Snow-Tanner hybrid crab jumped to 41.7% of legal Bering Sea males after the heatwave

Hybrid crab, once rare in the eastern Bering Sea, now make up a large share of the crab snow crab fishermen are allowed to land. NOAA Fisheries posted the findings Oct. 19. Scientists at the Alaska Fisheries Science Center’s Kodiak Laboratory report in a new Proceedings of the National Academy of Sciences study that snow-Tanner hybrid abundance rose more than 13 times after the 2018–2019 marine heatwave. Commercial-size hybrid males went from less than 10% of harvestable males to 41.7% in 2025.

The researchers used dynamic structural equation models to look for cause and effect. They say warmer water and reduced sea ice did not directly help the hybrids, and adult snow and Tanner crab did not overlap more than before. Instead, billions fewer snow crab after the heatwave collapse most likely meant less competition and predation. The study attributes 76% of the hybrid and Tanner surge to those indirect effects. Tanner crab also reached their highest recorded abundance in 2025.

The catch for managers: male hybrids can be landed as snow crab in the winter fishery, but because they were so rare, the federal Bering Sea crab management plan never set separate harvest limits for them. NOAA says state managers raised the snow crab harvest limit in 2025, hoping fishermen would land more hybrids. Co-author Emily Ryznar said the 2026 survey found even more commercial-size hybrid males than in 2025. Lead author Erin Fedewa said this is the first time a rise in hybridization has been linked to a specific marine heatwave, and that crab management needs more room to adjust.

Photo: NOAA Fisheries / Leah Zacher (snow-Tanner hybrid crab from the 2026 eastern Bering Sea bottom trawl survey).

This is a The Gillnet news desk summary, not a reprint.

Source: NOAA Fisheries — Marine Heatwave Triggered a Hybrid Crab Surge in the Bering Sea (Alaska Fisheries Science Center, Oct. 19, 2026).