Korean squid catches collapse as warming narrows their habitat
South Korean squid catches in 2023–2025 stayed below a tenth of their historical peak. A peer-reviewed observational study links the decline to long-term warming, marine heatwaves and the arrival of a warm-water predator. Ocean data accompany the catch series. The collapse concerns commercial fishing, rather than the biological disappearance of squid.
Science··Night
Catches fell below a tenth of their peak
South Korean catches of Japanese flying squid peaked at 225,122 tonnes in 1999. In 2023–2025, they stayed below 10% of that maximum, the threshold used to define commercial fishery collapse in a single peer-reviewed observational study. The East Sea, also known as the Sea of Japan, is the setting for the 1993–2025 analysis. The principal landing areas include Busan, Gangwon and Gyeongbuk; The September–December season supplies 72% of the yearly squid catch.[1]
Heatwaves overlap with the arrival of a predator
Squid’s reported thermal range extends from 13 to 23 °C. Japanese amberjack, a predator suited to warmer water, has a 20–30 °C range. The September heatwaves brought the average water temperature to 24.4 °C. Ocean reanalyses and catch records link squid decline to habitat degradation, acute heat stress and predator influx. A delayed association connects La Niña in early summer with autumn–winter temperature anomalies. Stronger winds and water movement toward the north feature in the proposed pathway, followed by warmer regional inflows.[1]
Landings also reflect effort and redistribution
Landings serve as a proxy for squid abundance, but fishing effort and redistribution can change them too. Catch-per-unit-effort comparisons were not continuous, and unmeasured shared drivers remain possible. After long-term trends were removed, some predator associations became less robust; the heatwave link to squid persisted. The projections draw on 10 climate models with an unchanged indirect predator effect. Their dynamics exclude adaptation in management, variations in recruitment and movement of the population between areas.[1]
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