February 28, 2024 — 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. The work appears in Fish and Fisheries.
The researchers attributed the first period of weight loss to greater numbers of Japanese sardines, which increased competition with other species for food. During the 2010s, while the number of Japanese sardines 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.
Whether it’s sushi, takoyaki (traditional octopus pancake balls), or grilled mackerel, seafood is an iconic and important part of Japanese cuisine. Japan’s seafood self-sufficiency has, however, been gradually declining for several decades. Local fisheries face multiple challenges, from reduced sales and lower prices to labor shortages, changing consumer preferences, and soaring costs. But perhaps one of the biggest threats comes from global warming.
Japan’s eastern coast is bordered by the western North Pacific Ocean, a highly productive marine area. According to the U.N. Food and Agriculture Organization, in 2019, the western North Pacific accounted for almost a quarter of the global total of fish caught and sold. However, results of new research at the University of Tokyo show that during the 1980s and 2010s, fish weight in the region changed dramatically.