In general, sharks are highly susceptible to overfishing because they cannot reproduce at a rate that supports large harvests. They grow slowly, do not reproduce until late in life, and live a long time. Sharks reproduce in different ways, depending on the species; however, most sharks, including dogfish, bear live young. Compared to other fish that produce millions of eggs, sharks are not very productive, typically only giving birth to a few pups at a time after a gestation period of several months. For these reasons, and the high demand from foreign markets, spiny dogfish populations have been heavily depleted in many areas around the world. Spiny dogfish stocks off both U.S. coasts are currently abundant, thanks to relatively low fishing pressure and precautionary management.
- Ocean perch
- Sea Bass
- Turbot (Greenland)
Pacific Spiny Dogfish
ALSO KNOWN AS:
Shark, Dogfish, Spring Dogfish, Spiked Dogfish, Grayfish, Spur Dog, Picked Dogfish
U.S. wild-caught from Alaska to California
- FISHING RATE
- HABITAT IMPACTS
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Tagged spiny dogfish shark ready for release.LAUNCH GALLERY
Although it’s not a very popular seafood species in the United States, spiny dogfish have been harvested off the West Coast for nearly 1,000 years, starting with the tribal fisheries in Puget Sound. There was a short-lived but intense fishery for spiny dogfish livers in the 1930s and 1940s. Because researchers had discovered that the livers of spiny dogfish contained high levels of vitamin A, there was a strong demand for use of the liver oils in pharmaceuticals, food processing, and animal feed. Harvests began to decline in 1945 as spiny dogfish abundance declined, and in 1950, the introduction of synthetic vitamins destroyed the market for spiny dogfish livers. Harvests were minimal after the liver fishery ended, and with low catch levels, spiny dogfish abundance increased again by the late 1950s.
New market opportunities for dogfish opened in the 1970s. Europeans have long used spiny dogfish as an inexpensive source of food—fish and chips in particular. The decline of the European dogfish supply provided a market for U.S. fishermen to export their dogfish catch. Also, during the late 1970s, researchers started using shark cartilage in cancer treatment, and a portion of spiny dogfish catches have since been sold for medical research and treatment. However, according to the National Cancer Institute , the cumulative evidence regarding the effectiveness of cartilage as a treatment for people with cancer is inconclusive. There is also a steady market for the educational biological supply market (although with limited growth potential), in which blue and red rubber compounds are injected into the veins and arteries, and the preserved dogfish are then marketed to educational institutions for dissection purposes.
Today, there’s not much consumer demand for spiny dogfish. Off the West Coast and in Alaska, spiny dogfish are mostly caught as bycatch in fisheries for more commercially important species, and many fishermen throw them back because of their low value. Even though harvests are minimal, managers still limit the amount of spiny dogfish that can be harvested as a precaution against overfishing.
LOCATION & HABITAT
Spiny dogfish is one of the most widely distributed sharks that inhabit temperate waters in both the Pacific and the Atlantic Oceans. In the North Pacific, they’re found from the Bering Sea to Baja California. They’re more common off the U.S. West Coast and British Columbia than in the Gulf of Alaska or the Bering Sea and Aleutian Islands region.
Spiny dogfish live in waters as deep as 4,050 feet but most are found in waters less than 1,150 feet deep. Spiny dogfish are common in inland seas, such as San Francisco Bay and Puget Sound, and in shallow bays from Alaska to central California. Males are generally found in shallower water than females, except for pregnant females that enter shallow bays to pup. Immature juveniles live in the water column near the surface. As they grow older, they settle to the bottom.
Dogfish often travel in large schools, largely to protect themselves from predators, and avidly feed during their journeys. The schools include hundreds, if not thousands, of dogfish and tend to divide up according to size and gender, although the young—both male and female—tend to stay together. They can travel far – a spiny dogfish tagged in Queen Charlotte Sound (off British Columbia) was recovered off the northeast coast of Japan years later. Spiny dogfish also migrate seasonally as temperatures change and daily from the bottom during the day to the surface at night.
Spiny dogfish live a long time, sometimes over 80 years. They grow slowly, up to over 4 feet and 22 pounds, although adults are generally 2½ to 3½ feet long. Spiny dogfish aren’t able to reproduce until they’re older – females mature at an average age of 35, males mature at an average age of 19.
Depending on their size, female spiny dogfish have between 2 and 22 eggs each per season. They mate annually, and the eggs are fertilized internally. They develop internally for 22 to 24 months; this is among the longest gestation periods known for sharks. Females generally release their young (between 5 and 15 pups) during the fall in shallow bays. The newborn pups range in length from 8-½ to 12 inches.
Spiny dogfish are opportunistic feeders, eating whatever prey is available. They mainly eat small, schooling pelagic fish such as herring, and small invertebrates, such as shrimp, crab, and squid. Spiny dogfish are preyed upon by larger species of shark including larger spiny dogfish, larger fishes such as cod and hake, seals, and killer whales.
Spiny dogfish are slim with a narrow, pointed snout and distinctive white spots. Their bodies are grey above and white below. True to their name, they have sharp spines in front of each of their two dorsal fins.
Scientists just completed the first ever assessment for the spiny dogfish stock off the West Coast. They used information from trawl surveys conducted by NOAA’s Northwest and Alaska Fisheries Science Centers and from a longline survey conducted by the International Pacific Halibut Commission .
According to the recent stock assessment (2011), the West Coast spiny dogfish stock is well above target population levels.
Spiny dogfish are captured periodically in NOAA Fisheries bottom trawl surveys of Alaskan waters; however, due to the rarity or patchy distribution of catches, the abundance estimates from these surveys are considered unreliable. NOAA Fisheries and the International Pacific Halibut Commission conduct more accurate annual longline surveys in Alaskan waters. The survey indices (which reflect trends in the population, not abundance estimates) show stable population trends. The Bering Sea/Aleutian Islands and Gulf of Alaska Shark complexes are scheduled to be assessed in December 2013.
Spiny dogfish have been subject of electromagnetic field research due to their unique Ampullae of Lorenzini organs, found in other elasmobranchs (sharks, skates, and rays). Ampullae of Lorenzini are organs around the mouth which are filled with fluids that help neurons detect changes in electromagnetic fields generated by movements of prey. Some researchers have also theorized that the bottom-dwelling elasmobranchs use electromagnetic fields generated from changes in sea floor substrate to assist with migration patterns.
Since spiny dogfish have skeletons made of cartilage rather than bone, they have a different mechanism for producing what are referred to as “B” (bone marrow) cells in bony vertebrates. In elasmobranchs, these cells are generated outside the skeleton, instead of in the bone marrow. Studying this phenomenon, as well as dogfish renal glands (which produce certain compounds shown to have some success in combating HIV virus particles and cancer cells) may have value in the development of future biomedical treatment therapies for humans.
Harvesting Spiny Dogfish
Although there was an intense commercial fishery for spiny dogfish in the 1940s and a smaller fishery supplying the European market until recently, spiny dogfish is a low-value species and is mostly taken as bycatch in West Coast–based fisheries targeting other commercially important species.
Dogfish are found throughout the Gulf of Alaska, but there has never been a commercial fishery for this species in Alaskan waters. They’re occasionally caught as bycatch in other fisheries but are usually discarded at sea.
Spiny dogfish are also harvested off the west coast of Canada (British Columbia) – the history of fisheries here generally mirrors the fisheries off the U.S. West Coast. Like the fisheries in U.S. waters, fluctuations in landings in Canada have largely been driven by market forces rather than abundance of the resource.
Who’s in charge? NOAA Fisheries and the North Pacific and Pacific Fishery Management Councils
West Coast: Groundfish Fishery Management Plan
- Part of the “Other Fish” complex, which includes all of the non-flatfish or rockfish species managed under the Groundfish Fishery Management Plan that are not assessed.
- Managers set acceptable catch limits for the “Other Fish” complex and limit the amount of spiny dogfish fishermen can harvest per fishing trip.
- Harvests are carefully monitored in commercial fisheries through the West Coast Observer Program and landing reports.
- Coastwide, depth-based closed areas designed to protect overfished groundfish species
- Part of the Shark Complex.
- Managers set a total allowable catch for stock complexes every year, based on annual stock assessments. Complex catch limits are the sum of the recommended limits for each species in the complex.
There are currently no directed commercial fisheries for shark species in federally or state-managed waters of Alaska. Spiny dogfish are caught incidentally in fisheries for groundfish. Nearly all shark catch is discarded at sea, but some spiny dogfish are retained as incidental catch in state-managed fisheries. A little over 23,000 pounds of spiny dogfish were harvested in Alaska waters in 2011.
Off the West Coast, commercial fishermen brought 1,259,814 pounds of spiny dogfish into port in 2011. The majority of the harvest came from Washington (435,979 pounds) or at-sea-processing vessels (641,034 pounds).
The 2011 landings of Pacific spiny dogfish were valued at more than $200,000; though not in high demand in the United States, spiny dogfish is sometimes a valuable commodity on the global market. Improved marketing within the United States could help stabilize demand, which would in turn provide a financial incentive for regional fisheries to reduce discards of incidentally caught dogfish. Continued development of other niche markets, such as biological supply, could further help provide market-based solutions that would reduce discards.
Spiny dogfish are generally not targeted by anglers off the West Coast or Alaska. However, due to their aggressive feeding nature, they tend to bite baited hooks and are incidentally caught in many recreational fisheries. Off the West Coast, dogfish are considered a bottomfish so they are restricted by the recreational coastwide aggregate limit of 12 per day (although most are released as they’re not highly valued) as well as all other applicable bottomfish recreational restrictions (depth, season, etc.). In Alaska, anglers are limited to retaining 2 sharks of any kind per year.
Caught in fisheries in Canada, Iceland, Norway, the United Kingdom, and the United States, spiny dogfish (which can be either the Atlantic S. acanthias or the Pacific S. suckleyi) has a sweet, mild flavor and a higher oil content than mako or other sharks. It has a flaky yet firm texture. The raw meat is white. The outer flesh can have a reddish color, which turns brown when cooked. The rest of the meat is white when cooked.
Dogfish meat should have a faintly sweet smell, and although a slight metallic odor is acceptable, it should not smell like ammonia. Sharks lack a traditional urinary tract, so they concentrate urea, a waste product, in their blood and excrete it through their skin. As soon as a dogfish is caught, it must be gutted, bled, and chilled. Otherwise, the urea remains in the flesh, and an ammonia smell develops within 24 hours. (Seafood Business, 2011)
Shark is a low-fat source of protein that is high in selenium and vitamins B6 and B12. Shark may contain amounts of methylmercury in excess of the FDA’s recommended limit for nursing moms, moms-to-be, and young children. For more information, see EPA and FDA advice on what you need to know about mercury in fish and shellfish.
|Serving Size||100 g|
|Fat, total||4.51 g|
|Saturated fatty acids, total||0.925 g|
|Sugars, total||0 g|
|Fiber, total Dietary||0 g|
Pacific Spiny Dogfish Table of Nutrition