The Japanese anchovy, sardine, and mackerel are crucial fish species in the studied region. Image Source: Phys.org
Beijing, February 29th, Science and Technology Daily (Reporter: Liu Xia) - Research conducted by scientists at the University of Tokyo in Japan reveals that fish inhabiting the western North Pacific have experienced a decline in weight during the 2010s due to limited food supply caused by warmer seawater. The latest findings shed light on how to manage ocean resources under future climate change scenarios. The relevant paper was published in the latest issue of the journal Fisheries and Aquatic Sciences.
According to data from the Food and Agriculture Organization of the United Nations, in 2019, fish from the western North Pacific accounted for nearly a quarter of the total global catch and sales of fish. Researchers investigated 17 populations of 13 fish species in the region, revealing that many fish species in the area experienced weight loss during the 1980s and 2010s.
The team analyzed long-term data from six populations of four fish species between 1978 and 2018, mid-term data from 17 populations of 13 fish species between 1995/1997 and 2018, and sea temperature data from 1982 to 2014 to understand whether changes in surface and subsurface ocean conditions affected fish.
The research team attributed the earlier decline in fish weight to an increase in the number of Japanese sardines, which intensified competition for food within fish populations and among species. However, in the 2010s, despite a slight increase in the numbers of Japanese sardines and mackerel, the rise in ocean temperatures led to larger zooplankton being replaced by smaller zooplankton and nutrient-poor gelatinous species (such as jellyfish). This reduction in nutritional supply resulted in a decrease in fish weight.
