic mean may still be far from where GES would actually be (and which should be represented by the MSY-based reference levels).
2.1.3 What is GES?
Three possible definitions of GES at the criterion level have been considered reflecting different levels of ambition ([10]):
· GES Interpretation 1: strict interpretation of the Commission Decision (8) 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.
The examples provided in the report of ICES work on D3 (9) confirmed that the interpretation of GES can have important consequences for the outcome of the GES assessment. A set of rules were used to show different ways that criteria may be combined (or not) for an overall assessment of current status in relation to GES. For the overall assessment of Descriptor 3, three approaches were considered in case studies: (1) no aggregation across criteria; (2) application of the one-out-all-out aggregation rule or “assessment by worst case”; or (3) application of weights for the different criteria.
GES for commercially exploited fish and shellfish will be achieved when stocks are sustainably exploited consistently with high long-term yields and have full reproductive capacity. To achieve GES it will also be necessary, in addition to sustainably exploited stocks at full reproductive capacity, for the age and size distribution of fish and shellfish populations to be representative of a healthy stock, assessed by reference to the proportion of older and larger fish in the population. GES is achieved for a particular stock only if criteria for all attributes are fulfilled ([11]). See Table 1.
Table 1 Risk categories for commercially exploited fish and shellfish (11).
2.1.4 Quality of GES assessment
Evaluation of the quality of the GES assessment should be provided. The quality of the assessment depends on the proportion of species/taxa that have information according to certain quality standards. A higher proportion of assessed stocks increases the quality of the GES assessment. Similarly, a higher proportion of species/taxa for which no information is available decreases the quality. The quality also increases with increasing length of the time-series of indicators without reference levels, to the extent that sufficiently long time-series would result in an assessment that could perform as well as one based on indicators with reference values. What can be considered “acceptable quality” remains unresolved but the different case studies explored a range of varying quality.
The current framework for GES assessment of Descriptor 3 can be consistently applied in all (sub)regions. However there are considerable differences between (sub)regions in terms of data availability that may compromise the quality of the assessment. For example a first assessment of the proportion of landings of all commercial species for which stock assessments are conducted shows that in the Baltic Sea this is more than 90% on an annual basis while in the central Mediterranean this is approximately 26% on an irregular basis.
Surveys that can provide data for the trend-based assessments of many additional species are conducted in each of the (sub)regions. There are, however, region- and survey-specific issues pertaining to suitability that need to be resolved. In general all research and/or monitoring initiatives that provide additional reference levels or improved indicators for more species will help in improving the quality and representativity of assessments.