Atlantic Wolffish | Oceana Canada

Canadian Marine Life Encyclopedia

Atlantic Wolffish

Anarhichus lupus

Also known as

Striped wolffish, seawolf, seacat, ocean catfish

Distribution

Cold temperate to subpolar north Atlantic Ocean

Écosystèmes/habitats

Rocky reefs and hard bottoms

Feeding Habits

Aggressive predator

Conservation Status

Special concern/data deficient

Taxonomie

Order Cottiformes (sculpins & relatives); Family Anarhichadidae (wolffishes)

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With even just a brief glance, you can quickly figure out how the Atlantic wolffish was named. Their large, canine-like teeth protrude from their mouths, giving them a wolf-like scowl. Behind these visible primary canine teeth are a cluster of five or six smaller canines, as well as three sets of crushing teeth on the roof of their mouths, used to grindhard-shelled prey. In spite of their slightly ferocious appearance and large teeth, Atlantic wolffish are not aggressive. They feed on slow-moving or sedentary prey such as sea urchins, crabs, molluscs and large snails. Atlantic wolffish are also incredibly well-adapted for cold water conditions, able to survive in water below 0°C, thanks to high concentrations of an antifreeze compound in their blood.

Atlantic wolffish are a fairly large fish with an elongated, tapering body and weigh up to almost 20 kilograms. Their heads are relatively large compared to their bodies and they have blunt, rounded snouts with sharp, protruding teeth. Their dorsal fins run down their back, starting behind the head and extending all the way to the tail fin, however they lack pelvic fins which most fish have. Atlantic wolffish are typically a light greyish-green colour, but can range from olive green to purplish- or reddish-brown. They are one of three species of wolffish that can be found in Atlantic Canada, the other two being Spotted and Northern. Atlantic wolffish can be distinguished from their wolffish cousins by the nine to 13 darkly coloured, vertical bars that run the length of their body. 

Atlantic wolffish become sexually mature in the northwest Atlantic at around eight to 10 years of age. They will form bonded pairs during the spring and summer and mate via internal fertilization in the fall. Females will reproduce multiple times through their lifetime, laying between 5,000 and 12,000 eggs. The number of eggs a female is able to lay increases with her size, which is why it is vitally important that large females remain in the environment to ensure population sizes are healthy. Eggs are laid in a cluster on boulders and in rocky crevices, where they will be guarded by the parental male until they hatch. Males that are guarding eggs will stop feeding and become more aggressive in their duties as a protector. Once hatched, the rather large larvae float around in the upper layers of the water column before settling to the ocean floor as juveniles. They settle into a sedentary lifestyle as they mature, setting up home in crevices on rocky reefs, only really venturing out for food or to find a mate during the spawning season. Atlantic wolffish can live to be around 20 years old.

There are no fisheries targeting Atlantic wolffish in Canada, however they are commonly caught as bycatch (the catch of non-targeted species) in commercial bottom-trawl and trap fisheries. They were caught in relatively high numbers in the 1970s, but catches have drastically declined since the late 1980s and 1990s, corresponding with many of the groundfish closures during this time in Atlantic Canada. Bottom contacting fishing gears, like bottom-trawls and dredges, are also thought to destroy habitat that is important for wolffish.

Atlantic wolffish were assessed and listed as a Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2000, and re-listed as such in 2012. They were also listed under Schedule 1 of the Species at Risk Act (SARA) as a Special Concern in 2003. Due to their long lifespan, late maturity and low reproduction rates, Atlantic wolffish populations are slow to recover after they have been greatly reduced. This is one of the main reasons for their listings as a Special Concern, as the population of Atlantic wolffish in Canadian waters declined by 87 per cent from the late 1970’ to the mid 1990s. However, with reduced fishing pressure as a result of groundfish fishery closures and improved bycatch reduction measures, Atlantic wolffish are still fairly widespread and populations are believed to be increasing.