Diagnostic features 

Upper jaw slightly longer than lower. Barbel present on chin; none on snout.  Single, longbased dorsal and anal fins, partly connected at their posterior ends to the rounded caudal fin; pectoral fin failing far short of anal fin origin. No elongated rays in the fleshy pelvic fin.  Lateral line continuous until slightly before the caudal peduncle. Lateral line pores present on head.  Colour: variable; dorsally dark red-brown or green-brown to yellow shading into pale colour on belly. Young fish may have six transverse yellow bands on sides. The most characteristic colour pattern is on the vertical fins, which have dark margin rimmed with white. 

Western north Atlantic from New Jersey to the Strait of Belle Isle and on the Grand Banks of Newfoundland. Rare at the southern tip of Greenland. Found off Iceland, in the northern North Sea, and along the coasts of Scandinavia to the Murmansk Coast and at Spitzbergen. 

 

The tusk lives alone or in small shoals on rough, rock, gravel, or pebble bottoms of both sides of the North Atlantic. In the Gulf of Maine, it is occasionally found on mud with hakes, and in Norwegian waters, it often lurks among gorgonian corals. Seldom found on smooth, clean sand.Generally keeps far from the shore, near the bottom, at depths from 20 to 1 000 m, mostly between 150 and 450 m in the northeastern Atlantic (except in the Faeroe Channel where it has been caught at 954 m), and between 18 and 549 m in the northwestern Atlantic. Never found near the shore or at depths of less than 20-30 m.  It tolerates a temperature range from 0 to 10°C.  The tusk moves little from bank to bank and there is no definite evidence of seasonal onshore or offshore migrations. While remaining in the same region, it undertakes only local migrations from greater to lesser depths. It is found alone or in small aggregations, not forming large schools such as do other gadoids. First maturity is reached at 8-10 years (50 cm length).  Tusk is among the more prolific of fishes and a female of medium size can lay up to 2 million eggs which develop close to the surface. Spawning occurs in spring and early summer (April to July) on both sides of the Atlantic. Spawning grounds are distributed practically throughout the entire range, but the most important ones are between Scotland and Iceland. In the eastern Atlantic, they are located on the edge of the Shetland Islands, Faeroes and Iceland slopes, from 200 to 500 m depth, and in the northern part of the North Sea, along the 100-200 m isobaths.

The maximum size is 110 cm although cusk is more common from 60 to 95 cm in the eastern, and from 50 to 80 cm in the western North Atlantic.

Fisheries 

Tusk is caught with otter trawls and on hard bottoms, with longlines. It is also taken in the Gulf of Maine by sportsmen fishing for groundfish in general.).  Utilization: fresh or frozen as fillets, but also dried, salted, and in brine.