Working Group for the Celtic Seas Ecoregion (WGCSE)

The Working Group for the Celtic Seas Ecoregion (WGCSE) performs stock assessments on demersal stocks in Rockall, West of Scotland, Irish Sea, West of Ireland, Western English Channel, Bristol Channel, Celtic Sea and Southwest of Ireland. In 2024, the Working Group provided updated fisheries data, reviews and advice for 10 Nephrops functional units and 21 fish stocks. These fish stocks include, three sole, four plaice, three haddock, three whiting, two cod, two megrim, one sea bass, one anglerfish, one pollack stock and one norway pout stock. For most of the stocks, advice was drafted in May and issued in June. Advice for Nephrops and Rockall megrim were issued in autumn so that they could take account of the in-year survey information. Cod in division 6a (cod.27.6a) which was previously assessed by WGCSE is addressed by WGNNSK as part of the North Sea Ecoregion, due to its close linkage with other North Sea cod stocks and fisheries (ICES, 2023a).

This year, analytical assessments using age-structured models were conducted for 14 fish stocks. For three stocks advice is based on the ‘rfb’ advice rule. Advice based on the application of the precautionary buffer was issued for two data-deficient stocks. Surplus-production models, without age or length structure, were used to assess lez.27.4a6a and lez.27.6b. Assessment and advice for pol.27-67 was conducted using a SPiCT assessment. In addition, one whiting stock (whg.27.7.a) for which advice is issued on a biennial basis, was presented and included in the report, although no new advice in issued in 2024.

Three stocks have gone through a benchmark procedure in the past year; anf.27.3a46 and sol.27.7a (ICES, 2024a), and had.27.6b (ICES, 2024b). The benchmark of anf.27.3a46 introduced a change from a category 3 to a category 1 assessment model (SS3), and incorporated new and revised survey indices and updated biological parameters. The benchmark of sol.27.7.a, also incorporated revised indices, catch estimates and a new commercial biomass index. Following benchmark, the 2023 advice for 2024 catch of sol.27.7.a was reassessed by the working group, and reissued in June 2024. The benchmark of had.27.6b introduced a change of the assessment method from a category 3 to category 1 (age-based assessment, SAM), incorporating revised survey data and updated biological parameters. Reference points were also revised.

Of the 19 fish stocks for which status could be assessed relative to MSY (or MSY proxy) reference points; eight were fished below F_MSY and were above MSY B_trigger, three were fished above F_MSY and were below MSY B_trigger, three stocks were fished above F_MSY and were above MSY B_trigger and five stocks were fished below F_MSY and were below MSY B_trigger. For two fish stocks for which advice was issued in 2024 reference points were unknown.

Underwater TV (UWTV) survey-based assessments were conducted for ten Nephrops functional units. Of the Nephrops stocks with UWTV assessments, all ten were fished below F_MSY. Five were above MSY B_trigger, and four were below MSY B_trigger. For Nephrops FU-16, B_trigger is not yet defined.