Spiny dogfish are the world’s most abundant shark species. They tend to travel and feed in large schools like packs of hunting dogs—hence the name “dogfish.” They also have a mildly poisonous spine, used mostly in defense, in front of their two dorsal fins. They can be found in waters all around the world, but prefer temperate waters at depths from 164 to 820 feet (50 to 200 metres).
Spiny dogfish are brown or grey on top, fading to white or grayish-white on their bellies. They also have distinctive irregular white spots on the top or sides of their body. They resemble other sharks in their pointed noses and slender, streamlined bodies. Their skeleton is made of cartilage instead of bones, making their boneless, white fillets popular in British fish and chips.
A small schooling shark, Spiny dogfish are long lived and slow growing, with an estimated life span of 30 to 40 years. This life starts when females produce eggs that hatch within their body. After a gestation period that can last from 18 months to two years – the longest gestation of any other vertebrate – the female then bears live young, producing a litter of between two and 15 “pups.” The number of pups is dependent on the size of the female, but the average litter runs to five or six. These are normally born in the warmer waters of the northeastern United States and Nova Scotia in the Atlantic Ocean and in sounds and inland waterways in the Pacific Northwest. Sexual maturity in males is reached at a total length of about two feet (64 cm) and 10 years of age. Females reach their sexual maturity around 16 years.
Bottom Longline with Hooks
This fishery uses a bottom longline that is baited with hooks and anchored to the ocean floor. A longline can be from 1 to 3 miles (1.6 to 5 km) long and have up to 2,000 hooks.
This fishery uses a large cone-shaped net that is dragged along the seafloor to catch fish. As the net is towed at low speed, hydrodynamic forces push two "otter boards" outwards opening the mouth of the net and capturing fish in its path.