Climate change shrinking fish: Global warming increased competition for food in the 2010s, leading to decreased fish weight in important fishing area

28 Feb., 2024

AORI, The University of Tokyo

A view of Aomori Prefecture’s coastline, in northern Japan, where many species, including mackerel, sardine and cod, are fished. ©2024 Shi-ichi Ito

Fish weight in the western North Pacific Ocean dipped in the 2010s due to warmer water limiting food supplies, according to a new study at the University of Tokyo. Researchers analyzed the individual weight and overall biomass of 13 species of fish. In the 1980s and 2010s, the fish were lighter. They attributed the first period of weight loss to greater numbers of Japanese sardine, which increased competition with other species for food. During the 2010s, while the number of Japanese sardine and chub mackerel moderately increased, the effect of climate change warming the ocean appears to have resulted in more competition for food, as cooler, nutrient-dense water could not easily rise to the surface. These results have implications for fisheries and policymakers trying to manage ocean resources under future climate change scenarios.

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Climate change shrinking fish
https://www.u-tokyo.ac.jp/focus/en/press/z0508_00336.html