The spiny dogfish is a small, schooling shark of the genus Squalus that is frequently encountered when fishing in cold and temperate waters. Their name comes from the two thick spikes that adorn the leading edge of each dorsal fin. When caught, the dogfish will contort its muscular, flexible body in a defensive effort that can result in one of those spikes impaling the hand or arm of an unfortunate fisherman.
Spiny dogfish can be found anywhere in the water column, although they normally remain close to the bottom. As predators, they are generalists, which regularly feed on animals as diverse as herring, squid, comb jellies and various crustaceans.
There is no directed recreational fishery for spiny dogfish on the east coast of the United States, where most anglers see them as a nuisance to be avoided, rather than as a species to be sought. However, if the fish are bled out immediately upon being caught, to prevent the urea in the blood from breaking down and tainting the flesh, and adequately iced, they can be used for food. Although few anglers are yet willing to go through such trouble, the number of fishermen who keep dogfish is slowly growing as declining numbers of some more desirable species, and more restrictive regulations placed on others, has limited the harvest of more valued fish.
Spiny dogfish are not frequently eaten in the United States. Over the years, the National Marine Fisheries Service has tried, on occasion, to encourage the development of a domestic market in which the fish are sold under the presumably more attractive sobriquet of “Cape shark.” Such efforts never gained very much traction, although in recent years some prominent chefs, concerned with the depletion of traditional food species, have created dishes using spiny dogfish and other “underutilized species” that have gained a degree of public acceptance. Spiny dogfish are also featured in some “dock-to-dish” programs in which restaurants and individuals purchase fresh, local fish directly from fishermen or fishing cooperatives.
Thus, almost all of the spiny dogfish caught on the east coast is exported. The meat is sold in the United Kingdom, where it is used in fish and chips, and also in Germany, France and Italy. Fins and tails are marketed in Asia.
The commercial fishery is still characterized by high volumes and low prices. Landings over the past five years averaged about 20,000,000 pounds, less than half of the average annual landings during the late 1990s, when harvest peaked, but about five times greater than the landings of the early 2000s. Prices, however, have remained relatively stable over the past twenty years, with fishermen receiving nineteen cents per pound in 1995, eighteen cents per pound in 2005 and sixteen cents per pound in 2015.
Gill nets account for most of the spiny dogfish landings on the Atlantic coast, although small trawl and bottom longline fisheries also exist. Fishermen, regardless of the gear used, target schools of mature female dogfish, as the larger individuals are preferred by the seafood processors, which find them easier to handle than the smaller fish.
Range and Biology
Spiny dogfish are very common in both the North Atlantic and North Pacific oceans. In the western Atlantic, they can be found between Labrador and Florida, although they occur most frequently between Nova Scotia and North Carolina.
Immature dogfish of the same size tend to school together; once the fish have matured, schools are generally comprised of same-sex fish of similar size. They are, for the most part, fish of the continental shelf, ranging from the shoreline out to the beginning of the continental slope; however, they will also enter protected bays and estuaries, particularly during summer and at the northern end of their range, and there have been reports of spiny dogfish being found in depths in excess of 2,000 feet.
Spiny dogfish are long lived, and reproduce slowly. Some sources suggest that dogfish may live to be 100 years old. Females aren’t sexually mature until about twelve years of age; once mature, they bear live young after a gestation period that may be as long as 24 months. Such a life history can make the dogfish vulnerable to overfishing, although the large number of spiny dogfish in the ocean—they are probably the world’s most abundant shark—provides some buffer against overfishing.
Spiny dogfish fisheries in federal waters are managed by NMFS, acting through the New England and Mid-Atlantic fishery management councils, which have jointly developed a fishery management plan. State-waters fisheries are managed by the Atlantic States Marine Fisheries Commission, which has developed a fishery management plan that is complimentary to, but different from, the federal plan.
The spiny dogfish stock is currently considered to be in good condition, neither overfished nor subject to overfishing. The most recent stock assessment, completed in 2015, found spawning stock biomass to be slightly above the biomass target.
Many believe that the stock is “over-abundant” and that spiny dogfish predation on other depleted species may be contributing to their decline, although there is no science indicating this is the case.