▲ A fisherman collects filefish that died from high water temperatures at a cage fish farm in front of Sanyang-eup, Tongyeong-si, Gyeongsangnam-do
"High water temperatures for farmed fish are just like pouring boiling water all over a person."
A 56-year-old fish farmer surnamed Kim, wiping sweat soaking his forehead and neck, made the remark on the morning of August 26 while met at a filefish cage fish farm in front of Sanyang-eup, Tongyeong-si, Gyeongsangnam-do.
Although the scorching heat should have subsided with Cheoseo, one of the 24 traditional solar terms marking the end of summer, the temperature around the cage fish farm soared to 34°C (93°F) on this day, and the surface layer (1 to 2 meters deep) thermometer read 28.8°C (84°F).
Standing on the cage fish farm under the blazing sun, Kim has been farming filefish there for about 10 years.
He has been repeatedly scooping up filefish that float to the water's surface and die with nets since two days ago.
Every time the landing net swept through the net, a fishy smell mixed with foul water odor rushed up, and red basins lined up on the deck piled up with dead fish.
Kim said that until before August 21, the water temperature was around 25.5°C (78°F), so he only ran the oxygen supply equipment occasionally and did not even install shading nets.
However, starting from August 21, the temperature of the surface layer rose by 2 to 3 degrees per day, instantly returning to high water temperatures.
"Data says they can endure up to 30 degrees, but that's when the water temperature rises gradually," he explained. "If it rises little by little by 0.5 degrees a day from 24 to 25 degrees, the fish can endure it, but if it shoots up by 2 to 3 degrees a day, they all die."
Raising his voice, he added, "A 1-degree rise in water temperature is similar to a 5-degree rise in air temperature. Suddenly rising by 2 to 3 degrees is truly a massive shock."
The amount of dead fish Kim has scooped up over the three days from August 24 to this day alone reaches about 1,700 kg, amounting to approximately 80,000 fish.
Estimating the unit selling price per fish at 4,000 to 5,000 won, Kim estimated the damage to reach 300 million to 400 million won.
Kim stopped his hands from scooping up dead filefish with the landing net.
"My heart hurts so much. It's not just hurting..." unable to finish his sentence, he lowered his head and stared down at the net for a long time.
This is not the first year Kim has suffered damage from high water temperatures.
Sighing, he said, "I suffered heavy losses from high water temperatures in 2024, but last year passed quietly with only a few fish dying naturally. That's why I couldn't even sign up for insurance this year, and now this happened."
He guessed that floating debris flowing into the sea in large amounts due to a landslide in a nearby mountain caused by recent record-breaking heavy rains may have also had a negative impact.
The burden of feed costs is also immense.
Feed costs, which usually cost about 30 million won per month, recently surged to 40 million to 50 million won due to reasons such as inflation.
With worries about red tides expected to hit after the high water temperatures overlapping, his expression was dark.
A high water temperature warning is currently in effect for all waters in the southern coast of Gyeongsangnam-do, including Tongyeong where Kim's fish farm is located.
The National Institute of Fisheries Science issues a high water temperature watch when seawater temperature reaches 28°C (82°F), and a high water temperature warning when the 28°C (82°F) temperature persists for three days or more.
This summer, more than 1.28 million farmed fish, including rockfish and black rockfish, have already died from high water temperatures in Gyeongsangnam-do waters alone.
Over the boiling sea, the furrowed brows of aquaculture fishermen are only deepening.
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