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 the resource continues to be in good condition, with spiny dogfish not overfished and not experiencing overfishing. Spawning stock biomass is estimated to be 106% of the target. The assessment time period is 2013-2015, however, 2014 survey data points are not included in the assessment because important spiny dogfish areas were skipped by the Northeast Fisheries Science Center’s (NEFSC) Bigelow Trawl Survey in 2014 due to a mechanical breakdown. The Mid-Atlantic Fishery Management Council’s (MAFMC) Science and Statistical Committee (SSC) evaluated several options to address the missing 2014 data, and applied a Kalman Filter for the update, which provides the most stable estimates of survey abundance. Since 2012, survey indices have been declining, largely due to a 2012 data point that is considered ‘very above average’ compared to the ‘near average’ 2013 data point and the ‘below average’ 2015 data point.
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 (Addendum I - V).
Addendum I (2005) provides the Board the flexibility to establish spiny dogfish specifications for up to five years. Addendum II (2008) established regional quotas. Addendum III (2011) set state-specific shares for New York through North Carolina and granted those states flexibility in implementing possession limits and transferring quota. Addendum IV (2012) addressed the differences in the overfishing definitions between the NEFMC, MAFMC and ASMFC. Addendum V (2014) 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 2017 fishing season commercial quota of 39.1 million pounds. Although this represents a significant reduction in quota from 2015, commercial landings have been less than half of the commercial quota for the last several seasons, and the fishery will likely underutilize the quota again. 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 (2.7%); 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.