Assessment of Scotian Shelf Snow Crab From 2023

Abstract

Snow Crab landings from the Scotian Shelf in 2023 were 972 t in north-eastern Nova Scotia (N-ENS); 7,342 t in south-eastern Nova Scotia (S-ENS); and 7 t in crab fishing area (CFA) 4X (season was ongoing at the time of assessment), representing a decrease of 0.3%, an increase of 0.3% and a decrease of 84.2%, respectively, relative to 2022. Total allowable catches (TACs) for 2023 were 979 t, 7,345 t, and 55 t in N-ENS, S-ENS, and 4X, respectively. Bycatch of non-target species is low (<<1% of total catch) in all Snow Crab fishing areas; however, as sampling targets for at-sea observer coverage have not been met in recent years, there is uncertainty in the representativity of the data. In N-ENS, the modelled biomass (pre-fishery) of Snow Crab in 2023 was 3.27 kt, a decline of 10.9% relative to 3.67 kt in 2022. In S-ENS, the modelled biomass (pre-fishery) was 37.91 kt, a decline of 10.6% relative to 42.42 kt in 2022. In 4X, the 2023–2024 season’s modelled biomass (pre-fishery) was 0.08 kt, a decline of 46.7% relative to 0.15 t in the 2022–2023 season. Egg and larval production is expected to be high in 2024 in S-ENS and 4X. Based on length frequency data, little to no recruitment is expected for the next 1–3 years in N-ENS. Continued recruitment is expected for the upcoming years in S-ENS. Low levels of recruitment are expected in 4X; high mortality of adolescent crab makes recruitment into the fishable component uncertain. In 2023, bottom temperatures from the Snow Crab survey have returned to the historical mean in all three CFAs; however, a general warming trend has been observed in the Snow Crab survey since the early 1990s. The amount of viable Snow Crab habitat has consistently declined in all three areas since 2010, and does not show any strong evidence of increase. In 2023, the N-ENS mean estimated fishable biomass was above the upper stock reference (USR), placing the stock in the healthy zone; however, there is considerable model uncertainty around both the estimate and the reference point. In 2023, the harvest rate was 30.17%, slightly above the harvest control rule of 10–30%. A more conservative harvest strategy may support the stock in bridging the expected gap in recruitment. In 2023, the S-ENS mean estimated fishable biomass was above the USR, placing it in the healthy zone; however, there is considerable model uncertainty around both the estimate and the reference point. Harvest rates derived from the fishery model were 19.7% in 2023, and have remained between 10–20% since 2020. The stock status in S-ENS suggests that the current harvest strategy has not been detrimental to the stock. In 2023, the 4X mean estimated fishable biomass was below the limit reference point (LRP), placing the stock in the critical zone. The area is in the southernmost extent of Snow Crab distribution in the North Atlantic and experienced an extended period of unfavorable conditions for Snow Crab in the region.