Blue Crab
Overview
The blue crab (scientific name: Portunus trituberculatus) is a crustacean belonging to the family Portunidae of the order Decapoda, distributed along the coasts of East Asia, including Korea, China, and Japan. It is named 'blue crab' (꽃게) for the irregular flower-like patterns on its carapace, and in Korea, it is mainly caught in the West Sea (Yellow Sea) and South Sea. The blue crab has a mild flavor and tender flesh, making it versatile for various dishes such as soup, steamed dishes, stew, and seasoned salads. Particularly, autumn blue crabs are considered the best seasonal food as they are plump with meat. It is an indispensable marine resource on Korean dining tables and holds high economic value.
Main Content
Classification and Morphology
The blue crab belongs to the phylum Arthropoda, subphylum Crustacea, order Decapoda, and family Portunidae. Its carapace is nearly rhomboid in shape, characterized by long spines (frontal spines) extending sideways. The carapace color is brown with irregular white and blue patterns, resembling floral designs. Males have a narrow and long abdomen, while females have a broad and round abdomen. The chelipeds (claws) are large and strong, and among the four pairs of walking legs, the last pair is flattened like a paddle, adapted for swimming. Blue crabs undergo molting repeatedly as they grow, and immediately after molting, the shell is soft, earning them the name 'soft-shell crab' (연착게 or 물렁게).
Habitat and Ecology
Blue crabs inhabit sandy or muddy bottoms at depths of 10–50 m and are primarily nocturnal. They are omnivorous, feeding on small fish, shrimp, clams, crabs, and seaweed. The spawning season is from May to August, during which females carry hundreds of thousands of eggs attached to their abdomen. The eggs hatch after about 2–3 weeks, passing through larval (zoea) stages as they grow. The lifespan of a blue crab is about 2–3 years; one-year-olds are small, while those aged two years or older have higher commercial value. When water temperatures drop, they migrate to deeper waters to overwinter.
Fishing and Economy
In Korea, the west coast is the main fishing ground for blue crabs, with notable areas including Incheon's Yeonpyeong Island, Taean in South Chungcheong Province, Gunsan in North Jeolla Province, and Sinan in South Jeolla Province. Fishing methods primarily use gill nets and pots, with an annual catch of approximately 20,000–30,000 tons. Blue crab fishing has distinct seasonality, with peak seasons in spring (April–June) and autumn (September–November). Particularly, autumn blue crabs are so full of meat and flavorful that there is a saying, 'For autumn blue crabs, female crabs (기생게) are the best.' The price of blue crabs varies significantly depending on size, sex, and seasonality, trading at 20,000–50,000 won per kilogram in large supermarkets or online. Recently, increased imports of Chinese blue crabs have led to conflicts with domestic fishermen.
Cuisine and Nutrition
Blue crabs are used in a variety of dishes. Representative examples include blue crab stew (spicy stew), steamed blue crab, seasoned blue crab salad, marinated blue crab (soy sauce marinated crab or seasoned marinated crab), and blue crab soup. In particular, soy sauce marinated crab (간장게장) is called a 'rice thief' and is considered one of Korea's soul foods. Blue crabs are rich in protein and low in fat, making them suitable for diet foods. They are also abundant in minerals such as calcium, phosphorus, and iron, as well as vitamin B12 and zinc, aiding bone health and immune function. Chitosan found in crab shells is known for its antibacterial effects and cholesterol-lowering properties. However, blue crabs can cause allergies and have a cooling nature, so caution is needed depending on one's constitution.
Conservation and Management
For the sustainable use of blue crab resources, the government has established a closed season (June 21–August 20) and a minimum legal size (carapace width less than 8 cm) to regulate catches. Additionally, the capture of female blue crabs (기생게) is completely banned to protect spawning. Recently, rising water temperatures due to climate change have caused blue crab habitats to shift northward, and catch fluctuations have become more severe, necessitating long-term resource management plans.
Latest Trends
As of 2024–2025, blue crab catches have been on a declining trend compared to previous years due to climate change and overfishing. Particularly, the summer heatwave in 2024 raised water temperatures in the west coast by 2–3°C above average, affecting the growth and spawning of blue crabs and leading to a sharp drop in catches. Consequently, blue crab prices have risen by 20–30% compared to the previous year, burdening consumers. Meanwhile, advances in aquaculture technology have led to attempts at blue crab farming, but it has not yet reached the stage of commercial success. Additionally, imports of Chinese blue crabs continue to increase, intensifying price competition with domestic products, and cases of origin labeling violations have been uncovered, requiring consumer vigilance. The government is considering introducing a catch quota system from 2025 to restore blue crab resources and is in consultation with fishermen.
Related Topics
- [[Snow Crab]]
- [[King Crab]]
- [[Soy Sauce Marinated Crab]]
- [[West Coast Fisheries]]
- [[Crustaceans]]
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