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Study: heatwaves mask long-term fish biomass decline

newsMar 24, 2026152

A large-scale analysis of 33,990 fish populations over 25 years shows long term warming reduces fish biomass. Short term marine heatwaves produce local biomass surges that can temporarily offset or reverse that decline. Those spikes are temporary and regionally variable, and they can mask ongoing long term declines. This matters for fisheries management, because short term gains can mislead assessments and undermine conservation and harvest planning.

Key Highlights

Analysis of 33,990 fish populations over 25 years finds overall biomass declines
Short term marine heatwaves cause temporary local biomass surges that mask declines
Findings demand fisheries and conservation policies focus on long term trends