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, the longest of any vertebrate, 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. The 2014/2015 quota is 49.37 million pounds and the 2015/1016 quota is 50.61 million pounds.
The 2013 stock assessment update, conducted by the Northeast Fisheries Science Center, estimates spiny dogfish are not overfished and not experiencing overfishing. Spawning stock biomass (SSB) was estimated at 465.99 million pounds in 2013 and has exceeded the target (351.23 million pounds) for the past six years. Fishing mortality was estimated to be 0.15 in 2012, well below the plan’s threshold (0.2439). The recommendation from the MAFMC Science and Statistical Committee (SSC) took into account the projected record low recruitment from 1997 to 2003; the recommended quotas are not expected to cause SSB to decline below the biomass threshold.
Discards have remained relatively stable around 11 million pounds over the past decade and are expected to remain near that level in the future fishing seasons. 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.
Spiny dogfish captured as part of the NEAMAP SNE/MA Nearshore Trawl Survey; biological information will be collected on these specimens for use in stock assessments. Photo credit: NEAMAP.
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 October 2013, the Commission's Spiny Dogfish and Coastal Sharks Management Board increased its spiny dogfish quotas for the 2014/15 and 2015/16 fishing seasons (May 1 – April 30) in response to increases in spawning stock biomass. The 2014/2015 quota is now set at 49,037,000 pounds (previously 41,784,000 pounds) and the 2015/1016 quota is set at 50,612,000 pounds (previously 41,578,000 pounds), with a maximum possession limit of 4,000 pounds per day for the northern region states (Maine through Connecticut). The quota is subdivided into a northern region (Maine - Connecticut) share of 58% and state-specific shares for the southern region, 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.