Black dogfish

How it lives

It gives birth to live young that feed on yolk, in litters of 4 to 40 pups, with no clear breeding season. Off western Greenland males matured at about 55 cm and females at about 65 cm. Sexes and sizes are spread over different depths. It has small light-producing organs scattered over its dark skin. In Canadian waters, trawl surveys show the Laurentian Channel is a pupping and nursery ground. Lifespan is not given in the sources I opened.

Where it goes

It lives on or near the bottom of the outer continental shelf and slope, usually at 180 to 2,250 m, and may come closer to the surface in winter at high latitudes. In Canadian waters, young sharks are found in the Laurentian Channel. As they grow they shift out to the slope over several years, a movement of about 4,000 km, with the largest sharks furthest from the Channel. Patterns in Greenland and Iceland differ.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

IUCN Least Concern globally (assessed 2019, published 2020), but the species has been assessed as Near Threatened in the north-eastern Atlantic, where numbers may have fallen because of fishing pressure. The north-western Atlantic population appears stable. It is caught as bycatch in deep-sea fisheries, usually discarded and increasingly kept for fishmeal. FishBase rates it as having low resilience and high to very high vulnerability to fishing. In Greenland, size at first maturity fell by about 10 cm over 25 years, a change the authors link in part to bycatch in the Greenland halibut fishery, though they say method and environment may also play a part. I did not find a total population count.