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Description of spiny dogfish
This shark generally measures 80 to 100 centimetres, sometimes reaching 1.6 metres. Its body is slender and elongated, slate-gray to brownish on the back with white lateral spots in juveniles, and pale white on the belly. Spiny dogfish have two dorsal fins preceded by venomous (non-lethal) spines, triangular pectoral fins and oblique teeth with a single cusp forming a sharp edge.
Habitat and behavior
The spiny dogfish is a regular species, forming vast shoals monosexed by size. They can be found in the Atlantic, Pacific and Mediterranean, from the surface to 900 meters below the surface, often near coasts or on sandy bottoms. Migratory, they follow currents to feed on fish (herring, sand eels), crustaceans and cephalopods. It reaches maturity at 5-10 years of age and can live up to 100 years, albeit very slowly.
Reproduction
Ovoviviparous, the female spiny dogfish carries 2 to 15 embryos for 18 to 24 months (the longest known gestation period among vertebrates). The young are born alive at 25-35 centimetres after 2 years of internal development. Reproduction is biennial (taking place every two years), contributing to its vulnerability.
Human importance
Fished for its meat (particularly shark fillets), fins and liver oil, the spiny dogfish is threatened by overfishing. Classified as near-threatened (IUCN), its Atlantic stocks are declining despite quotas. Although not dangerous to humans, its spines can cause painful bites. A species to be handled with care. In France, it frequents the Atlantic and Mediterranean coasts.
Conservation
The spiny dogfish or Squalus acanthias is unfortunately one of these overexploited populations in Europe, despite partial harvesting bans, notably in the European Union.
Efforts to set sustainable quotas and establish marine protected areas are still needed to preserve this species. Indeed, the longevity of the spiny dogfish remains a precious indicator of the health of marine ecosystems.
