Scallops in Mutsu Bay Face Uncertain Future as Seawater Temperatures Rise

Scallops in Mutsu Bay, Aomori Prefecture, are facing an uncertain future due to rising seawater temperatures. The bay is the second largest scallop producing area in Japan, but recent years have seen a decline in scallop populations due to the warmer waters.

Hideto Takada, a scallop fisherman with over 50 years of experience, has witnessed the impact of rising temperatures firsthand. He estimates that 30% of his scallop fry died last year due to the record-high water temperatures. This year, the situation has improved slightly, but the threat remains.

According to the Aomori Prefectural Industrial Technology Research Center's Fisheries Institute, scallop fry growth slows when water temperatures exceed 23 degrees Celsius. They are at great risk of emaciation and death in waters above 26 degrees. In Mutsu Bay, water temperatures reached 25.3 degrees this year, significantly higher than the average of 22.9 degrees.

The rising temperatures have already had a significant impact on the scallop industry. The Aomori city fisheries cooperative association saw a 70% reduction in shipments this spring compared to standard levels. Fishermen are struggling to make a living, and some fear they may be forced out of business altogether.

The situation is not unique to Mutsu Bay. Rising seawater temperatures are affecting a range of regions and marine products. In Miyagi Prefecture, catches of ascidians and oysters are declining, leading to a growing sense of crisis among regional fishermen. The prefecture is exploring alternative options, such as pearl culturing, to adapt to the changing conditions.

The Copernicus Marine Environment Monitoring Service (CMEMS) has noted significant mercury surges in waters off the Sanriku area and other sites in Japan's northeastern Tohoku region. The warmer Kuroshio current from the south is exerting a stronger effect, leading to prolonged periods of extremely hot sea surface temperatures.

The situation highlights the urgent need for action to address climate change and its impact on marine ecosystems. Fishermen and researchers are working together to find solutions, but the future of scallops and other marine life in Japan remains uncertain.