According to NIFS, this fall’s* catch of blue crab in the West Sea of Korea** is projected to increase by approximately 104-140% compared to the same season of the previous year (7,885 tons) and to 71-95% of the average 11,539 tons over the past five years.

*The spring fishing season: 4/1– 6/20, the fall fishing season: 8/21–11/30

**This fall’s blue crab catch in the West Sea (tons): (’15) 8,615 → (’18) 6,165 → (’21) 11,697 → (’23) 17,126 → (’24) 7,885 

This fall is projected to see an increase in the blue crab catch as the West Sea Bottom Cold Water –which acts in the concentration and dispersion of blue crab fishing grounds- expands to the coast and the south compared to the previous year, leading to the improved catch efficiency thanks to the concentrated fishing grounds. 

Additionally, the analysis points to the other contributors to the catch recovery; the increase in the transport volume of the Yellow Sea Warm Current (YSWC)* to the West Sea during the winter season (Jan.-Feb.), which has a high statistical correlation with the fall fishing season catch; and the increase in the size of crabs** during the spring fishing season. 

*YSWC Sv: (’20) 0.15 → (’21) 0.15 → (’22) 0.24 → (’23) 0.11 → (’24) 0.27

**Carapace width of blue crab in the spring fishing season (cm): (’20) 13.5 → (’21) 13.6 → (’22) 13.0 → (’23) 13.8 → (’24) 12.7 → (’25) 13.4 

Provided, however, that if HWT continues for a long time, fishing grounds can be dispersed, resulting in a decrease in catch. So NIFS plans to closely monitor and notify the continuing changes in water temperature. 

In addition, soft shell crabs are expected to appear in the fall fishing season as the decreased water temperature in the spring fishing season slowed the crab growth, leading to delayed molting and spawning. Whereas the crabs black inside is less likely to appear given the crab didn’t confirmed in the experimental fishing in June. 

In this spring fishing season, the catch* was 3,889 tons, which was a 56% decrease compared to 2024 (8,880 tons). NIFS says the reasons behind the decreased catch are this spring’s water temperature lower than previous year and the decrease in precipitation and larval distribution density of last year.

*This spring’s blue crab catch in the West Sea (tons): (’15) 5,146 → (’18) 2,744 → (’21) 3,440 → (’24) 8,880 → (’25) 3,889 

The West Sea Fisheries Research Institute of NIFS has predicted the catch amount by fishing season every year since 2004. Lately, it improve the prediction accuracy by utilizing artificial intelligence(AI) technology including machine learning*, XAI**, etc. 

*Machine learning refers to the technologies and algorithms that enable systems to identify patterns, make decisions, and improve themselves through experience and data. 

**XAI (eXplainable Artificial Intelligence) is a field of AI research focused on creating systems that can provide human-understandable explanations for their decisions and predictions.