Long-term warming reduces fish biomass, but heatwaves shift it

Area of Science:

• Marine Biology
• Climate Change Science
• Fisheries Science

Background:

• Ocean warming, temperature variability, and marine heatwaves present significant threats to marine ecosystems.
• Quantifying the impacts of these climate-related stressors on fish populations is crucial for effective management.

Purpose of the Study:

• To quantify and isolate the individual effects of long-term ocean warming, interannual temperature variability, and marine heatwaves on fish biomass.
• To analyze the differential impacts on fish populations at the warm and cold edges of their geographic ranges.

Main Methods:

• Analysis of 702,037 biomass change estimates from 33,990 fish populations (1,566 species) between 1993 and 2021.
• Focus on major Northern Hemisphere basins to assess climate change impacts on marine species.

Main Results:

• Long-term ocean warming correlated with annual fish biomass declines up to 19.8%.
• Marine heatwaves and warmer years induced sharp biomass losses (up to 43.4%) at warm range edges and significant gains (up to 176%) at cold range edges.
• Identified 'winners and losers' in fish populations due to varying responses to short- and long-term warming.

Conclusions:

• Edge-dependent responses to warming ('winners and losers') must be considered in fisheries management to prevent overexploitation of temporary biomass increases.
• Future fisheries management strategies must account for projected fish biomass loss due to ongoing ocean warming.