The spiny dogfish is a medium sized dogfish, common size is 70-90 cm. The largest measured in Icelandic waters was 114 cm. It is considered slow growing but can reach an old age, perhaps up to 100 years. The spiny dogfish is a predator as most dogfishes and sharks are. It feeds on a variety of fishes as well as on benthic invertebrates.
It is usually a benthic fish over mud bottom on the continental shelf and slope but is often also seen in the water column. It is highly migratory; individuals tagged in Norwegian and North American waters have been fished in Icelandic waters. The spiny dogfish is probably one of the most common dogfish species in the world, since it occurs world-wide, in the Atlantic and in the southern Pacific as well. Closely related species is found in the Northern Pacific. The spiny dogfish can be found all around Iceland but is rare in the cold waters of the north.
A few hundred tonnes of spiny dogfishes were fished annually by foreign fleets. However, Icelandic catches have always been low, or around 100 tonnes in recent years. The spiny dogfish is in fact considered a pest by Icelandic fishermen, as they claim more valuable fish species disappear from the fishing grounds when the dogfish appears.
The current catches are only bycatch in other fisheries, primarily gillnet fisheries off the southern coast during the summer months.