Lithodes aequispinus

Lithodes aequispinus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Family:	Lithodidae
Genus:	Lithodes
Species:	L. aequispinus
Binomial name
Lithodes aequispinus (Benedict J. E., 1895)

Lithodes aequispinus, the golden king crab, also known as the brown king crab, is a king crab species native to the north pacific. Golden king crab are primarily found in the Aleutian islands, as well as waters nearer to Alaska and British Colombia; their range also extends to the Russian far east and Japan, albeit with lesser population. Golden king crab are the smallest of the three commercially viable Alaskan king crab species with an average weight between 5 and 8 lbs(2.3 - 3.6kg); the other two species being the blue and red king crabs. Golden king crab were historically caught incidentally in red king crab fisheries, however the first commercial landing would take place in 1975; in 1981, the targeted pot fishing method, a hybrid fishing method specifically for golden king crab were developed.

Description

The golden king crab is a north pacific king crab, a decapod crustacean. They have 5 pairs of legs, the front pairs carry their claws. Golden king crabs get their name form the orange-brown to golden hue of their shell, which is mostly made of calcium. Like other king crabs, golden king crabs are large and have long spiny legs, however compared with blue and red king crabs, they are smaller by a great deal, with an average weight between 5 and 8 lbs, and notably thinner legs. The golden king crab also has a distinctive carapace, which typically has 5 - 9 spines on the mid-dorsal plate. Unrelated to their size, golden king crabs generally have the lowest meat-fill in proportion to their bodies compared with other Alaskan king crabs. They also have a fan shaped tail flap located on the rear and underside of their bodies; adult female crabs brood embryos underneath their tail-flaps.

Although Lithodes aequispinus may be referred to as either "golden king crab" or "brown king crab", The Code of Federal Regulations Title 21 Food and Drugs part 102 section 102.50 declared that the appropriate market name for Lithodes Aequispinus was “Brown king crabmeat”, however as of November 2017 this fact was overridden by section 774 of the consolidated appropriations act, 2017, which established the proper market name as “Golden king crabmeat”. Manufactures and sellers of products containing Lithodes Aequispinus were granted until January 1 2020 to make the appropriate change to product labels.

Distribution and habitat

The primary range of the golden king crab is around the Aleutian islands, as well as waters surrounding southern Alaska and British Columbia, however the range also includes the Russian far east and Japan to a lesser degree. Substantial Alaskan populations of golden king crab occur off of the Pribilof and Shumagin Islands, Shelikof Strait, Prince William Sound, and the lower Chatham Strait in Southeastern Alaska.

Golden king crabs typically inhabit deep waters ranging from 300 to 1000 meters in depth. They usually avoid open sand substrates, instead favoring complex sloping and rocky habitats, often relying on boulders or structure forming sessile invertebrates such as coral or sponges for habitat. Adult golden king crabs exhibit an annual deep and back migratory pattern during which they will travel to shallow waters in the late winter to molt and mate. This is followed by a return to deeper waters where they feed and exist for most of the year. Golden king crabs often occupy deeper waters than red king crabs; within their geographical range they are the most abundant species of crab.

Reproduction and life cycle

Golden king crabs exhibit 20 month asynchronous reproductive cycles during which female crabs will typically brood 10,000 to 30,000 eggs underneath their fan shaped tail flaps for roughly a year. Golden king crab have the largest eggs of the three commercially viable king crab species. Offspring emerge as swimming larvae, however, are weak and susceptible to underwater currents. Throughout their transformation into adulthood, golden king crabs will undergo several physical transformations via molting. Offspring eventually settle at the bottom of the ocean in waters with a usual minimum depth of 300 feet.

Golden king crabs are typically classified as juvenile in their first few years. After reaching sexual maturity at around 4 to 5 years of age, they are classified as adults. Golden king crabs molt throughout their entire life, however juveniles do so more frequently than adults. Due to reproductive necessity, females molt more often then their male counterparts who can keep their shells for one to two years at a time.

Throughout their lives, golden king crabs exhibit an annual offshore “deep and back” migrational pattern which involves male and female crabs arriving in shallow water in late winter and early spring in order to molt their shells and mate. When embryos hatch in late spring, they then leave into deeper waters for feeding, wherein they are not typically found with crabs of the opposite sex nor with red or blue king crabs.

Golden king crabs consume a wide variety of species including worms, clams, mussels, snails, sea stars, urchins, sand dollars, barnacles, algae, sponges, and even other crabs and crustaceans. Many crabs have a strong sense of smell, the golden king crab uses this to locate food. Golden king crabs are also preyed on by various fishes such as pacific cod, halibut and yellowfin sole, as well as sea otters. Nemertean worms have also been found to consume the embryos of golden king crabs.

Fisheries

Due to their small size, golden king crab is not as popular as blue or red king crab, however they are widely fished throughout Alaska, particularly in the Aleutian islands. In comparison with other commercially viable king crabs, golden king crabs are noted as being similar in flavor, but perhaps milder and sweeter.

In order to protect the golden king crab stock in Alaska, several regulations have been established. Crab fishermen may only catch and harvest male king crabs of a legal size, that being 7 cm laterally across the carapace. Fishing also must not coincide with mating and molting periods.

After the North Pacific Council approved stock assessments of golden king crab, state managers were allowed the authority to increased crab fishing quotas by the Alaska Board of Fish. As of 2015, in coordination with the industry, the state has conducted numerous surveys of golden king crab stock. As of August 2018, quotas for Golden King Crab fishing rose for the first time in 20 years. This allowed the taking of 3.9 million pounds of golden king crab east of Adak island, and 2.5 million pounds west of Adak: respective increases of 18 percent and 11 percent. In the following season, as of August 2019, quotas for golden king crab harvest were again increased, allowing 4.3 million pounds to be taken east of Atka island, and 2.9 million west of Atka. The raised quota represented respective increases of 12 and 15 percent since the previous season. The 2019 golden king crab season is the second for which the government’s new stock assessment model was used. The new stock assessment model determines seasonal crab stock more thoroughly than previous methods and is unique to golden king crab.