Spiny dogfish captured as off of Morehead City, NC as part of a feeding study. Photo credit: Chuck Bangley, East Carolina University.
Spiny dogfish (Squalus acanthias) are a small shark species that inhabit both sides of the North Atlantic and North Pacific Oceans, mostly in the temperate and subarctic areas. In the Northwest Atlantic, the stock ranges from Labrador to Florida, and is most abundant from Nova Scotia to Cape Hatteras. Spiny dogfish migrate north in the spring and summer and south in the fall and winter. In the winter and spring, they congregate primarily in Mid-Atlantic waters but also extend onto the shelf break of southern Georges Bank. In the summer, they are located farther north in Canadian waters and move inshore into bays and estuaries. By autumn, dogfish have migrated north with high concentrations in Southern New England, on Georges Bank, and in the Gulf of Maine. They remain in northern waters throughout autumn until water temperatures begin to cool and then return to the Mid-Atlantic.
Juvenile spiny dogfish school by size until sexually mature and then aggregate by both size and sex. Female dogfish reach sexual maturity at 12 years (~29.5 inches), while males reach sexual maturity at six years (~23.6 inches). Mating occurs in the winter months and the pups are delivered on the offshore wintering grounds. Females give birth every two years with litters ranging from two to 15 pups. While carrying one litter, the female will begin developing eggs for the fertilization of her next litter. After an 18 to 24 month gestation period, pups are released live and fully formed at about 14 inches.
Prior to the Fishery Conservation and Management Act of 1976 (now known as the Magnuson-Stevens Reauthorization Act), foreign fleets caught the majority of dogfish in U.S. waters but U.S. fishermen have had uncontested access ever since the Act's passage. The National Marine Fisheries Service (NMFS) encouraged commercial fishermen to target the bountiful stocks of spiny dogfish in the 1980s and 1990s when stocks of other commercially valuable fish in the Northeast declined. Then in 1998, NMFS determined that spiny dogfish were overfished and implemented stringent harvest restrictions in federal waters to allow the stock to rebound. The states followed shortly after with complementary regulations for state waters. Today, commercial fishermen catch spiny dogfish using longlines, trawls, and purse seines. Fishermen target female dogfish because the females grow larger than males and tend to school together. Processors prefer the larger dogfish because they are easier to hold and cut. The commercial fishery supplies the European food fish markets that use dogfish "belly flaps" for fish and chips in England and as a popular beer garden snack called shillerlocken in Germany.
There is also a small scientific fishery in Maine, which uses spiny dogfish to study several of the species' unique biological characteristics. Dogfish have an organ called a rectal gland whose study helps scientists better understand the function of human kidneys. They also secrete a molecule called squalamine, which has strong antibiotic characteristics and shows promise as an anticancer agent.
Landings were approximately 37.2 million pounds in 1992, gradually increasing to a peak of about 60 million pounds in 1996. In the late 1990s, landings declined to an average of around 40 million. After federal and state regulations were implemented in the early 2000s, landings declined to less than five million pounds in 2001 and 2002. They then ranged between two and eight million pounds between 2003 and 2009. As the stock began to improve, landings were increased to 21 million pounds in 2011. Commercial landings continue to be mostly female dogfish, with female landings comprising about 98% of the total commercial catch.
In 2017, commercial landings were estimated at 17.8 million pounds, while recreational harvest was estimated at 313,661 pounds. Discards have remained fairly stable, around 11 million pounds over the past decade and are expected to remain near that level in the future. Canadian and foreign landings have also decreased significantly in recent years. It is anticipated the Canadian dogfish harvest will not increase in the near future given the lack of demand for the product and the subsequent closure of Canadian spiny dogfish processors.
The 2018 Stock Assessment Update indicates the population is not overfished nor experiencing overfishing. The spawning stock biomass estimate of 235 million pounds is slightly above the SSB threshold of 175 million pounds, while the fishing mortality estimate (0.202) is just below the fishing mortality threshold (0.2439). Despite remaining above the threshold, biomass has declined in recent years, requiring a significant reduction in 2019-2020 to ensure that overfishing does not occur.
The next benchmark stock assessment is currently scheduled for completion in 2021.
In 1998, NMFS declared spiny dogfish overfished and initiated the development of a joint fishery management plan (FMP) between MAFMC and the New England Fishery Management Council (NEFMC) in 1999. The Commission approved an Interstate FMP to complement the federal plan in 2003. Both the Commission and federal plans use a fishing mortality rate to set annual quotas and trip limits. The Commission's FMP has an additional five addenda (Addenda I - V).
The spiny dogfish fishery, which operates from May 1 through April 30, is managed though an annual commercial quota, which is further allocated by state shares. Maine through Connecticut receive 58% of the quota and are limited by a maximum possession limit of 6,000 pounds per day. The southern state shares are allocated as follows: New York (2.7%); New Jersey (7.6%); Delaware (0.9%); Maryland (5.9%); Virginia (10.8%); and North Carolina (14.0%). Any overages from the previous fishing seasons are paid back by the region or state in the following season.
In October 2018, the Spiny Dogfish Management Board approved the following commercial quotas for the 2019-2021 fishing seasons:
The quotas are based on the 2018 Stock Assessment Update, which indicates that while the population is not overfished and overfishing is not occurring, biomass has declined, requiring an approximate 46% reduction in the 2019-2020 quota to ensure that overfishing does not occur.