Rising Ocean Temperatures Impacting 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 to February, negatively impacting the fisheries and aquaculture industries. This is the first time such a phenomenon has occurred since the Japan Meteorological Agency 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. The September-November period saw a 1.9 degree increase, while the December-February period experienced a 1.1 degree increase compared to the 30-year average from 1991 to 2020.
The record-breaking temperatures coincide with unusually high temperatures recorded in Japan and elsewhere last year. The agency reported the highest average temperatures for 2023 in the northern and northeastern regions since data collection began in 1946. Western Japan experienced temperatures on par with the highest recorded.
The high sea surface temperatures are expected to continue this year, with the agency forecasting air temperatures to be as high or higher than in 2023. This is attributed to global warming and a shift in the direction of the Black Current, a warm current flowing from south to north.
The Black Current typically changes direction eastward and flows away from Japan after approaching the Boso Peninsula. However, since spring 2023, it has continued to flow along the coast of the northeastern Tohoku region. This unusual shift has brought a variety of fish to the Tohoku region that have not been previously caught.
The high sea temperatures are also impacting 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.