Trends of ocean temperature influencing snow crab catch along the Scotian Shelf

Abstract

The snow crab (Chionoecetes opilio) fishery has great economic importance for Nova Scotia, contributing $263 million to fisheries and more than one-fifth of Canadian snow crab revenues in 2021. Being a stenothermic species, snow crabs can only live within a narrow range of temperatures between −1 to 6 °C. The Scotian Shelf holds the southernmost populations of snow crab in the Atlantic and snow crab catch-per-unit-area (CPUA) in the Scotian Shelf. Trawl survey data from Ocean, because these cold-temperature requirements are a limiting factor for its distribution. This study investigates the relationship between bottom ocean temperature Fisheries and Oceans Canada from 2012 to 2021 were used. Through nonlinear modelling, CPUA (mt/km²) was regressed with respect to bottom ocean temperature along Northwest Atlantic Fisheries Organization divisions N-ENS, CFA 23, CFA 24, and CFA. The temperature-vs-CPUA relationship was unimodal for all studied years. The best-fit models explained a limited amount of variation, but CPUA consistently decreased to zero towards the highest recorded temperatures. Due to the ongoing global warming, bottom ocean temperatures across the Scotian Shelf will likely continue to increase, which thus might harm the Scotian Shelf snow crab fishery. In conclusion, this study underscores the potential impact of global warming on the economically significant snow crab fishery in the Scotian Shelf. The findings serve as a critical alert to the possible consequences of rising ocean temperatures, thereby contributing to our understanding and preparation for the future of marine ecosystems and industries.