Spiny Dogfish

Squalus acanthias is a slender, medium-sized shark identifiable by two dorsal spines and a lack of an anal fin, along with white-spotted grey flanks. Named for these venomous spines, which offer defense against predators, this species is highly migratory and often travels in large, sex-segregated schools. As a mid-to-upper trophic level predator, it feeds on small fish, squid, and crustaceans, helping regulate prey populations in the marine food web.

It is among the slowest-reproducing sharks, with gestation periods lasting up to two years, making population recovery inherently slow.

This species inhabits temperate and boreal marine waters, typically over continental shelves and in coastal to offshore zones, from surface waters down to several hundred meters. It has a wide distribution across the Southern Hemisphere, including waters off South Africa, New Zealand, and Australia, as well as other temperate regions globally.

Population decline is driven primarily by targeted and incidental capture in commercial fisheries, where it is harvested for meat, fins, and liver oil, or taken as bycatch in aquaculture-adjacent and other fishing operations. Habitat degradation from coastal ecosystem modification, pollution, and activities such as logging-related runoff further stress nearshore environments used by juveniles. Its low reproductive rate makes it particularly vulnerable to sustained fishing pressure.

Conservation measures include regional catch limits, fisheries management plans, and monitoring programs in some range states, alongside international trade considerations for shark products. Enforcement and data collection remain inconsistent across its range.

Current population trends are decreasing, and the species is classified as Vulnerable. Without stronger, consistently enforced management across its full range, continued declines are likely given its slow life history and ongoing exploitation.