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 2015, commercial landings were estimated at 19.1 million pounds, while recreational harvest was estimated at 86,832 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 revised 2015 stock assessment update indicates spiny dogfish are not overfished and not experiencing overfishing. Spawning stock biomass is estimated to be at 106% of the target. The assessment time period is 2013-2015, however the survey data from 2014 was not included in the 2015 update due to a mechanical breakdown in the NEFSC trawl survey. In order to overcome the 2014 data gap, the Mid-Atlantic Council’s Science and Statistical Committee applied a Kalman Filter for the update. This was the best approach because it provided the most stable estimates of survey abundance and hence catch advice.
In 1998, NMFS declared spiny dogfish overfished and initiated the development of a joint fishery management plan (FMP) between the Mid-Atlantic (MAFMC) and New England Fishery Management Councils (NEFMC) in 1999. The Commission began development of an interstate FMP to complement the federal plan in 1999. The Interstate FMP was approved in late 2003 and implemented for the 2003-2004 fishing year. Both the Commission and federal plans use a fishing mortality rate to set annual quotas and trip limits but there are a few differences between the federal and interstate management programs. The Commission's FMP has an addition four addenda (Addendum I - IV).
In 2014, the Board approved Addendum V, which ensures consistency in spiny dogfish management with the Shark Conservation Act of 2010 by prohibiting processing at-sea, including the removal of fins. Prior to approval, states could process spiny dogfish at-sea, so long as the ratio of fins aboard the vessel did not exceed 5% of the ratio of carcasses aboard the vessel.
The spiny dogfish fishing season is from May 1 through April 30. The Board approved a 2016 fishing season commercial quota of 40,360,761 pounds. Although this represents a 20% reduction in quota from 2015 to 2016, landings have been below 24 million pounds for the last two full fishing years. The quota is allocated by state shares, Maine through Connecticut receive 58% and are limited by a maximum possession limit of 5,000 pounds per day. The southern state shares are allocated as follows New York (2.707%); New Jersey (7.644%); Delaware (0.896%); Maryland (5.92%); Virginia (10.795%; and North Carolina (14.036%). Any overages from the previous fishing seasons will be paid back by the region or state in the following season, as has been done in the past.