New study explores the future of snow crab and cod in warming waters of the Grand Banks

Tuesday, November 26, 2024

A new study examining the effects of climate change on three key Grand Banks fish species projects that warmer waters could lead to biomass declines for snow crab and yellowtail flounder, and biomass gains for Atlantic cod.

Using species distribution models to understand habitat changes due to warming waters on the Grand Banks of Newfoundland, eight researchers at the Fisheries and Marine Institute of Memorial University, Fisheries and Oceans Canada and Dalhousie University assessed long-term projections to the year 2100.

Globally, climate change is shifting the distributions of marine organisms, as species follow their preferred temperature range – affecting ecosystems and posing adaptation challenges for fisheries.

Research findings

Species distribution models showed biomass losses were most pronounced for snow crab, specifically at the north and south ends of the Grand Banks.

“By the end of the century, snow crab biomass is expected to decline by about 60 per cent on the Grand Banks, where most of the quota is allocated,” said Raquel Ruiz-Diaz, PhD candidate in fisheries science at the Marine Institute.

Ms. Ruiz-Diaz is lead author of the report, “Climate models drive variation in projections of species distribution on the Grand Banks of Newfoundland,” published in PLOS Climate.

Report co-authors also include Drs. Tyler Eddy, Jonathan Fisher and Sherrylynn Rowe from the Marine Institute’s Centre for Fisheries Ecosystems Research (CFER).

“Our findings highlight how climate change will affect the key fisheries resources that are the livelihoods for many and the need for fisheries management that can adapt to ensure sustainable fisheries for future generations,” said Dr. Eddy, research scientist with CFER.

Temperature preferences

Snow crab prefer cold-water environments below five degrees Celsius commonly found in subpolar and Arctic regions, while yellowtail flounder thrive in low sea bottom temperatures ranging from one to six degrees Celsius.

Yellowtail flounder distribution is centered on the Grand Banks’ southeast shoal, which is considered a nursery and an area where higher warming levels are expected.

Atlantic cod, which tolerates higher water temperatures than the other two species, is expected see a biomass gains to occur mostly in the southern Grand Banks.

Species survey data

Using more than 50 years of Fisheries and Oceans Canada survey data for snow crab, yellowtail flounder and Atlantic cod and the ocean temperatures where they were observed, researchers developed temperature preference relationships for each species.

Future climate change projections of ocean warming on the Grand Banks under low- and high-emissions scenarios were compared to the species’ temperature relationships to see how their preferred temperature ranges are expected to change from present day to the end of the century.