Paul Bentzen Lab

PhD project, Megan McCusker

Three species of wolffishes (Anarhichas) inhabit the North Atlantic Ocean, all of which have interesting and unusual life histories. For example, wolffishes are thought to form monogamous mating pairs, they exhibit paternal care of young, and they have some of the largest eggs of any marine fishes (up to 8 mm in diameter for northern wolffish). Wolffishes make nests on the rocky substrate of the ocean bottom and the eggs are guarded by the male until hatch, which in Atlantic wolffish can be up to 9 months in some areas. Larvae, which hatch at approximately 20 mm in length, are not neutrally buoyant and may be able to control their own movement to a large degree. Thus, wolffish eggs and larvae are much less subject to drift by ocean currents than those of other marine fishes with pelagic eggs and larvae that float at the surface for months. As adults, wolffishes are benthic and fairly sedentary, suggesting that they may have highly distinct populations.

Many of these life history characteristics that make wolffishes interesting also make them particularly vulnerable to fishing mortality and habitat degradation by trawl nets. Due to a combination of extensive habitat degradation and by catch in other fisheries, wolffishes in the Atlantic Ocean have suffered severe population declines since the 1970s. All three species of wolffishes in the Atlantic are currently listed under the Canadian Species at Risk Act (SARA) as either special concern (Atlantic wolffish, Anarhichas lupus) or threatened (spotted wolffish, A. minor, and northern wolffish, A. denticulatus).