Rising Sea Temperatures Impact Japan's Fisheries and Aquaculture
The surface ocean temperatures in waters near the Japanese archipelago reached record highs for the third consecutive year, from June 2022 to February 2023. This has had a negative impact on the fisheries and aquaculture industries.
The Japan Meteorological Agency (JMA) reported that the average ocean surface temperature in waters near Japan was 1 degree higher between June and August 2023 than normal. This is compared to the 30-year average of the same period from 1991 to 2020.
The higher temperatures were particularly noticeable on the eastern coastline of Honshu, the main island of Japan. This is a result of global warming and a shift in the direction of the Black Current.
The Black Current is a warm current that flows from south to north. It usually changes its direction to eastward and flows away from Japan after approaching the Boso Peninsula. However, since spring 2023, the Black Current has continued to flow along the coast of the northeastern Tohoku region.
This shift in the current is bringing a variety of fish to the Tohoku region that have not been previously caught. For example, fishermen at the Ishinomaki fish market have caught species of fish that usually inhabit the waters off southern Japan, including giant trevally and spangled emperor.
The high sea temperatures in recent years are also taking a toll on fisheries and aquaculture industries. Large hauls of yellowtail and blowfish have been reported in Hokkaido, while catches of cold water fish, such as salmon, have plunged in the sea off the Tohoku region. The higher water temperature is also affecting the growth of seaweed, which normally fares better in colder water.
The JMA expects the sea surface temperature to remain high this year, given the agency's forecast for this year's air temperature being as high or higher than in 2023. This could further impact the fisheries and aquaculture industries in Japan.