The largest species of crab found in the coastal waters of the United States is the Alaska king crab. The Alaska king crab inhabits the cold, deep waters off the coast of Alaska and can reach enormous sizes compared to other crab species. With a leg span of up to 6 feet, the Alaska king crab holds the title of largest crab in the US.
Characteristics of the Alaska King Crab
The Alaska king crab belongs to the scientific family Lithodidae, characterized by having a hard shell or carapace covering the back. The Alaska king crab has a reddish-brown, spiked shell and long, thick legs. Its two front legs are tipped with sharp claws, which the crab uses for defense and to pick apart food.
Some key identifying characteristics and stats on the Alaska king crab include:
| Scientific Name | Lithodes aequispinus |
| Other Common Names | Red king crab, giant crab, spider crab |
| Carapace Width | Up to 10 inches |
| Leg Span | Up to 6 feet |
| Weight | Up to 24 pounds |
| Lifespan | Up to 30 years |
| Habitat | Cold, deep waters of the Bering Sea and Gulf of Alaska |
With their huge size, Alaska king crabs are the giants of the crab world found in American waters. No other crab comes close to reaching the mammoth proportions of the Alaska king.
Range and Distribution
The Alaska king crab inhabits the frigid waters of the northern Pacific Ocean off the coast of Alaska. Its range extends from Norton Sound up through the Bering Sea and along the Aleutian Island chain.
Dense populations of Alaska king crab are found primarily in the deep waters of the Bering Sea, in areas such as the Pribilof Canyon and the waters surrounding the Pribilof Islands. These cold, rocky areas provide ideal habitat for the crabs to thrive.
Alaska king crabs prefer depths between 160 to 1,968 feet. They like areas with lots of crevices and rocks where they can hide from predators and hunt for food passing by in the currents. The crabs will migrate into shallower coastal waters during the winter breeding season.
Diet and Feeding Habits
The Alaska king crab is an opportunistic feeder, consuming a wide variety of available food. Their diverse diet includes:
- Mollusks such as clams, mussels, snails
- Worms such as polychaetes
- Echinoderms such as sea urchins and sand dollars
- Barnacles
- Small crustaceans
- Algae
- Decaying organic matter
The crab locates food with the sensory organs on its legs and claws. It then uses its strong claws to tear apart prey or scrape algae and detritus off rocks. The smaller mouthparts transfer the food to the larger crushing claws, which break down the food for the crab to consume.
Alaska king crabs are also aggressive predators. They will eat fish, octopus, other large crustaceans, and even smaller crabs they can catch with their vice-like claws.
Life Cycle and Reproduction
Alaska king crabs have a complex life cycle that involves several stages:
Egg: In early winter, female king crabs release up to 100,000 eggs. The bright orange eggs attach under the female’s abdomen.
Larvae: After the eggs hatch, the tiny larvae float as part of the zooplankton for about 3-4 months. During this stage they molt several times and increase in size.
Glaucothoe: The larvae then settle to the seafloor and enter the glaucothoe stage. They search for a suitable shell to inhabit.
Juvenile: Upon finding a shell, the crab enters the juvenile stage. At this point males and females look nearly identical. They molt and grow over the next 2-3 years.
Mature adult: Once sexually mature at 4-6 years, males and females exhibit size and shape differences. Mating occurs shortly after the female’s molt. The female only molts every 2 years, so mating opportunities are infrequent. Males continue molting annually to grow larger.
Alaska king crabs may live 20-30 years. Their large size and armored shell protect them from most predators, allowing them to grow quite old. Hunting by humans is their greatest threat.
Alaska King Crab Fishery
The Alaska king crab supports one of the most valuable commercial fisheries in Alaska. Red king crab and blue king crab are the two main species targeted. According to Alaska Department of Fish and Game statistics:
| Year | Pounds Harvested | Estimated Value |
|---|---|---|
| 2020 | 12.7 million | $73 million |
| 2019 | 9.5 million | $59 million |
| 2018 | 6.7 million | $52 million |
The Alaska king crab fishery is limited entry, meaning a permit is required. Crab pots with bait are used to harvest the crabs. Fishermen target mature male crabs to allow females to continue reproducing.
Strict management ensures the fishery is sustainable. Pots are limited per vessel and harvest is closed once quotas are met. Regulations also protect female and undersized crabs.
Threats and Conservation
The Alaska king crab population has experienced natural fluctuations over the decades, causing its conservation status to vary:
1960s-1970s: The population surged due to favorable environmental conditions.
1980s: The population declined rapidly as conditions changed. Fishery quotas were reduced.
2000s: Many areas were declared overfished and harvests closed to allow recovery.
2010s: Stocks rebounded close to 1980s levels in some areas, allowing limited fishing to resume.
While populations can fluctuate naturally, human impacts are also a threat. Effects of climate change, pollution, trawling, and sea otter predation may impact crab abundance. Careful monitoring and ongoing sustainable management practices will be key to conserving this iconic Alaskan species.
Other Giant Crab Species
While the Alaska king crab reigns as the largest crab in American waters, other giant crab species inhabit oceans worldwide:
| Species | Location | Size |
|---|---|---|
| Giant Japanese spider crab | Pacific coast of Japan | 12 ft. leg span |
| Giant Tasmanian crab | Southern coast of Australia | 12 lb., 15 in. across |
| Queen crab | Waters around New Zealand | 15 lb., 12 in. across |
While not as large as the giant Japanese spider crab, the Alaska king crab stands out as the most massive crab species in US waters. Even among giants, this crab secures its title as king.
Conclusion
With legs spanning up to 6 feet and weighing up to 24 pounds, the Alaska king crab is the undisputed largest species of crab inhabiting America’s coastal waters. This mammoth bottom dweller of the cold Alaskan seas exhibits impressive size and strength. Careful management of the fishery ensures populations of this iconic giant continue thriving for generations to come. The Alaska king crab remains one of nature’s true super-sized wonders.
