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EXECUTIVE SUMMARY

The benchmark session for Black Sea anchovy (Engraulis encrasicolus ponticus) and sprat (Sprattus sprattus) of the Subregional Group on Stock Assessment for the Black Sea (SGSABS) was held in Batumi, Georgia, in hybrid modality, on 1–5 July 2023. The meeting was attended by 18 attendees from Bulgaria, Georgia, Romania, Türkiye and Ukraine, including from the Secretariat of the GFCM, the BlackSeaforFish (BS4F) Project and the European Comission. The meeting aimed at carrying out the benchmark sessions for Black sea anchovy and sprat, which were launched in 2023 and 2018, respectively. These benchmark sessions for anchovy and sprat were based on updated and revised input data compiled up to the refence year 2023. Two different stock assessment models, the Surplus Production Model SPiCT (1960–2023) and the age-structured FLSAM (2009–2023) were proposed by the Group for both stocks. For anchovy, issues related to ageing prevented running FLSAM, so the stock assessment was conducted only with SPiCT. For sprat, both SPiCT and FLSAM stock assessments were carried out, providing comparable results. For anchovy, the Group highlighted the need to retrieve adequate age-length key (ALK) data covering different periods, identifying and applying the contributions of different populations in available length–frequency data and harmonizing survey data in order to face a new benchmark session. As a result, the stock assessment for anchovy in geographical subarea (GSA 29) was validated, providing qualitative advice, as possibly overexploited, with the recommendation of "Do not increase fishing mortality". For sprat, the Group finalized the benchmark, providing quantitative advice from the age-structured FLSAM model. The Group decided to benchmark the assessment based on FLSAM, providing quantitative advice that the sprat stock is sustainably exploited, with the advice of "Do not increase fishing mortality". An extended benchmark report by stock has been prepared for each stock.