## Rising Ocean Temperatures Impacting Japan's Fisheries and Aquaculture
The surface ocean temperatures near the Japanese archipelago have reached record highs for three consecutive years, negatively impacting the fisheries and aquaculture industries. This is the first time such high temperatures have been recorded since the Japan Meteorological Agency (JMA) began tracking surface sea temperatures in 1982.
In 2023, the average ocean surface temperature in waters near Japan was 1 degree higher between June and August than normal. This trend continued through the rest of the year, with the September-November period experiencing a 1.9 degree increase and the December-February period seeing a 1.1 degree increase.
The record-breaking temperatures are attributed to global warming and a shift in the direction of the Black Current, a warm current flowing from south to north. This current typically changes 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. Miyagi Prefecture's fisheries technology center reported that fishermen at the Ishinomaki fish market caught species of fish that usually inhabit the waters off southern Japan, including giant trevally and spangled emperor. These species were previously believed to never migrate beyond the seas of the Kanto region.
The high sea temperatures 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 continued warming trend will likely have further impacts on Japan's fisheries and aquaculture industries, requiring adaptation and mitigation strategies to ensure the sustainability of these important sectors.