2026-10-06T12:52:42Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33980749 2026-09-30T12:28:06Z category_30425 category_30500 category_30506 portal_989 item_type_18 month_year_09_2026

Joint request from EU and UK on the impacts of different rebuilding harvest control rules (HCRs) for selected depleted stocks caught in mixed fisheries in the Celtic Sea and Eastern Channel ICES (11907875) Fisheries and aquaculture Celtic Seas (ICES Ecoregion) Greater North Sea (ICES Ecoregion) cod haddock whiting plaice Gadus morhua Merlangius merlangus Pleuronectes platessa rebuilding harvest control rules depleted stocks mixed fisheries HCR English Channel management strategy evaluation A shortcut management strategy evaluation (MSE) was conducted to explore potential rebuilding harvest control rules (HCRs) for five stocks: cod in divisions 7.e–k, haddock in divisions 7.b–k, whiting in divisions 7.b–c and 7.e–k, plaice in Division 7.d, and sole in Division 7.d. Simulations were conducted to explore the relative short- to medium-term impacts of applying HCRs which differ from the ICES advice rule (AR). A set of HCRs was evaluated wherein the advised fishing mortality decreased linearly below MSY Btrigger, with the same slope as the ICES AR, but when advised fishing mortality reached a specific value (Fmin), the advised fishing mortality was kept constant at this value up to spawning stock biomass (SSB) = 0. Different levels of minimum fishing mortality (Fmin) were tested. The HCRs were evaluated under two alternative stock productivity scenarios, low and medium, with the low-productivity scenario considered the most plausible assumption for the medium term.Results indicated that rebuilding prospects vary substantially between stocks and depend strongly on assumed future recruitment levels, with more precautionary HCRs generally improving recovery outcomes at the cost of reduced short-term fishing opportunities:Cod in divisions 7.e–k (western English Channel and southern Celtic Seas): Under the low-recruitment scenario, all HCRs are projected to increase SSB above Blim and MSY Btrigger in the medium term, although this outcome is highly dependent on the assumed stock–recruitment relationship. Biomass increases under all HCRs after an initial decline, while catches are expected to decrease in 2027–2028 before recovering.Haddock in divisions 7.b–k (southern Celtic Seas and English Channel): Continued low recruitment is projected to prevent stock rebuilding, with median SSB remaining below Blim under all HCRs throughout the simulation period. Catches are expected to decline to very low levels, and even the most precautionary HCRs only produce modest biomass increases.Whiting in divisions 7.b–c and 7.e–k (southern Celtic Seas and western English Channel): All HCRs result in moderate increases in SSB during the first decade, but none rebuild the stock above Blim. More precautionary HCRs provide the highest probability of stock improvement, while catches are projected to decrease initially and recover only moderately thereafter.Plaice in Division 7.d (eastern English Channel): SSB is projected to increase above Blim within 2–3 years under all HCRs, although higher Fmin values slow this increase. However, none of the HCRs are expected to rebuild the stock to MSY Btrigger.Sole in Division 7.d (eastern English Channel): All HCRs are projected to increase SSB above Blim in the medium term, with faster increases occurring under lower Fmin values.None of the HCRs rebuild the stock to MSY Btrigger, and the results reveal a trade-off between larger short-term catch reductions and improved long-term stock status and catches. Compared to a full MSE, shortcut MSEs have inherent limitations because of simplified assumptions regarding assessment model error as well as observation error. Uncertainty about these errors may have a substantial effect on the estimated probabilities, including the probability of SSB falling below Blim, but will generally have less effect on trends and median values. There are also uncertainties about modelling productivity realistically for these stocks, and this should ultimately be explored more thoroughly through a full reference set of operating models to find HCRs that are robust to these uncertainties. The results from these evaluations should not be considered predictions for the future. Rather, these analyses are an intermediate step between a short-term forecast (as done by ICES to provide annual catch advice) and full MSE. Results are sufficient to draw comparisons between alternative HCRs and can be used to guide decisions on interim measures until a full MSE can be conducted. 2026-09-30T00:00:00Z Text Report 10.17895/ices.advice.33980749.v1 https://figshare.com/articles/report/Joint_request_from_EU_and_UK_on_the_impacts_of_different_rebuilding_harvest_control_rules_HCRs_for_selected_depleted_stocks_caught_in_mixed_fisheries_in_the_Celtic_Sea_and_Eastern_Channel/33980749 CC BY 4.0