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Seawolf (fish)

The Atlantic wolffish (Anarhichas lupus), also known as the Seawolf, Atlantic catfish, wolf eel (the common name for its Pacific relative), or sea cat, is a marine fish, the largest of the wolffish family Anarhichadidae. The numbers of the Atlantic wolffish are rapidly depleting due to overfishing and by-catch, and is currently a Species of Concern according to the National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service (NMFS). Although it is a fearsome looking creature, the Atlantic wolffish is only a threat when defending itself outside of the water. Besides for its unique appearance, some of its distinguishing characteristics include: the natural antifreeze it produces to keep its blood moving fluidly in the very cold water where it lives, a mutual effort by both the female and male in brood bearing and the large size of their eggs. They are also an important factor in keeping green crab and sea urchin numbers down, who can become an invasive species when their population size gets too big. Their population success is also an important indicator on the health of other bottom dwellers populations, such as cod.

Description

In spite of its large size the Atlantic wolffish has retained the bodily form and general external characteristics of small blennies (Blennioidei). The largest specimen recorded measured 150 cm (almost 5 ft) long and weighed almost 18 kg (40 lbs) Its body is long, subcylindrical in front, compressed in the caudal portion, smooth and slippery, the rudimentary scales being embedded and almost hidden in the skin. Altantic wolffish vary in color, usually seen as purplish-brown, a dull olive green, or blueish gray. An even dorsal fin extends the whole length of the back, and a similar fin from the vent to the caudal fin, as in blennies. The pectorals are large and rounded and the pelvic fins are entirely absent. Its obtuse eel-like body type makes the fish swim slowly, undulating from side to side, like an eel.

The Atlantic wolffish's distinguishing feature (and from where it gets its common name) is its extensive teeth structure. Its dentition (teeth) distinguishes the Atlanitic wolffish from all the other members of the Anarhichadidae family. Both the lower and upper jaw are armed with four to six fang-like, strong conical teeth. Behind the conical teeth in the upper jaw, there are three rows of crushing teeth. The central row has four pairs of molars and the outer rows house blunted conical teeth. The lower jaw has two rows of molars behind the primary conical teeth. The wolffish's throat is also serrated with scattered teeth.

Range and Habitat

The Atlanitic wolffish habituate both the West and East coasts of the Atlantic. The are seen as far north as the Davis Strait, of the Canadian territory of Nunavut, populating the shores of Greenland and Nova Scotia, extending down as far as Cape Cod. Although they are seldom seen south of Cape Cod, there have been sitings in New Jersey. The most dense populations of wolffish are in Georges Bank, the Gulf of Maine and the Great South Channel.

The Atlanitc wolffish are primarily stationary fish, rarely moving from their rocky home. They are benthic dwellers, living on the hard ocean floor, frequently seen in nooks and small caves. They like cold water, at depths of 76 to 120 meters (250 to 400 ft). They are usually found in waters of 34-36°F (1-2°C) and sometimes as low as 30°F (-1°C). Since they live in nearly freezing waters, in order to keep their blood moving smoothly, their blood contains a natural antifreeze.

Altantic wolffish are inhabitants of the northern seas of both hemispheres, being common on the coasts of Scandinavia and North Britain, and also in the seas around Iceland and Greenland. Two related species occur in the corresponding latitudes of the North Pacific Ocean. In the north they are esteemed as food, both fresh and preserved. They are marketed as "Scotch Halibut" and "Scarborough Woof", or, simply "Woof" in other areas of the North East coast, and are a popular ingredient in fish and chips. The oil extracted from the liver is said to be equal in quality to the best cod liver oil.

In Icelandic, the Seawolf is called Steinbitur, which literally translates to "stone biter".

Diet

Atlantic wolffish use their strong jaws to eat hardshell mollusks, crustaceans, and echinoderms. They do not eat other fish. They are known to frequently eat large welks (Buccinum), cockle (bivalve) (Polynices, Chrysodomus and Sipho), sea clams (Mactra), large hermit crabs, starfish, sea urchins and green crabs (Carcinus maenas). They are an important predator of sea urchins and green crabs, whose populations escalate rapidly and can negatively effect the health of a marine system.

Reproduction

The manner of which Atlantic wolffish fertilize their eggs distinguishes them from many fish. Instead of the female depositing her eggs in the open ocean for the male fish to fertilize and then continue on his way, they are internally fertilized and the male wolffish stays with the nest and protects the eggs for as long as four months, until the brood is strong enough to gain independence. Their eggs are 5.5-6 mm in diameter, (among the largest fish eggs known), yellow tinted and opaque. The eggs are laid on the ocean floor, many times in shoal water, sticking together in loose clumps, surrounded by seaweed and stones. Altantic wolffish mature relatively late, at age six.

Conservation Status

According to scientific data, the Atlantic wolffish's population has decreased drastically due to overfishing and by-catch. Bottom trawling vessels also disrupt the wolffish's rocky underwater habitat when they drag large nets across the ocean floor, with heavy weights holding the nets to the ocean bottom. The nets are indiscriminate in what they catch and the heavy weights and nets are harmful to the benthic terrain and its inhabitants. Recreational fishing has also threatened the survival of the Atlantic wolffish.

According to data compiled by the National Marine Fisheries Service, since 1983 the landings from U.S. fishing vessles of Atlantic wolffish as by-catch has declined 95% landing 64.7 metric tons (mt) in 2007. In 1950, when the NMFS started collecting their data, 1,098 mt of Atlantic wolffish were landed, worth $137,008. In 1970, 271.2 mt; the landings peaked in 1983 at 1,207 mt, bringing in $455,291; rapidly depleting again and by 1990 the landings were down to 400 mt and by 2002, 154 mt. The last available data from the NMFS was in 2007 at 64.7 mt, worth a total of $100,341.

Currently, the Atlantic wolffish is categorized as a Species of Concern under the National Marine Fisheries Service. On October 1, 2008, the Conservation Law Foundation (CLF), along with Dr. Erica Fuller and Dr. Les Watling, petitioned the National Marine Fisheries Service for the proctection of the Atlantic wolffish under the Endangered Species Act (ESA). The petition called for the protection of the Atlantic wolffish and wolffish habitat throughout the US northwest Atlantic waters. It recommended that there be a designation of critical habitat that closes off both commercial and recreational fishing in those areas (which would overlap closed areas for various other fishing industries for the benefit of fishermen), the development of catch and release protocols, educational programs for fishermen in the Gulf of Maine area, and possession prohibitions.

References

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