A prolonged heat wave and a spike in sea temperature has led to hundreds of thousands of fish dying in Pohang over a span of just six days, causing significant damage to fish farmers in the region. 

The eastern coastal city in North Gyeongsang Province revealed on Wednesday that 231-thousand fish bred at 24 land-based farms across the city, including starry flounder, halibut, and rockfish, have died since last Friday.

The temperature of sea water off Guryongpo in southern Pohang hovered around 28 degrees Celsius since Sunday, before falling slightly to 27-point-nine degrees as of Wednesday afternoon.

Sudden death of fish was also observed at fish farms in adjacent counties, including Uljin and Yeongdeok, where nearly 27-thousand-nine-hundred fish and nearly 20-thousand fish were found dead, respectively.