King crabs, also known as stone crabs, belong to a family of decapod crustaceans primarily inhabiting cold seas. Among the roughly 40 known species, Alaskan waters are home to three commercially harvested varieties: the red king crab, the blue king crab, and the golden king crab. These crabs are not only a culinary delicacy but also fascinating creatures with unique dietary habits and ecological roles.
King Crab Species in Alaska
Around 18 species of king crab are known to exist in Alaska waters. However, the most well-known Alaskan king crabs originate near the Alaskan coast. Some of the most popular King crabs are Alaskan king crabs, red king crabs, or Japanese crabs. The three primary species harvested commercially in Alaska are:
Red King Crab (Paralithodes camtschaticus): Also known as the Japanese crab or Kamchatka crab, the red king crab is the largest and most coveted of the commercially sold king crab species, making it the most expensive per unit weight. Live ones tend to have a more orange or burgundy hue, though some can even be a brownish-blue color. The name actually comes from the fact that they turn bright red when cooked. Red king crabs are the largest of the commercially harvested crabs and range in color from brownish to bluish red and are covered in sharp spines. They are mainly harvested in Bristol Bay, with some catch also coming from fisheries in Norton Sound.
Blue King Crab: Named for the touches of blue on their otherwise brown exoskeleton, the meat from the blue king crab is sometimes mistaken for red king crab meat because of its red and orange coloration. These crabs can be caught in the areas near St.
Golden King Crab (Lithodes aequispinus): Found from British Columbia to the Aleutian Islands and Japan, golden king crabs are smaller in size, averaging 5-8 lb, when compared to red and blue king crabs. They have a golden-colored shell and generally have the lowest percentage of meat "infill" inside the shell.
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Other notable king crab species include the Scarlet King Crab, Southern King Crab, Norway King Crab, Puget Sound King Crab, and Brown Box Crab.
Dietary Habits of King Crabs
King crabs are opportunistic carnivores, meaning they are not picky eaters and will consume a variety of food sources. Their diet changes as they grow, reflecting their changing needs and capabilities.
Baby King Crab: The diet of baby king crabs consists of phytoplankton and zooplankton, which are microscopic organisms drifting in the water column.
Juvenile King Crab: As they grow, juvenile king crabs consume diatoms, protozoa, hydroids, other crab, and other organisms that live on the ocean floor.
Adult King Crab: Adult king crabs have a diverse diet that includes worms, clams, mussels, snails, brittle stars, sea stars, sea urchins, sand dollars, barnacles, fish parts, and algae. Golden king crab eat a wide assortment of marine life including worms, clams, mussels, snails, brittle stars, sea stars, sea urchins, sand dollars, barnacles, crabs, other crustaceans, fish parts, sponges, and algae. Crabs have a strong sense of smell, helping them to find prey which they then grasp with their claws prior to consumption.
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King crabs use their strong claws to crush and tear apart their prey. They have two claws of different shapes; one is a large, heavy-duty claw used for crushing prey, while the other smaller claw is used for more delicate handling of food items.
Habitat and Distribution
King crabs are primarily found in cold waters. In general, king crabs can be found along the Alaskan coast, in the Bering Sea, and in the shallow waters surrounding the coast of Japan.
Depth and Distance from Shore: Golden king crabs live up to 1,600 feet deep in waters off Alaska and Russia. Red and blue king crabs instead like the sandy bottoms of shallower water, around 200 feet. The furthest point for king crab fishing is 200 miles from shore.
Specific Habitats: Mature crabs have a very set migration pattern. They come into shallow water to mate in late winter. Golden king crab tend to avoid open sand substrates and prefer steep-sided ocean bottoms. Juveniles are cryptic and rely on structure-forming sessile invertebrates growing on the sea floor, such as corals, sponges and sea-whips, to provide habitat.
Life Cycle and Reproduction
King crabs reach sexual maturity after about five years, and their reproduction cycle begins in the spring. In mid-spring, usually around May, mature female king crabs will migrate to warmer, shallower waters to ensure that they can safely spawn their eggs. They can spawn anywhere from 50,000 to 500,000 eggs at once.
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Male king crabs will join the females later in the season to fertilize the eggs, and females will then carry these eggs in their abdominal flaps for up to 12 months before they hatch. After hatching, king crab larvae resemble tiny shrimp. These larvae are called zoea, and unlike their adult counterparts, they are able to swim. They do not spend any time with the mother crab.
King crab larvae will molt up to five times in the first few months of their lives, and they then metamorphose into what is called a “glaucothoe.” This is a sort of in-between stage of growth for king crabs, which is similar to how many insects have a juvenile stage that essentially looks like a less-developed adult version of the creature.
These juvenile king crabs settle onto the ocean floor when they reach this stage of growth, and as they continue to grow, they will remain on the ocean floor and begin to move around and behave like adult king crabs.
Predators and Threats
The natural predators of king crabs include large fish like cod, halibut, and other similar species, as well as skates and sculpins. They are also in danger from octopuses and even other king crabs. The largest king crabs have very few natural predators due to their sheer size and the fact that they are only vulnerable right after molting.
Human harvesting of king crabs is another threat to wild populations. King crab populations are closely monitored to avoid overfishing. Because king crab population fluctuations are cyclical, fisheries maintain guidelines regarding how and when these crabs can be harvested to maximize their chances of reproducing and keeping population numbers high.
As an example, fisheries follow the “three S” rule: size, sex, and season. Only male crabs may be harvested, and they must be above a certain size threshold. Additionally, they are only allowed to be harvested outside of the mating and molting season.
Conservation and Management
The Alaska Department of Fish and Game’s research unit provides the biological and ecological information needed by managers to develop and implement sustainable management throughout Alaska.
The red king crab fishery is currently managed according to the “three S’s”-size, sex, and season. Only male crabs of a certain size may be harvested, and fishing is not allowed during mating and molting periods. These measures help ensure that crabs are able to reproduce and replace the ones that are harvested.
Fishermen must install escape panels and rings on their pots to prevent ghost fishing (when lost pots continue to capture and kill species) and to reduce bycatch. Every year, managers set the harvest limit for the next fishing season using the most recent estimates of crab abundance.
Managers allocate shares of the harvest among harvesters, processors, and coastal communities through the crab rationalization program, which was implemented in 2005 to address economic, safety, and environmental issues in the fishery. This program includes a community development quota, which protects community interests by allowing community groups a percentage of the harvest. They’re given the opportunity to purchase shares in the fishery before the shares are offered for sale outside the community.
Vessels carry vessel monitoring systems (satellite communications systems used to monitor fishing activities) and must report their landings electronically. Managers monitor catch in real time and are able to close the fishery when the harvest limit is reached. Observers are required on 20 percent of the vessels in the fishery.
The Alaskan King Crab Industry
Fishing is the leading economic activity in many parts of Alaska. Alaskan king crab fishing is carried out during the winter months in the waters off the coast of Alaska and the Aleutian Islands. The commercial harvest is performed during a very short season, and the catch is shipped worldwide. Large numbers of king crabs are also caught in Russian and international waters. Beyond commercial, there are also subsistence and personal-use fisheries for king crabs in Alaska.
Dutch Harbor, Alaska, is the main port of call for king crab fisherman. The majority of king crab fishing boats leave each season from Dutch Harbor and return after the season for processing and shipment.