The ICES Working Group on Mixed Fisheries Advice [WGMIXFISH-ADVICE] (Chair: Youen Vermard (FR)) met at ICES HQ, 22–26 May 2017 to produce mixed fisheries forecasts for the North Sea, the Celtic Sea and the Iberian waters.
Mixed fisheries advice highlights the potential implications of single stock (Total Al-lowable Catch and Effort) management on the catches of multiple stocks caught to-gether in mixed fisheries. It takes into account past fishing patterns and catchability of the different fleets and the TAC advice produced by the single stock advice groups for 2018 to provide quantitative forecast of over- and under- exploitation of the different stocks given mixed fishery interactions. All forecasts were based on the “Fcube” (Fleet and Fishery Forecasts) methodology with a range of potential management scenarios relevant for the specific regional fisheries.
For the North Sea (Term of Reference ‘a’) the species considered as part of the demersal mixed fisheries were cod, haddock, whiting, saithe, plaice, sole, and Nephrops norvegi-cus, as well as plaice 7.d and sole 7.d. The limiting TAC will be the TAC for haddock, whiting, and to a lesser extent Norway lobster in FU 6, which are the stocks for which the TACs are almost entirely taken when assuming that fishing fleets stop fishing once they have reached their first quota (scenario “Min”). Otherwise, substantial overshoot of TACs may occur (“Max” scenario). A “range” scenario is presented this year, in which the potential for TAC mismatch in 2018 are minimized within the FMSY range for demersal fish stocks where such a range is available. This scenario returns a fishing mortality by stock which, if used for setting single stock fishing opportunities for 2018, may reduce the gap between the most and the least restrictive TACs, thus reducing the potential for quota over- and undershoot. This “range” scenario suggests that the po-tential for mixed-fisheries mismatch would be lowered with a 2018 TAC in the lower part of the FMSY range for eastern Channel plaice and saithe, and in the upper part of the range for cod and North Sea plaice..
For the Celtic Sea (Term of Reference ‘b’) the species considered as part of the gadoid fisheries were cod, haddock and whiting. The most limiting stock (i.e. the stock where the first quota is reached for most fleets) in the Celtic Sea gadoid mixed fisheries in 2018 will be cod haddock. The least limiting stock (i.e. the stock which was the last quota to be fulfilled) will be whiting.
The meeting produced a Celtic Sea Mixed Fisheries Advice sheet and included out-comes of the mixed fisheries scenarios in the single species advice sheets (for those stocks considered) for consideration by the ACOM advice drafting group. The meeting also developed a mixed fisheries annex for the region and considered how Nephrops stocks could be included in future mixed fisheries forecasts. A “range” scenario is also presented this year for the Celtic Sea, in which the potential for TAC mismatch in 2018 are minimized within the FMSY range for demersal fish stocks where such a range is available. This scenario returns a fishing mortality by stock which, if used for setting single stock fishing opportunities for 2018, may reduce the gap between the most and the least restrictive TACs, thus reducing the potential for quota over- and undershoot. The ’range’ scenario suggests that TAC for cod is set slightly higher than the single stock advice, the haddock TAC is set between the FMSY estimate and the upper end of the range and the TAC for whiting set lower than the single stock advice, at the bottom of its range.