Évaluation des stocks des sébastes (Sebastes fasciatus et Sebastes mentella) des unités 1 et 2 en 2024

Abstract

Status The spawning stock biomass (SSB) of S. mentella, estimated in 2024 at 1,737 kilotonnes (kt) (1,386-2,089 kt, 95% CI), places the stock in the healthy zone of the precautionary approach (PA). This level corresponds to 6 times the proposed Upper stock reference point (USR). The SSB of S. fasciatus, estimated in 2024 at 190 kt (9-371 kt, 95% CI), would be slightly above the proposed USR and in the healthy zone. However, S. fasciatus stock status is uncertain, owing to evidence suggesting the SSB may currently be overestimated, but the magnitude of this overestimation is not quantified. Trends Based on the Unit 1 survey, after an unprecedented increase from 2015 to 2019, the biomass of S. mentella larger than 22 cm, minimum regulatory size used to determine potential removals, substantially declined in the last five years, but was still among the highest values of the time series starting in 1984. The trend between 2018 and 2024 is unknown in Unit 2 due to the lack of reliable information. However, the biomasses of S. mentella larger than 22 cm estimated in 2018 and 2024 were above the value estimated in 2016. The 2024 value was the highest of the time series starting in 2000. The biomass of S. fasciatus larger than 22 cm in the Unit 1 survey was relatively stable and slightly above the average in the last three years. Based on the Unit 2 survey, the biomass of S. fasciatus larger than 22 cm declined from 2016 to 2018, and remained at a similar level in 2024, under the average of the time series. However, the trend between 2018 and 2024 is unknown in Unit 2 due to the lack of reliable information. No strong cohort of S. mentella and S. fasciatus has been observed since 2013. Ecosystem and Climate Change Considerations The increase in water temperature in the GSL and the Laurentian Channel would affect the Redfish growth. According to laboratory experiments, exposition to temperatures above 5 °C would result in a decrease in growth rates. Density dependence, observed with the high abundance of Redfish, would negatively affect feeding intensity, condition, and somatic growth of Redfish. Stock Advice According to various plausible natural mortality hypotheses, for the 2025-2026 fishing season, the potential removal median is 253 kt (range 80-291 kt) in Unit 1 and 115 kt (range 36-131 kt) in Unit 2 for S. mentella. For S. fasciatus, given the uncertainty in biomass estimates and species identification, and the assumptions underlying the method used, it is not possible to provide a reliable range of potential removals. Directing fishing towards greater depths may reduce catches of S. fasciatus in all fishing areas except the Laurentian Fan, where this species is found at greater depths. Given the low levels of recruitment and growth observed in recent years, even in the absence of fishing, Redfish biomass is expected to decrease in upcoming years due to natural mortality.