Report of the Workshop on Guidance on the Practical Methodology for delivering an MSFD GES Assessment on D3 for an MSFD Region/Subregion (WKGESFish)

WKGESFish met at ICES headquarters in Copenhagen, Denmark from the 18–19 March, 2016. The workshop explored methods on how to perform an integrated as-sessment of Descriptor 3 of the Marine Strategy Framework Directive (MSFD). WKGESFish explored how to: 

• Define the criteria or procedure to select the list of assessed commercially exploited fish and shellfish stocks (ToR1);
• Define the criteria for the assessment of [these] stocks in relation to GES for Descriptor 3 (ToR2);
• Conduct the assessment of Criteria 3.1, 3.2 and 3.3, to evaluate the GES status of selected stocks (ToR3).

The selection of species (ToR1) for regional assessments should be based on the re-gional list from the Data Collection Framework (DCF). For national assessments of D3 Member States should select the species and stocks which they are obliged to sample for stock variables within their national DCF-programmes.
Based on the outcomes of the back-to-back works WKIND3.3i, WKGESFish consid-ered Criteria 3.1 (level of pressure of fishing) and 3.2 (reproductive capacity of the stock) as operational criteria for the assessment of GES (ToR2). Criterion 3.3 was not included in the considerations of WKGESFish as WKIND3.3i did not identify any operational or appropriate indicators for the criterion.
WKGESFish explored the methods for integrating indicator assessment results within stocks across Criteria 3.1 and 3.2 as well as the aggregation of stocks within criteria (ToR3). The latter option was considered as preferable by most workshop participants, because the aggregation of stocks within criteria would avoid the problems associated with combining indicators with differing evidence base and levels of con-fidence (primary vs. secondary indicators), as well as the conceptual problem of combining pressure-related indicators (3.1) with state-related indicators (3.2).
WKGESFish also considered the aggregation of information on different stocks of the same species to species level, within a region. It was considered preferable to retain the focus on stocks rather than aggregating to species, as this promotes coherence with the CFP (which considers stocks) and avoid masking assessments when different stocks of a given species might have different GES status. 

To account for the aforementioned problems, WKGESFish recommends aggregating primary and secondary indicators within each criterion applying a two-stage reporting approach. Primary and secondary indicators within each criterion would be ag-gregated separately allowing full transparency on the evidence base while making the best use of available information.