Snow crab
| Snow crab | ||||||||||||
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Snow crab ( Chionoecetes opilio ) |
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| Scientific name | ||||||||||||
| Chionoecetes opilio | ||||||||||||
| ( Fabricius , 1788) |
The snow crab ( Chionoecetes opilio ), even snow crab , Nordic Arctic shrimp or Snowcrab called, is a predominantly on the unconsolidated sediments of the continental shelf live cancer , predominantly in the north-western Atlantic and North Pacific Ocean occurs.
In the food trade it is one of the crustaceans .
features
The top of the snow crab is reddish to brownish, the underside is whitish-yellow. The carapace , covered with flat, rasp- like tubercles , is hard due to calcium deposits and almost as wide as it is long. The rostrum is short and wide, with two flat-pointed "horns" separated by a gap. The carapace width (CW) of males reaches up to 150 mm, that of females up to 90 mm. Male animals can weigh up to 1.35 kg and a leg span of up to 90 cm, while females weigh just under 0.5 kg and have a leg span of up to 38 cm. In addition to size and weight, the sexes have larger claws and a triangular-shaped abdomen of the males, while the females have smaller claws and the abdomen has a more rounded shape. In both sexes, the abdomen consists of seven different segments.
The scissor bones are somewhat flattened laterally, their inner, outer and lower edges with sharp granules. The scissors hand and carpus are not flattened, their upper, lower and outer sides are studded with sharp spines. The fingers are longer than the scissors hand, very slender and serrated along their entire length. There is a wide tooth near the base of the movable finger. The next three legs are flattened on the sides, with a long merus and significantly longer than the scissors . The front two are about the same length, the third a little shorter and the last very small. The sides of the feet are shiny white.
The species Chionoecetes bairdi , which occurs in the Pacific distribution area of the snow crab , differs from the snow crab in that the carapace is wider than it is long in Chionoecetes bairdi .
distribution
The original range of the snow crab includes the western Atlantic from Greenland via Newfoundland to the Gulf of Maine and the North Pacific from Arctic Alaska to the west to northern Siberia and south through the Bering Strait to the Aleutian Islands , Kamchatka Okhotsk , Japan and Korea .
The first specimens of the snow crab were found in the Barents Sea in 1996, and in Norway in 2003 . Studies show that juvenile and adult animals of both sexes as well as egg-bearing females occur in the Norwegian and Russian exclusive economic zones , so that the species can be regarded as established in the Barents Sea.
Habitat and way of life
The snow crab is a benthic inhabitant of the shelf regions and the upper continental slopes . It lives on sandy and muddy soils at depths of 20 to 1200 m, Atlantic stocks most frequently at depths of 70 to 280 m. As a subarctic inhabitant of cold water, the snow crab mainly occurs at temperatures from 0 ° C to 5 ° C, in the Saint Lawrence Gulf from −1 ° C to 2 ° C.
Males and females spend most of the year separately, males on muddy ground in deeper water, females on sandy-gravelly or stony ground in shallower water. Snow crabs are highly reproductive . Most females reach sexual maturity with a carapace width of 40 to 75 mm (at the age of four to six years or between eight and 10 moults) and each year, depending on their size, carry 12,000 to 160,000 eggs under the abdomen. The gestation time of the eggs depends on the water temperature, the larvae hatch after a year or two.
Snow crab feed on benthic invertebrates living as crustaceans, clams , brittle stars , Vielborstern (z. B. sabellidae ) and fishing. Young specimens take phytobenthos and foraminifera . According to an investigation on snow crabs from the northeastern Newfoundland shelf, shrimp, e.g. B. from the genus Pandalus , more often prey for females, while fish (mainly capelin ) are more prey for males. Even cannibalism on smaller snow crab happens more frequently by females.
Taxonomy and systematics
The snow crab was originally assigned as Cancer opilio to the genus Cancer by Otto Fabricius and transferred by Krøyer in 1838 as the only species and thus as a type species in the genus Chionoecetes . In 1924, Mary J. Rathbun described the subspecies Chionoecetes opilio elongatus , which is now regarded as a separate species, Chionoecetes elongatus .
Catch and use
The commercial catch of snow crab began in Canada mid-1960s. Originally bycatch in trawl fishing (analogous to crab fishing ), snow crabs are now caught in trap- like traps that are brought out by ships and later collected again. The animals are always looking for hiding places on the sea floor and therefore like to climb into traps. Only male animals with a carapace of more than 9.5 cm may be collected for food. In 2007, 90,000 tons of snow crabs were landed from Canada's Atlantic fishing areas.
When the crab meat is extracted, large quantities of shell remain after the crab peel, which is usually disposed of directly in the sea as fishing waste. But you can for the production of chitin and carotenoids recycled are.
Individual evidence
- ↑ a b c d e f g h i j k FAO Fisheries and Aquaculture Department: Species Fact Sheets Chionoecetes opilio (O. Frabricius, 1788)
- ↑ a b c d Snow crab ( Chionoecetes opilio ) in the Marine Species Identification Portal
- ↑ a b c Snow Crab at Fisheries and Oceans Canada (DFO)
- ↑ Chionoecetes opilio (O. Fabricius, 1788) - Snow crab ( Memento of the original from December 25, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. at The European Network on Invasive Alien Species (NOBANIS)
- ^ MJ Tremblay: Snow Crab (Chionoecetes opilio) Distribution Limits and Abundance Trends on the Scotian Shelf. In: Journal of Northwest Atlantic Fishery Science. 21, 1997, pp. 7-22. (online) ( Memento of the original from August 19, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ A b Hubert J. Squires, Earl G. Dawe: Stomach contents of snow crab (Chionoecetes opilio, Decapoda, Brachyura) from the Northeast Newfoundland Shelf. In: Journal of Northwest Atlantic Fishery. Vol. 32, 2003, pp. 27-38. (online) ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ P. Davie: Cancer opilio O. Fabricius, 2014 at World Register of Marine Species (WorMS) (online)
- ↑ P. Davie: Chionoecetes Krøyer, 2014 at World Register of Marine Species (WorMS) (online)
- ^ Peter KL Ng, Danièle Guinot, Peter JF Davie: Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world . In: Raffles Bulletin of Zoology . tape 17 , 2008, p. 1–286 ( online [PDF]).
- ↑ Alaska Fish: The Fishing Methods in Alaska. (online) ( Memento of the original from May 31, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ RJ Miller: Density of the commercial spider crab, Chionoecetes opilio, and calibration of effective area fished per trap using bottom photography. In: Journal of the Fisheries Board of Canada. 32, No. 6, 1975, pp. 761-768, doi: 10.1139 / f75-099 .
- ↑ Fereidoon Shahidi, Jozef Synowiecki: Isolation and characterization of nutrients and value-added products from snow crab (Chionoecetes opilio) and shrimp (Pandalus borealis) processing discards. In: Journal of Agricultural and Food Chemistry. 39, No. 8, 1991, pp. 1527-1532. doi: 10.1021 / jf00008a032
Web links
- J. Siegel: Chionoecetes opilio 2013 at Animal Diversity Web
- Alaska snow crab at www.fishwatch.gov
- Snow crab at Tierdoku.com - the interactive animal lexicon