As the coastal and open ocean waters of New England warm in May and June, many species of fish migrate north from their southern wintering grounds - among them the sharks. While most people don't think of Massachusetts when they think of sharks, that doesn't stop the migration of no fewer than a dozen shark species in and out of New England waters annually. Oceanic sharks like the blue, mako, thresher, and basking shark swim onto the continental shelf from offshore capitalizing on the productive northeast waters rich in food and reproductive opportunity. Coastal species like the sandbar shark, spiny and smooth dogfish, dusky, and sand tiger invade nearshore waters. Tropical species, like the tiger and the hammerhead, make an occasional appearance during our warmest months. The porbeagle shark is the only species found year-round in Massachusetts waters because of its preference for colder temperate waters. Although rare, the most notorious of all sharks, the great white shark, is known to visit New England waters, keeping to itself despite its heinous reputation. In fact, Massachusetts represents the northernmost range for several species of sharks. Therefore, it is an important area for monitoring the health and distribution of shark populations.
Science currently recognizes over 360 species of sharks occurring throughout the world, ranging in size from the eight-inch dwarf dogshark to the 60-foot whale shark. Their habitat ranges from coastal areas to the open ocean, from Arctic waters to tropical seas, from surface waters to abyssal depths, and from estuaries to freshwater rivers. Sharks are uniquely distinguished from other fishes by their cartilaginous skeleton, five to seven gill slits, and sandpaper-like scales called denticles. They have evolved over 400 million years and the modern species have changed little since the dinosaurs. The evolutionary success of these animals can be attributed to their unique adaptations. They possess at least six senses finely tuned to navigate, communicate, and detect prey. Their multiple rows of sharp teeth are replaced continually to insure efficiency.
Despite popular belief that sharks will eat anything (including humans), many species are highly selective in their food habits. In general, fishes, mollusks, and crustaceans comprise the bulk of a sharks diet. Most species reproduce as mammals do. Fertilization is internal and gestation ranges from nine months to two years, resulting in the birth of a relatively low number of fully developed baby sharks or 'pups'. Growth rates of sharks are generally very slow compared to other types of fishes with some species growing only inches a year and taking up to 20 years to sexually mature. Sharks are long-lived, with some species reaching ages in excess of 50 years.
Each species of shark is unique and no single life history characteristic (i.e. growth rate, food habits, distribution) can be applied to all shark species. Unfortunately, much of the basic life history research remains to be done. However, those general characteristics, which have allowed shark populations to flourish such as, slow growth, low numbers of young, and late ages of sexual maturity, have rendered them extremely sensitive to fishing pressure. Historically, shark populations have plummeted in the face of intense fishing activities because they cannot replace themselves fast enough to sustain the fishery.
In Massachusetts, there are no directed commercial fisheries for sharks except trawl and gillnet fisheries for spiny dogfish, a small schooling fish weighing less than 10 pounds. Of the 5.7 million pounds of shark landed in the Commonwealth in 2000, 99% were spiny dogfish with a commercial value of $1.3 million. The remaining 1% was primarily makos, threshers, and porbeagles taken incidental to offshore trawl, longline, and gillnet fisheries based in this state.
A substantial recreational fishery for sharks occurs in Massachusetts from June through September each year. Although many Massachusetts recreational fishermen target sharks, most of those caught are released. Not only is the shark an important component of the Massachusetts recreational fishery, but it is currently fished as a sustainable resource.
The National Marine Fisheries Service Fishery Management Plan for sharks of the Atlantic Ocean recommends that states, "actively participate in acquiring pertinent information and data" on sharks. The Massachusetts Shark Research Program (MSRP) was established in 1990 to study the ecology, distribution, and relative abundance of sharks that are subject to recreational fisheries in the Commonwealth. A thorough understanding of these parameters is crucial to the management process and wise utilization of these resources. In addition to fieldwork, the project also provides public education and technical information on the biology, management, and use of sharks. DMF biologists conduct cooperative research with other world-renowned shark researchers to provide local expertise and biological samples for these cosmopolitan, highly migratory predators.
Inshore: From late June through August of each year, MarineFisheries personnel set longlines to sample those species of sharks that enter coastal waters. The inshore areas east and south of Martha's Vineyard are consistently sampled. Sharks are taken on longlines and either tagged with standard NMFS tags and released or sacrificed for life history research. Biologists examine biological parameters including age structure, feeding ecology, local movements, and reproductive status through dissection and tagging of shark specimens. They generate annual catch indices from longline data to monitor trends in the relative abundance of coastal shark species. During this period, surf fishermen that routinely target sharks on the Cape and Islands are surveyed for important information on the species, size, sex, and other details for each shark they land. When compiled, these data help elucidate the ecology of these species in our waters.
Offshore: Anglers participating in offshore fishing tournaments make large pelagic sharks including the blue, mako, and thresher available to the program. In addition, biologists make offshore trips with cooperative fishing vessels and our own research vessel to sample offshore sharks. The collective information that is gathered contributes to our understanding of these elusive predators.
One of the most important aspects of the program is the educational component. Throughout the year, biologists present extensive slide shows to schools, clubs, and conservation groups throughout the Commonwealth on New England sharks, their biology, fisheries, and study. Also, information about sharks is provided to a variety of media interests that include magazines, television, and documentary producers. These efforts educate the public about these remarkable animals that are an integral component of the marine ecosystem.
MarineFisheries biologists routinely sample sharks for other researchers during field activities. Academic scientists, students, public aquariums, conservation groups, and other state and federal agencies are among the groups that have been assisted.