Évaluation du contingent nord du maquereau bleu (Scomber scombrus) en 2022

Abstract

Based on preliminary data, mackerel landings in Canadian waters totalled 4,505 t in 2021 (TAC = 4,000 t) and 74 t were landed in 2022 (TAC = 0 t). Mackerel landings in U.S. waters totalled 8,053 t in 2021 and 3,302 t in 2022, of which 20–80% is assumed to be from the northern contingent. The Spawning Stock Biomass (SSB) of the northern contingent of mackerel estimated with the revised assessment model was at its lowest values in 2021 and 2022 (40% and 42% of the Limit Reference Point; LRP), relative to 79% and 56% of the LRP in 2019 and 2020, respectively. Recent average recruitment (2012–2022) is at 27% of previous levels (1969–2011). There have been no signs of a substantial recruitment event since 2015. The probability of the SSB exiting the Critical Zone by 2025 ranges from 37.5% under a TAC of 0 t to 17.5% under a TAC of 8,000 t. The probability that the SSB in 2025 will be greater than in 2023 ranges from 78.5% (75–82%) under a TAC of 0 t to 32.5% (29–36%) under a TAC of 8,000 t. The probability of the SSB exiting the Critical Zone by 2025 under a baseline scenario assuming no Canadian fisheries removals is 38.5% (38–39%). The probability that the SSB in 2025 will be greater than in 2023 in the same scenario is 81% (78–84%). An investigation of predation pressure on mackerel by various predators in Canadian and U.S. waters suggests an overall increase in predation-induced mackerel mortality over time, with high interannual variability. The stock’s decline into the Critical Zone (2005–2011) was associated with high total landings and estimated fishing mortality above the reference level, with no further reduction in stock productivity and no known evidence of habitat degradation or loss. The northern contingent of mackerel has been in or near the Critical Zone since 2011. The available evidence indicates the stock rebuilding potential is currently limited by a truncated age structure, low recruitment, and high predation pressure.