Stock assessment of the European anchovy and European sprat in the Russian waters of the Black Sea in 2022–2023
The results of the stock assessments of the European anchovy and European sprat, exploited by the Russian Federation in the Black Sea exclusively or predominantly, are presented. Based on the results of production modeling in 2022, the biomass value of the “Azov Sea” anchovy stock unit was in the buffer zone, between the target and limit biological reference points (Btr=BMSY=123.3 thousand tons, Blim=61.6 thousand tons); the time of stock recovery to the target level is 4 years. The fishing mortality rate (annual fishing loss, F) in 2022 is estimated to be F2022=0.20, which is lower than the biological reference point (Ftr=0.23). The estimation based on the lampara net surveys is more favorable: spawning stock biomass (exploitable) SSB2022 exceeded Btr calculated using Ricker’s “stock–recruitment” relationship by 19 %. The Azov Sea stock of the European anchovy has been characterized as “showing the evidence for recovery under heavy exploitation; subjected to the environmental effects”. In the 2022/2023 fishing season, fishing operations on the Black Sea stock of the European anchovy were mostly absent due to the state-imposed limitation in the Northwestern Black Sea and the western waters along the Southern Coast of Crimea (SCC). The biomass of the “Black Sea” anchovy stock unit in 2022, based on the results of JABBA trend modeling in “catch-only” representation, has been estimated as B2022=22.5 thousand tons, which is 3 % lower than the target reference point Btr=BMSY=23.2 thousand tons. The ratio between the current fishing mortality and its biological reference point was F2022/FMSY=0.467, which is indicative of its low exploitation. The catch composition of the European sprat in 2022–2023 was characterized by the prevalence of the 2+ and 3+ age classes (71–87 % by abundance). Based on XSA, in 2022, the spawning stock biomass (exploitable biomass) SSB2022 was 67.2 thousand tons, the recruitment was 56 billion ind., and the fishing mortality was F2022=0.29. The spawning stock biomass was in the buffer zone between the limit and target biological reference points by the biomass (SSB2022/SSBtr=1.433, SSB2022/SSBtr=0.841), while the fishing mortality was considerably lower than its biological reference point (F/F0.1=0.479). In 2022, the current Black Sea stocks of anchovy and sprat were officially characterized as “declining, little exploited”, with the possibility for underestimation of their biomass.
| Main Authors: | , , , |
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| Format: | Journal Contribution biblioteca |
| Language: | Russian |
| Published: |
2023
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| Subjects: | Stock unit, Biomass, Biological reference points, Единица запаса, Биомасса, European sprat, European anchovy, Fishing mortality rate, Stock–recruitment relationship, Catch composition, Spawning stock biomass, Хамса, Шпрот (килька), ASFA_2015::S::Stock assessment, ASFA_2015::F::Fishing mortality, ASFA_2015::R::Recruitment, ASFA_2015::C::Clupeoid fisheries, ASFA_2015::A::Anchovy fisheries, ASFA_2015::P::Population structure, |
| Online Access: | http://hdl.handle.net/1834/42939 |
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