Opilio crab | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Decapoda |
Suborder: | Pleocyemata |
Infraorder: | Brachyura |
Family: | Oregoniidae |
Genus: | Chionoecetes |
Species: | C. opilio |
Binomial name | |
Chionoecetes opilio (O. Fabricius, 1788) | |
Synonyms [1] | |
|
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.
Snow crabs have equally long and wide carapaces, or protective shell-coverings, over their bodies. Their tubercles, or the bodily projections on their shells, are moderately enclosed in calcium deposits, and they boast hooked setae, which are rigid, yet springy, hair-like organs on their claws. Snow crabs have a horizontal rostrum at the front of the carapace; the rostrum is basically just an extension of the hard, shell covering of the carapace and it boasts two flat horns separated by a gap. They have triangular spines and well-defined gastric and branchial regions internally. [2] Snow crabs also have little granules along the border of their bodies, except their intestinal region. Concerning their walking legs, their first three are compressed; their chelipeds, or pincers, are usually smaller, shorter, or equal to their walking legs. [3] Snow crabs are iridescent and range in color from brown to light red on top and from yellow to white on the bottom, [1] and are bright white on the sides of their feet. [4]
Snow crabs are native to the Northwest Atlantic and the North Pacific. In the Northwest Atlantic, they are found in the areas near Greenland, Newfoundland, in the Gulf of St. Lawrence, and on the Scotian Shelf. [2] In the North Pacific, this crab is found in areas ranging from Alaska to northern Siberia, and through the Bering Strait to the Aleutian Islands, Japan, and Korea. [5]
In 1996, they were recorded in the Barents Sea for the first time. They are considered an invasive species there, but how they arrived there is unclear. [6] Another commercially important species, introduced deliberately to the same region, the red king crab, already has established itself in Barents Sea. Similarly, snow crabs likely will have an adverse effect on the native species of the Barents Sea. [6]
Snow crabs are found in the ocean's shelf and upper slope, on sandy and muddy bottoms. [3] They are found at depths from 13 to 2,187 m (43 to 7,175 ft), but average is about 110 m (360 ft). [7] In Atlantic waters, most snow crabs are found at depths of 70–280 m (230–920 ft). [3] Where male and female snow crabs are found in the ocean, depths may vary. Small adult and senescent adult males occur mainly at intermediate depths over much of the year, while large and hardy adult males are found mostly at depths greater than 80 m (260 ft). Adult females are gregarious and congregate at depths of 60–120 m (200–390 ft).[ citation needed ] Snow crabs mainly reside in very cold waters, between −1 and 5 °C (30 and 41 °F), but can be found at temperatures up to 10 °C (50 °F). [7]
Chionoecetes opilio crabs eat other invertebrates in the benthic shelf, such as crustaceans, bivalves, brittle stars, polychaetes, and even phytobenthos and foraminiferans. Snow crabs also are scavengers, and aside from preying on other benthic shelf invertebrates, they prey on annelid worms and mollusks. Males typically prove to be better predators than mature females, and prey type depends upon predator size, with the smallest crabs feeding mainly on amphipods and ophiuroids, while the largest crabs feed mainly on annelids, crustacean decapods, and fish. [8] Cannibalism is practised at times among snow crabs, most frequently by intermediate-sized females.
The snow crab grows slowly and is structured according to its size. At least 11 stages of growth for male crabs are recognized. Usually, the male crabs are almost twice the size of the female crabs. [4] Males can grow up to 16.5 cm (6.5 in) in carapace width, while females can grow up to 9.5 cm (3.7 in). [7] Male carapaces are usually about 7 cm (2.8 in) in width and length, with the female carapace usually close to 5.5 cm (2.2 in) in width and length. [4] Males caught in commercial fisheries generally weigh 0.5–1.35 kg (1.1–3.0 lb) and females generally about 0.5 kg (1.1 lb). [7]
Off the coast of Newfoundland, two amphipod species – Ischyrocerus commensalis and Gammaropsis inaequistylis – have been found to live on the carapace of the snow crab. [9]
Snow crabs have a very high reproductive potential; each year, every female carries eggs. Females are fertilised internally and can carry up to 150,000 eggs under their abdomens after mating. Females usually lay their eggs in very deep areas of the ocean, such as in deposits of phytodetritus. Males also are capable of mating at both immature and mature stages of their lives. [10]
Snow crabs have an average lifespan of 14 to 16 years. Before their deaths, they usually moult, mate a final time, and die. New snow crab offspring hatch along with the late spring phytoplankton bloom, so they have an ample food source to take advantage of upon hatching. When they hatch, they are in the zoeal stage, meaning that they are developing into larvae that can swim on their own. Then, they metamorphose into the megalopa stage and settle to the ocean floor among the phytodetritus.
This species of crab was commonly caught by trappers in the 1980s, but trapping has decreased since then. Much of the trapping has been in Canada for commercial use. [11] The first commercial fishing for the species in the Barents Sea (where it is an invasive species) began in 2013, and the stock of this region likely will reach levels similar to eastern Canada in the future. [6]
Since 2016, the snow crab is at the center of a dispute over fishing rights between Norway and the EU. The EU is of the view that the crab can be freely caught by EU fishers in the international waters in the Barents Sea. Norway, for its part, argues that the crab is not a fish but a sedentary species, and therefore subject to the jurisdiction Norway exercises over the continental shelf. The Norwegian Supreme Court adopted this view in a 2019 decision. [12]
In 2022, the Alaska Department of Fish and Game (ADF&G) banned commercial fishing of snow crabs in the Bering Sea for the first time for the 2022/23 season. [13] The reason for this was the sharp decline in the population. It shrank from about eight billion in 2018 to one billion animals in 2021. The causes are overfishing as well as increased water temperatures as a result of climate change. [14] Cancellation of the crab fishery has significant implications for fishermen, industry, and communities. [15]
The species was first described by Otto Fabricius in 1780, under the name Cancer phalangium, [16] a name that was invalid due to Johan Christian Fabricius having used it previously for the species now known as Inachus phalangium . [17] The first valid scientific name was provided by Otto Fabricius in 1788, when he redescribed the species as Cancer opilio. The type locality is Greenland. [17]
As the genus Cancer was divided up, the species C. opilio was transferred to a new genus, Chionoecetes by Henrik Nikolai Krøyer in 1838. C. opilio was the only species in the genus at first, so it is the type species.
Mary J. Rathbun described a subspecies, C. o. elongatus, in 1924. This is now generally recognised as a full species, Chionoecetes elongatus . [18]
The capelin or caplin is a small forage fish of the smelt family found in the North Atlantic, North Pacific and Arctic oceans. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans. Among others, whales, seals, Atlantic cod, Atlantic mackerel, squid and seabirds prey on capelin, in particular during the spawning season while the capelin migrate south. Capelin spawn on sand and gravel bottoms or sandy beaches at the age of two to six years. When spawning on beaches, capelin have an extremely high post-spawning mortality rate which, for males, is close to 100%. Males reach 20 cm (8 in) in length, while females are up to 25.2 cm (10 in) long. They are olive-coloured dorsally, shading to silver on sides. Males have a translucent ridge on both sides of their bodies. The ventral aspects of the males iridesce reddish at the time of spawn.
The Dungeness crab makes up one of the most important seafood industries along the west coast of North America. Its typical range extends from Alaska's Aleutian Islands to Point Conception, near Santa Barbara, California. Dungeness typically grow 6–7 in (150–180 mm) at their widest point and inhabit eelgrass beds and sandy bottoms. Its common name comes from the Dungeness Spit in the Strait of Juan de Fuca, Washington state, United States, which shelters a shallow bay inhabited by the crabs.
Chionoecetes is a genus of crabs that live in the northern Pacific and Atlantic Oceans.
The Tasmanian giant crab, also known as the giant deepwater crab, giant southern crab, queen crab, or bullcrab, is a very large species of crab that resides on rocky and muddy bottoms in the oceans off Southern Australia. It is the only extant species in the genus Pseudocarcinus.
The Jonah crab is a marine brachyuran crab that inhabits waters along the east coast of North America from Newfoundland to Florida. Jonah crabs possess a rounded, rough-edged carapace with small light spots, and robust claws with dark brown-black tips. The maximum reported carapace width for males is 8.7 in (222 mm), while females rarely exceed 5.9 in (150 mm). It is the closest relative to the European brown crab in the Western Atlantic.
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.
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.
Latreilliidae is a small family of crabs. They are relatively small, long-legged crabs found on soft bottoms at depths of up 700 metres (2,300 ft) in mostly tropical and subtemperate waters around the world. Their carapace is very small and doesn’t cover the bases of their legs, which protrude from the cephalothorax in a spider-like manner. The family and its type genus are named after Pierre André Latreille. The oldest known fossils from the Latreillidae have been dated to the middle of the Cretaceous period. It comprises seven extant species.
Crab fisheries are fisheries which capture or farm crabs. True crabs make up 20% of all crustaceans caught and farmed worldwide, with about 1.4 million tonnes being consumed annually. The horse crab, Portunus trituberculatus, accounts for one quarter of that total. Other important species include flower crabs, snow crabs (Chionoecetes), blue crabs, edible or brown crabs, Dungeness crab, and mud crabs, each of which provides more than 20,000 tonnes annually.
Cod fisheries are fisheries for cod. Cod is the common name for fish of the genus Gadus, belonging to the family Gadidae, and this article is confined to three species that belong to this genus: the Atlantic cod, the Pacific cod and the Greenland cod. Although there is a fourth species of the cod genus Gadus, Alaska pollock, it is commonly not called cod and therefore currently not covered here.
Hematodinium is a genus of dinoflagellates. Species in this genus, such as Hematodinium perezi, the type species, are internal parasites of the hemolymph of crustaceans such as the Atlantic blue crab and Norway lobster. Species in the genus are economically damaging to commercial crab fisheries, including causing bitter crab disease in the large Tanner or snow crab fisheries of the Bering Sea.
Paralithodes platypus, the blue king crab, is a species of king crab from cold waters in the North Pacific Ocean and adjacent seas. Although blue king crabs are among the largest crabs in the world and reputedly may exceed 18 pounds (8.2 kg) in weight, they are generally smaller than red king crabs.
Palinurus mauritanicus is a species of spiny lobster. It is found in deep waters in the eastern Atlantic Ocean and the western Mediterranean Sea.
Inachus phalangium, Leach's spider crab, is a species of crabs from the north-eastern Atlantic Ocean and Mediterranean Sea. It is up to 20.5 mm (0.81 in) wide, and is very similar to other species in the genus Inachus.
Munida rugosa, commonly known as the rugose squat lobster or plated lobster, is a species of decapod crustacean found in the north east Atlantic Ocean and the Mediterranean Sea.
Neolithodes is a genus of king crabs, in the family Lithodidae. They are found in all major oceans, both in high and low latitudes. Although there are records from water as shallow as 124 m (407 ft) in cold regions, most records are much deeper, typically 700–2,000 m (2,300–6,600 ft), with the deepest confirmed at 5,238 m (17,185 ft). They are fairly large to large crabs that typically are reddish in color and spiny, although the size of these spines varies depending on species.
Macrourus berglax, also known as the roughhead grenadier or onion-eye grenadier, is a species of marine ray-finned fish in the family Macrouridae. It is a deep-water fish found in the Atlantic Ocean.
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.
Neolithodes grimaldii, the porcupine crab, is a species of king crab in the family Lithodidae. This large red crab is found in cold deep waters in the North Atlantic and often caught as a bycatch in fisheries for Greenland turbot. As suggested by its common name, the carapace and legs are covered in long spines.
Chaceon quinquedens, commonly known as the red deep-sea crab, but sold as Atlantic deep sea red crab, or simply Atlantic red crab or red crab, is a crab that lives in the Atlantic Ocean off the East Coast of the United States and Canada, from North Carolina to Nova Scotia, and in the Gulf of Mexico.