Chionoecetes

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Chionoecetes
Chionoecetes bairdi.jpg
Chionoecetes bairdi
Daegu Yeongdeok crab.jpg
Chionoecetes opilio
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Brachyura
Family: Oregoniidae
Genus: Chionoecetes
Krøyer, 1838
Species

7 species (see text)

Chionoecetes is a genus of crabs that live in the northern Pacific and Atlantic Oceans. [1] [2]

Contents

Common names for crabs in this genus include "queen crab" (in Canada) and "spider crab". The generic name Chionoecetes means snow (χιών, chion) inhabitant (οἰκητης, oiketes); [3] opilio means shepherd, and C. opilio is the primary species referred to as snow crab. Marketing strategies, however, employ snow crab for any species in the genus Chionoecetes. The name "snow crab" refers to their being commonly found in cold northern oceans.

General

Snow crabs are caught as far north as the Arctic Ocean, from Newfoundland to Greenland and north of Norway in the Atlantic Ocean, and across the Pacific Ocean, including the Sea of Japan, the Bering Sea, the Gulf of Alaska, Norton Sound, and even as far south as California for Chionoecetes bairdi.

In 2019 the Norwegian Supreme Court ruled that the species is considered a sedentary species living on the seabed, and thus governed by the United Nations Law of the Sea. [4]

Species

Bagged frozen snow crab legs for sale in a supermarket Frozen Snow Crab Legs.jpg
Bagged frozen snow crab legs for sale in a supermarket

Seven extant species are currently recognised in the genus: [5]

Cookery

Crabs are prepared and eaten as a dish in many different ways all over the world. The legs are usually served in clusters and are steamed, boiled, or grilled. Snow crab can also be used as an ingredient in other dishes such as snow crab macaroni and cheese. [6]

Food web position and importance

Snow crabs are an important part of the ecosystem throughout the Pacific and Atlantic Oceans. They eat other invertebrates in the benthic shelf like crustaceans, bivalves, brittle stars, polychaetes, phytobenthos, foraminiferans, annelid worms, and mollusks. They are also fed on by halibut, cod, larger snow crabs, seals, squid, and Alaskan king crabs. Snow crabs are also highly sought after for the commercial fishing industry.

Life history stages and vulnerabilities

Juvenile snow crabs mature in cold-water pools on the ocean floor that are sustained by melting sea ice. If waters warm above the 2 °C maximum necessary for juvenile development, their normal nursery habitat will be reduced significantly. Adults are similarly unlikely to tolerate conditions of more than 5 °C. [7] With a gestation period of up to two years and an average spawn size of up to 100,000 eggs, their fecundity (i.e., fertility) is high, but recent trends have shown that these characteristics do not make them impervious to threats like a warming climate.

Population decline in the Bering Sea

2018 saw one of the warmest years coinciding with periods of the lowest sea ice extent on record in the Bering Sea. [8] The driver of this trend was the northeast Pacific marine heatwave, [9] which contributed to significant die-offs in a number of species. 2019 was yet another year of record-breaking temperatures, attributed to a weakened North Pacific High, which reduced evaporative cooling in the Northeast Pacific [9] and saw a steep declines in the number of juvenile crabs,. [10] [11]

In 2021, crabs of all ages declined, and habitat range shrank substantially. [10] 2022 saw the most drastic decline in Bering Sea snow crab populations, decreasing from 11.7 billion in 2018 to 1.9 billion in 2022 (a decline of approximately 84%). This decimation of the crustaceans’ population spurred the closing of the Alaska snow crab season for the first time in history, an industry worth approximately $160,000,000 annually.

Theories regarding decline

Though the cause is yet unknown, several theories behind this decimation have been put forward. Overfishing is likely the main driver, intertwined with the effects of climate change. [12] Increased water temperatures also increase snow crabs’ metabolism, so one theory is that their increased metabolic rate – combined with fewer resources due to a shrinking habitat – left them to either starve or consume each other. Predator range expansion is another possibility; as waters warm, predators that normally inhabit warmer southern waters (such as the Pacific cod) can travel further north in search of prey. A third theory is that a reduction in habitat area could increase the spread of disease like bitter crab syndrome. [10] All these theories tie back to an altogether warmer ocean and are supported by the impacts of low ice delineated in Thoman, et al. (2020). [8]

Bering Sea climatic impacts on snow crab

The Bering Sea southeastern shelf is composed of 3 biophysical domains: 1) a vertically well-mixed upper region (0–50m); 2) a middle region that is well-mixed in winter and stratified in summer (50–100m); and 3) an outer region with more gradual stratification (100–200m). [13] The Bering Sea shelf break (a zone where the shallower continental shelf drops off into the North Aleutians Basin) is the dominant driver of primary productivity in the Bering Sea – upwelling brings nutrients from the cold waters of the Aleutian basin to mix in shallow waters. This area is called home to many ecologically important species, including the snow crab.

To assess trends and impacts of the warming climate in the Bering Sea, a recent study created a regional model of both physical and biological elements of the Bering Sea using three global climate simulations from the Intergovernmental Panel on Climate Change Fourth Assessment. This model detected overall trends of warmer temperatures and a retreat of sea ice in the southeastern Bering Sea. Primary drivers of these higher water column temperatures include increasing air temperature and northward wind stress. [13] Warming trends on the outer Bering Sea shelf are concerning for a variety of reasons, one of which being that they may lead to decreased production of large crustacean zooplankton. On a broader spatial scale, sea surface temperatures (SSTs) that marked the start of summer in the North Pacific now come 11 days earlier and SSTs that marked the end of summer now come around 27 days later. Additionally, summers are on average 1.5 °C warmer and winters are on average 0.5 °C warmer. [9]

Historically, the Bering Sea continental shelf maintains between 40–100 % ice cover at its annual winter maximum. In 2018, the maximum sea ice cover was only 47 % of the 1979–2016 mean seasonal maximum extent. [8] Southeastward advection of melting sea ice contributes to the latitudinal salinity gradient of the Bering Sea, so when sea ice formation is reduced, the salinity gradient is altered. Though these don’t seem like significant changes, the inherent thermal conductivity of water (its ability to absorb heat) means that small changes like these are a big deal for marine organisms like the snow crab. It is yet unknown whether the Bering Sea snow crab population will recover, but scientists and policymakers will need to act quickly if improvement is to occur.

Related Research Articles

<span class="mw-page-title-main">Bering Sea</span> Sea of the northern Pacific Ocean off the coast of Alaska and Russia

The Bering Sea is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and the Americas. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves. The Bering Sea is named after Vitus Bering, a Danish navigator in Russian service, who, in 1728, was the first European to systematically explore it, sailing from the Pacific Ocean northward to the Arctic Ocean.

<span class="mw-page-title-main">Ringed seal</span> Species of carnivore

The ringed seal is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light gray rings, hence its common name. It is the most abundant and wide-ranging ice seal in the Northern Hemisphere, ranging throughout the Arctic Ocean, into the Bering Sea and Okhotsk Sea as far south as the northern coast of Japan in the Pacific and throughout the North Atlantic coasts of Greenland and Scandinavia as far south as Newfoundland, and including two freshwater subspecies in northern Europe. Ringed seals are one of the primary prey of polar bears and killer whales, and have long been a component of the diet of indigenous people of the Arctic.

<span class="mw-page-title-main">Alaska Current</span> Warm-water current flowing nortwards along the coast of British Columbia and the Alaska Panhandle

The Alaska Current is a southwestern shallow warm-water current alongside the west coast of the North American continent beginning at about 48-50°N. The Alaska Current produces large clockwise eddies at two sites: west of the Haida Gwaii and west of Sitka, Alaska.

<span class="mw-page-title-main">Spotted seal</span> Species of mammal

The spotted seal, also known as the larga seal or largha seal, is a member of the family Phocidae, and is considered a "true seal". It inhabits ice floes and waters of the north Pacific Ocean and adjacent seas. It is primarily found along the continental shelf of the Beaufort, Chukchi, Bering and Okhotsk Seas and south to the northern Yellow Sea and it migrates south as far as northern Huanghai and the western Sea of Japan. It is also found in Alaska from the southeastern Bristol Bay to Demarcation Point during the ice-free seasons of summer and autumn when spotted seals mate and have pups. Smaller numbers are found in the Beaufort Sea. It is sometimes mistaken for the harbor seal to which it is closely related and spotted seals and harbor seals often mingle together in areas where their habitats overlap.

<i>Deadliest Catch</i> American reality television series

Deadliest Catch is an American reality television series that premiered on the Discovery Channel on April 12, 2005. The show follows crab fishermen aboard fishing vessels in the Bering Sea during the Alaskan king crab and snow crab fishing seasons. The base of operations for the fishing fleet is the Aleutian Islands port of Dutch Harbor, Alaska. Produced for the Discovery Channel, the show's title is derived from the inherent high risk of injury or death associated with this line of work.

<span class="mw-page-title-main">Red king crab</span> Species of crustacean

The red king crab, also called Kamchatka crab or Alaskan king crab, is a species of king crab native to cold waters in the North Pacific Ocean and adjacent seas, but also introduced to the Barents Sea. It grows to a leg span of 1.8 m (5.9 ft), and is heavily targeted by fisheries.

<span class="mw-page-title-main">Zhemchug Canyon</span> Submarine canyon in the Bering Sea

Zhemchug Canyon is an underwater canyon located in the middle of the Bering Sea. It is the deepest submarine canyon in the world, and is also tied for the widest.

<i>Chionoecetes bairdi</i> Species of crab

Chionoecetes bairdi is a species of snow crab, alternatively known as bairdi crab and tanner crab. C. bairdi is closely related to Chionoecetes opilio, and it can be difficult to distinguish C. opilio from C. bairdi. Both species are found in the Bering Sea and are sold commercially under the name "snow crab." Tanner crabs have suffered from overfishing and as a result strict controls have been placed on tanner crab fisheries. It was named by Mary Jane Rathbun, a Smithsonian employee who became one of the leading authorities on crab taxonomy. She named the crab for Spencer Baird, her mentor, who in the 1880s as Secretary of the Smithsonian Institution and head of the United States Fish Commission, had given her her first position.

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<i>Chionoecetes opilio</i> Species of crab

Chionoecetes opilio, a species of snow crab, also known as opilio crab or opies, is a predominantly epifaunal crustacean native to shelf depths in the northwest Atlantic Ocean and north Pacific Ocean. It is a well-known commercial species of Chionoecetes, often caught with traps or by trawling. Seven species are in the genus Chionoecetes, all of which bear the name "snow crab". C. opilio is related to C. bairdi, commonly known as the tanner crab, and other crab species found in the cold, northern oceans.

<i>Oregonia bifurca</i> Species of crab

Oregonia bifurca, commonly known as the split-nose crab or the split-nose decorator crab, is a species of crabs belonging to the family Oregoniidae. It is a rare deep-water species that inhabits the tops of seamounts and guyots in the northeastern Pacific Ocean; from the Aleutian Islands, the Bering Sea, the Hawaiian–Emperor seamount chain, to the waters off British Columbia. It is closely related to the more common shallow-water species Oregonia gracilis, the graceful decorator crab.

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<i>Paralithodes brevipes</i> Species of king crab

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References

  1. ↑ L. S. Jadamec; W. E. Donaldson & P. Cullenberg (1999). Biological Field Techniques for Chionoecetes crabs (PDF). University of Alaska Sea Grant College Program.
  2. ↑ "ADW: Chionoecetes: CLASSIFICATION". animaldiversity.org. Retrieved 2021-11-08.
  3. ↑ Henrik Kröyer (1838). "Conspectus Crustaceorum Groenlandiae" [Survey of the crustaceans of Greenland]. Naturhistorisk Tidsskrift (in Latin). 2: 249–261.
  4. ↑ "Abide by the claw: Norway's Arctic snow crab ruling boosts claim to oil". Reuters. February 14, 2019.
  5. ↑ "Chionoecetes Krøyer, 1838". WoRMS. World Register of Marine Species. 2023. Retrieved 26 May 2023.
  6. ↑ "Freash Maryland Seafood Delivered Right To Your Door". Archived from the original on 2019-07-09. Retrieved 2019-01-04.
  7. ↑ Mason, Marc (2022-07-14). "Snow Crab: Everything You Need to Know". Surf's Up Magazine. Retrieved 2022-11-18.
  8. 1 2 3 Thoman, Richard L.; Bhatt, Uma S.; Bieniek, Peter A.; Brettschneider, Brian R.; Brubaker, Michael; Danielson, Seth L.; Labe, Zachary; Lader, Rick; Meier, Walter N.; Sheffield, Gay; Walsh, John E. (January 2020). "The Record Low Bering Sea Ice Extent in 2018: Context, Impacts, and an Assessment of the Role of Anthropogenic Climate Change". Bulletin of the American Meteorological Society. 101 (1): S53–S58. Bibcode:2020BAMS..101S..53T. doi: 10.1175/BAMS-D-19-0175.1 . S2CID   214295246.
  9. 1 2 3 Barkhordarian, Armineh; Nielsen, David Marcolino; Baehr, Johanna (2022-06-21). "Recent marine heatwaves in the North Pacific warming pool can be attributed to rising atmospheric levels of greenhouse gases". Communications Earth & Environment. 3 (1): 131. Bibcode:2022ComEE...3..131B. doi: 10.1038/s43247-022-00461-2 . S2CID   249873912.
  10. 1 2 3 "Billions gone: what's behind the disappearance of Alaska snow crabs?". The Guardian. 2022-10-20. Retrieved 2022-11-18.
  11. ↑ NOAA Fisheries (2022-05-17). "2022 Annual Bottom Trawl Survey of the Eastern Bering Sea". NOAA. Retrieved 2022-11-18.
  12. ↑ Roberts, Spencer (23 November 2022). "Where Have All the Snow Crabs Gone?". Nautilus. Retrieved 7 December 2022.
  13. 1 2 Hermann, Albert J.; Gibson, Georgina A.; Bond, Nicholas A.; Curchitser, Enrique N.; Hedstrom, Kate; Cheng, Wei; Wang, Muyin; Cokelet, Edward D.; Stabeno, Phyllis J.; Aydin, Kerim (December 2016). "Projected future biophysical states of the Bering Sea". Deep Sea Research Part II: Topical Studies in Oceanography. 134: 30–47. Bibcode:2016DSRII.134...30H. doi: 10.1016/j.dsr2.2015.11.001 .
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