Atlantic wolffish, Anarhichas lupus.

Atlantic Wolffish, Anarhichas lupus

The Atlantic wolffish was given its scientific name by Linnaeus in 1758. It is distinguished from its Atlantic and Arctic relatives by the colour pattern. Overall body colour is variable from blue-grey to yellowish-green or purple-grey. The sides and dorsal fin of the fish have 9–13 vertical, dark-brownish, irregular bars while the belly is a dirty white. The placement and pattern of teeth are also a distinguishing feature; in the centre of the upper jaw is a bone known as the vomer, which is flanked on each side by a palatine bone. In the wolffish family, teeth are found on both the vomer and the palantines. The feature that distinguishes the Atlantic wolffish is that the teeth on the vomer bone extend back beyond the palantine teeth at the sides. Other characteristics, such as body size and shape, fin placement, and head size are similar to that of the other wolffishes. Its dorsal fin extends the length of the back, its caudal fin is rounded, its anal fin runs the length of the belly, and its pectoral fins are large and fan like. Its body grows to a length of no more than 152 cm.

The Atlantic wolffish's distribution in the Canadian Arctic is limited to Davis Strait, but it also occurs through the Gulf of St. Lawrence and south to New Jersey. It is more common in the southern part of its range than in the north. In the Arctic, it stays inshore, while in the south, it occurs at depths ranging from 22–366 m. This species tolerates temperatures in the range of -1°C to 13°C.

Inshore migration precedes fall spawning by several months in this species, and breeding occurs in specific regions, such as the LeHave Bank. This area is believed to be an Atlantic wolffish nursery based on the presence of numerous egg masses in March. Copulation takes place over a 3–6 hour period and fertilization is internal, with the female releasing her eggs 7–15 hours after mating. These eggs are large, some having a diameter of 6.5 mm. The larvae remain in the water column until they are 5–6 cm long, and then descend to the bottom to begin an adult existence.

Food items include starfish, molluscs, various crustaceans, and the odd redfish, but green sea urchins dominate, comprising almost 75% of its diet. Because the majority of its prey are hard-shelled, the wolffish uses two types of teeth to consume its prey. The teeth at the front of the mouth are only used for capture while the rear, molar-like teeth are used to crush and grind the prey. Wolffishes are themselves consumed by Atlantic cod. Human consumption of wolffish is limited to incidental catches from trawlers fishing for groundfish, but some 3109 tonnes were caught in 1984. Although the flesh has been described as "excellent", wolffish is often marketed as catfish, which is considered a more palatable and familiar name.

Atlantic wolffish become sexually mature at 8 to 10 years of age, at a length of about 50–60 cm. As young wolffish are rarely found in shallow waters, it is thought that they stay in deeper waters until mature. Males may mature more slowly than females and, in some cases, have not become sexually active until they are 70 cm long. On average, individuals live for 22 years.