SUMMARY | BIOLOGY | HABITAT
Snow crab – named for their sweet, delicate, snow-white meat – is one of Alaska’s signature crab fisheries. Although the Alaska snow crab fishery has had its ups and downs over the years, management has effectively responded to these fluctuations. Alaska snow crab is now above its target population level and managers boosted the harvest limit for 2011/2012 by 64 percent to nearly 90 million pounds.
In 2005, the derby-style fishery – where anyone could enter the fishery and the fishery was closed when the catch limit was reached – was replaced with an individual fishing quota (IFQ). Under the IFQ management system, individual fishermen are given a share of the harvest and can catch their share at any time during the fishing season. This has resulted in a safer and more efficient fishery, as fishermen can take weather and economic factors into account when deciding when to fish.
In Alaskan waters, female snow crabs can carry up to nearly 100,000 eggs, depending on their size. They hatch their larvae in the spring when there is plenty of food in the water column. Larvae, which look like tiny shrimp, live in the water and feed on plankton. The larvae molt and grow through three stages before becoming megalops, which look like crabs with long tails. Megalops seek out suitable habitat, settle, molt, and metamorphose into the first crab stage. From this point forward they look like miniature versions of the adult crabs, and will live on the bottom for the rest of their lives.
Snow crabs, like all crustaceans, can only grow by molting, because their hard shells (exoskeletons) prevent a gradual increase in size. When a crab is ready to molt, they absorb a lot of water and swell up inside their old shell until it pops open. Then they wriggle out of the old shell and absorb even more water to increase their size. Right after molting they are very soft and vulnerable to predators until their new shell hardens. Snow crabs molt several times a year for the first couple of years, but as they grow larger they molt less frequently. When they have reached sexual maturity, both females and males have a terminal molt, after which they never molt again. Females seldom grow larger than 3 inches in shell width while males can reach 6 inches. Scientists estimate that snow crabs may live for up to 20 years.
Snow crabs will eat almost anything they can catch and break open with their claws, including fish, shrimp, crabs, worms, clams, brittle stars, snails, algae, and sponges. They will also scavenge on anything dead they find. In turn, they are eaten by seals, sea otters, octopi, other crabs, and a wide variety of fish.
Snow crabs have a wide distribution. In Asia, they’re found in the Japan Sea and the Sea of Okhotsk. In the Atlantic, they’re found from Greenland south to Maine. In Alaska they live in the Bering, Beaufort, and Chukchi Seas, although they’re only harvested in the Bering Sea. They prefer soft sandy or muddy bottoms, typically in water less than 650 feet deep, where they can burrow if threatened by predators and where they can feed on the animals living in the sediment.