The Portuguese dogfish (Centroscymnus coelolepis) is a deepwater, bottom-associated shark found along continental slopes and in the Gulf of St. Lawrence. Like the much larger Greenland shark, it belongs to the sleeper shark family (Somniosidae). The species has been recorded at depths of up to 3,675 m[1], making it one of the deepest-dwelling shark species known.

Because it inhabits depths far beyond the reach of recreational divers, observations of the Portuguese dogfish are generally limited to incidental captures by deepwater trawlers and other fishing gear.

The species is often confused with the similar-looking black dogfish, although the latter possesses larger and more conspicuous dorsal spines in front of each dorsal fin.

The Portuguese dogfish may be a year-round resident of the Gulf of St. Lawrence, alongside the black dogfish and Greenland shark[2], although available data remain insufficient to clearly determine its status in the region.

(1) Compagno, L.J.V., 1984. Sharks of the world: an annotated and illustrated catalogue of shark species known to date, 4(1). FAO species catalogue
(2) There are two known outlier cases of the spiny dogfish (Squalus acanthias) being caught by ice fishers in the Saguenay Fjord in winter (Gallant, J., unpublished data).

• Maximum length of approximately 1 m.
• Light- to dark-brown coloration, generally paler than the closely related black dogfish.
• Large oval eyes equipped with a reflective layer (tapetum lucidum) that enhances vision in deep water and produces a yellow-green reflection.
• Small grooved spines positioned in front of both dorsal fins, similar to those of the black dogfish and spiny dogfish.
• Anal fin absent.
• Deepwater, bottom-associated species typically found below 400 m.
• Possible year-round presence in Atlantic Canada and Québec, including the Gulf of St. Lawrence.

In Atlantic Canada, the Portuguese dogfish occurs along the continental shelf and within the Gulf of St. Lawrence. Globally, it is one of the most widely distributed deepwater sharks, occurring in temperate and tropical waters around the world. The species may be a year-round resident of the Gulf of St. Lawrence, alongside the black dogfish and Greenland shark, although available data remain insufficient to clearly determine its status in the region.

The Portuguese dogfish (Centroscymnus coelolepis) has not been assessed by COSEWIC (Committee on the Status of Endangered Wildlife in Canada) and is not currently listed under Canada’s Species at Risk Act (SARA). In Canada, the species remains poorly studied because of its deepwater habitat, and relatively little is known about its abundance or long-term population trends in Atlantic Canadian waters.

Globally, the Portuguese dogfish is classified as Near Threatened by the International Union for Conservation of Nature (IUCN). The species is considered vulnerable to overexploitation because of its slow growth, low reproductive rate, and susceptibility to deepwater fisheries. Its conservation status is of particular concern because deepwater sharks generally recover very slowly from population declines.