The spiny dogfish (Squalus acanthias) is a coastal squaloid shark with a broad circumboreal distribution in temperate and cold waters. In the western North Atlantic, it ranges from Labrador to Florida, although it is particularly abundant from Nova Scotia to Cape Hatteras, North Carolina[1]. The species is highly migratory and often travels in immense schools composed of hundreds or even thousands of individuals[2].

Despite its abundance, the spiny dogfish is biologically vulnerable to overfishing. It matures slowly, grows gradually, produces relatively small litters, and has one of the longest gestation periods known among vertebrates, lasting close to two years.

Although several populations declined significantly because of intensive fishing pressure during the twentieth century, the spiny dogfish remains one of the most abundant and widespread shark species in the world.

(1) Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. U. S. Fish Wildl. Serv., Fish. Bull. 53. 577 p.
(2) Rago, J.P., K. Sosebee, J. Brodziak, and E.D. Anderson. 1994. Distribution and dynamics of northwest Atlantic spiny dogfish (Squalus acanthias). Northeast Fish. Sci. Cent. Ref. Doc. 94-19.

The spiny dogfish occurs throughout the Gulf of St. Lawrence and extends into the St. Lawrence Estuary and Saguenay Fjord. In the St. Lawrence region, the species is typically seasonal, arriving in late spring or early summer and departing by late autumn or early winter. Although uncommon during winter months, two exceptional records document spiny dogfish captured by ice fishers in the Saguenay Fjord during January and February (Gallant, J., unpublished observations). The timing and duration of the species’ annual migration into the St. Lawrence may shift in response to warming ocean conditions associated with climate change.

According to the Canadian Shark Attack Registry, there are no confirmed incidents involving spiny dogfish (Squalus acanthias) and humans in Canadian waters. The species is considered harmless to people under normal circumstances due to its relatively small size and feeding habits, which primarily focus on fish and invertebrates such as squid and crustaceans.

However, spiny dogfish can become highly active and competitive when concentrated in large feeding schools. Recreational divers and fishers have occasionally reported “nippy” behaviour when the sharks are attracted by bait, discarded fish, or intentional feeding activities. In these situations, individuals may bump or nip opportunistically while competing for food. Although such behaviour can result in minor injuries from the teeth or dorsal fin spines, interactions with humans remain rare and are not considered predatory in nature.

(1) Gallant, J. (2022. July 26). Canadian Shark Attack Registry (1st ed.). St. Lawrence Shark Observatory.

The spiny dogfish is the subject of a directed fishery in Atlantic Canada; however, reported landings in the St. Lawrence region are generally considered low. Despite its abundance, the species remains vulnerable to overexploitation due to its slow growth, late maturity, and low reproductive rate.

The spiny dogfish (Squalus acanthias) is currently listed as Special Concern by COSEWIC (Committee on the Status of Endangered Wildlife in Canada). Although populations in Atlantic Canada have shown signs of recovery following historical declines caused by overfishing, the species remains vulnerable because of its extremely slow reproductive cycle, late maturity, low reproductive output, and unusually long gestation period.

Globally, the spiny dogfish is classified as Vulnerable by the International Union for Conservation of Nature (IUCN). Severe population declines have occurred in several parts of the world as a result of intensive commercial fishing for meat, fins, and liver oil. Because the species reproduces slowly and forms large schools, local populations can be depleted rapidly and may require decades to recover.

In Atlantic Canada, directed fisheries for spiny dogfish remain regulated through quotas and management measures intended to prevent overexploitation and promote long-term population stability.