The Portuguese dogfish (Centroscymnus coelolepis) is a deepwater, benthic species found throughout the continental shelf and into the Gulf of St. Lawrence. Like the much larger Greenland shark, it is a sleeper shark of the family Somniosidae. It has been documented to a depth of 3,675 m¹, making it the deepest-dwelling shark species known to this day.
Observations of this species, which lives far beyond the range of recreational divers, are limited to by-catch by deep trawlers or other fishing apparatus.
The Portuguese dogfish is often misidentified as the black dogfish, which is similar in size and appearance, but whose spines in front of each dorsal fin are larger and more apparent.
The Portuguese dogfish may be a year-round resident of the St. Lawrence along with the black dogfish and Greenland shark², but data is currently lacking to confirm its status.