Rising Sea Temperatures Impact Fishing in Japan
The first half of 2023 saw record-high sea surface temperatures around the Japanese archipelago, with the Pacific Ocean off Hokkaido experiencing a particularly significant warming. This phenomenon, attributed to an abnormal flow of the Kuroshio Current, has already begun to impact fishing activities.
Drift-net fishing boats set off from Habomai in Nemuro, Hokkaido, on April 3, marking the start of the salmon and trout fishing season. This year, the season began a week earlier than usual due to rising sea temperatures, making it difficult to catch salmon and trout at the end of the season.
Experts believe that the northward movement of the Kuroshio Current is preventing the southward movement of the cold Oyashio Current, leading to more frequent and intense ocean heat waves. These heat waves are believed to be responsible for changes in the undersea environment, triggering explosive growth of toxic phytoplankton and causing red tides.
Hiroshi Kuroda, a group leader of marine physics at the Japan Fisheries Research and Education Agency, noted that the likelihood of ocean heat waves has increased fourfold in the 2020s compared to the early 1990s. This trend is expected to continue, posing significant challenges for the fishing industry and marine ecosystems in Japan.