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Blue king crab

Paralithodes platypus
Paralithodes platypus (museum).jpg
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Lithodidae
Genus: Paralithodes
Species: P. platypus
Binomial name
Paralithodes platypus
(Brandt, 1850)

Paralithodes platypus, the blue king crab, is a species of king crab which lives near St. Matthew Island, the Pribilof Islands, and the Diomede Islands, Alaska, with further populations along the coasts of Japan and Russia. Blue king crabs from the Pribilof Islands are the largest of all the king crabs, sometimes exceeding 18 pounds (8.2 kg) in weight.

Commercial blue king crab harvest around the eastern Bering Sea began in the mid-1960s and peaked in 1981 with a catch of 13,228,000 pounds (6,000 t). The Pribilof Island harvest by the United States peaked in 1980 at 10,935,000 lb (4,960 t) and was closed in 1988 due to population decline, then again in 1999 after being opened for three years. The St. Matthew fishery peaked in 1983 with 9,453,500 lb (4,288.0 t) but experienced a similar decline and was closed in 1999. It was opened in 2009, and was featured on the television show Deadliest Catch. The St. Matthew stock is rebuilding but the fishery remains closed, while the Pribilof stock has not drastically improved. Diomede blue king crabs have never been harvested commercially, but support a subsistence fishery for the Native Village of Diomede, Alaska, population 170.

Colder water slows the rate of crab growth and crabs at northern latitudes are often smaller than more southern crabs. Commercial harvest of blue king crabs at the Pribilof Islands is limited to males with a carapace width (CW) over 6.5 inches (170 mm) and St. Matthew Island is limited to crabs with CW greater than 5.5 in (140 mm), corresponding to crabs over 4.7 in (120 mm) carapace length (CL). Diomede blue king crabs are similar in size to St. Matthew Island crabs.

Blue king crabs can be found in the Bering Sea in relatively small abundances compared to red king crabs. The main populations near Alaska are found near the Diomede Islands, Point Hope, St. Matthew Island, and the Pribilof Islands. Additionally, populations exist in the Norton Sound all the way to the St. Lawrence Islands. There are smaller populations located off the eastern coast of Asia, near northern Japan and Siberia. Blue king crabs have a more northerly distribution compared to red king crabs, which is due to the colder waters of the northern Bering Sea being suitable for blue king crabs to survive. The unique population locations of the blue king crab are a result from glacial interactions with the water temperature of the Bering Sea. A period of increased temperature limited the spread of cold-water species, pushing the species further northward into the depths of the Bering Sea. Not only did blue king crabs retreat to the northern stretches of the Bering Sea, but they also had a possible population shrinkage due to glacial epochs.


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Wikipedia

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