Ocean warming drives a nearly 20% annual decline in fish biomass, research confirms

Phys.org

February 25, 2026

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A groundbreaking study reveals that chronic ocean warming is causing a significant decline in fish biomass, with an estimated 20% decrease each year. However, researchers have discovered that extreme marine heatwaves can temporarily offset this trend by increasing fish populations in specific regions, potentially masking the long-term negative effects of climate change on marine ecosystems. The research, conducted by the Museo Nacional de Ciencias Naturales (MNCN-CSIC) and the National University of Colombia, highlights the dual impact of rising ocean temperatures. While gradual warming leads to a steady reduction in fish biomass, sudden heatwaves can create localized population booms. This finding underscores the complexity of marine ecosystems and the need for a nuanced understanding of how they respond to environmental stressors. The study, published in *Nature Ecology & Evolution*, emphasizes the importance of distinguishing between long-term trends and short-term fluctuations. While extreme events like marine heatwaves may provide temporary relief to declining fish populations, the overall trajectory remains concerning. Chronic warming continues to pose a significant threat to marine biodiversity and food security, particularly in regions where fishing is a critical economic activity. Understanding these dynamics is crucial for developing effective conservation strategies and sustainable fisheries management. The findings also highlight the urgent need to address climate change to mitigate its long-term impacts on ocean ecosystems. As global temperatures rise, the balance of marine life will continue to be tested, with far-reaching consequences for both human communities and marine biodiversity. This research not only advances our knowledge of marine ecosystems but also underscores the importance of integrating both chronic and acute environmental stressors into ecological studies. By addressing the root causes of ocean warming and preparing for its unpredictable impacts, scientists and policymakers can work together to safeguard marine life for future generations.

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Originally published on Phys.org on 2/25/2026