Bycatch Reduction Devices

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Bycatch reduction devices

Seabirds, seals , whales , sea turtles , dolphins , and nontargeted fish can be unintentionally caught and killed or maimed by modern fish and shrimp catching methods. This phenomenon is called "bycatch" or the unintended capture or mortality of living marine resources as a result of fishing. It is managed under such laws as the Migratory Bird Treaty Act, the Endangered Species Act of 1973, the Marine Mammals Protection Act of 1972 (amended in 1994), and, most recently, the Magnuson-Stevens Fishery Conservation and Management Act of 1996. The 1995 United Nations Code of Conduct for Responsible Fisheries, to which the United States is a signatory, also emphasizes the importance of bycatch reduction. Bycatch occurs because most fishing methods are not perfectly "selective," (i.e., they do not catch and retain only the desired size, sex, quality and quantity of target species ). It also occurs because fishermen often have incentive to catch more fish than they will keep.

Although the exact extent of bycatch-related mortality is uncertain, public awareness of the problem has grown in the 1990s, leading to a deepening public perception that commercial fisheries are wasteful of the world's finite marine resources. According to a 1994 estimate of the United Nations' Food and Agriculture Organization, worldwide commercial fishing operations discarded 30 million tons (27 million metric tons) of fish, approximately one-fourth of the world catch, because they were the wrong type, sex, or size. In United States fisheries, a total of 149 species groups have been identified as bycatch, 67% of them finfish, crustaceans, or mollusks, and 37% of them protected marine mammals, turtles, or seabirds.

To address this problem, numerous research programs have been established to develop BRDs and other means to reduce bycatch. Much of this research, and the nation's bycatch reduction activities overall, is centered in the Department of Commerce's National Marine Fisheries Service (NMFS), which leads and coordinates the United States' collaborative efforts to reduce bycatch. In March 1997, NMFS proposed a draft long-term strategy, Managing the Nation's Bycatch, that seeks to provide structure to the service's diverse bycatch-related research and management programs. These include gear research, technology transfer workshops, and the exploration of new management techniques. NMFS's Bycatch Plan was intended to as a guide for its own programs and for its "cooperators" in bycatch reduction, including eight regional fishery management councils, states, three interstate fisheries commissions, the fishing industry, the conservation community, and other parties. In pursuing its mandate of conserving and managing marine resources, NMFS relies on the direction for bycatch established by the 104th Congress under the new National Standard 9 of the Magnuson-Stevens Act, which states: "Conservation and management measures shall, to the extent practicable, (A) minimize bycatch and (B) to the extent bycatch cannot be avoided, minimize the mortality of such bycatch."

But, although the national bycatch standard applies across all regions, bycatch issues are not uniform for all fisheries. Indeed, bycatch is not always a problem and can sometimes be beneficial, (e.g., when bycatch species are kept and used as if they had been targeted species). But where bycatch is a problem, the exact nature of the problem and potential solutions will differ depending on the region and fishery. For instance, in the U.S. Gulf of Mexico shrimp fishery, which contributes about 70% of the annual U.S. domestic shrimp production, bycatch of juvenile red snapper (Lutjanus blackfordi ) by shrimp trawlers reduces red snapper stocks for fishermen who target those fish. According to NMFS, "In the absence of bycatch reduction, red snapper catches will continue to be a fraction of maximum economic or biological yield levels." To address this problem, the Gulf of Mexico Fishery Management Council prepared an amendment to the shrimp fishery management plan for the Gulf of Mexico requiring shrimpers to use BRDs in their nets. But BRD effectiveness differs, and devices often lose significant amounts of shrimp in reducing bycatch. For instance, one device called a "30-mesh fisheye" reduced overall shrimp catches, and revenues, by 3%, an issue that must be addressed in any analysis of the costs and benefits of requiring BRDs, according to NMFS. In Southern New England, the yellowtail flounder (Pleuronectes ferrugineus ) has been important to the New England groundfish fisheries for several decades. But the stock has been depleted to a record low because, from 19881994, most of the catch has been discarded by trawlers. Reasons for treating the catch as bycatch were that most of the fish were either too small for marketing or were smaller than the legal size limit. Among the solutions to this complex problem an increase in the mesh size of nets so smaller fish would not be caught and a redesign of nets to facilitate the escape of undersized yellowtail flounder and other bycatch species.

Although fish bycatch exceeds that of other marine animals, it is by no means the only significant bycatch problem. Sea turtle bycatch has received growing attention in recent years, most notably under the Endangered Species Act Amendments of 1988, which mandated a study of sea turtle conservation and the causes and significance of their mortality, including mortality caused by commercial trawlers. That study, conducted by the National Research Council (NRC), found that shrimp trawls accounted for more deaths of sea turtle juveniles, subadults, and breeders in coastal waters than all other human activities combined. According to the NRC's 1990 report, some 5,00050,000 loggerhead turtles (Caretta caretta ) and 5005,000 Kemp ridleys (Lepidochelys kempi ) a year are killed by shrimping operations from Cape Hatteras, North Carolina, to the Mexican border in the Gulf of Mexico. Deaths from drowning increase when trawlers tow their catch for longer than 60 minutes. Winter flounder trawling north of Cape Hatteras, Chesapeake Bay passive-gear fishing, and other fisheries were also found to be responsible for some turtle mortality.

To address the turtle bycatch problem, NMFS, numerous Sea Grant programs, and the shrimping industry conducted research that led to the development of several types of net installation devices that were called "turtle excluder devices" (TEDs) or "trawler efficiency devices." In 1983, the only TED approved by NMFS was one developed by the service itself. But in the face of industry concerns about using TEDs, the University of Georgia and NMFS tested devices developed by the shrimping industry, resulting in NMFS certification of new TED designs. Each design was intended to divert turtles out of shrimp nets, excluding the turtles from the catch without reducing the shrimp intake. Over a decade of development, these devices have been made lighter and today at least six kinds of TEDs have NMFS's approval. Early in the development of TEDs, NMFS tried to obtain voluntary use of the devices, but shrimpers considered them an expensive, time-consuming nuisance and feared they could reduce the size of shrimp catches. But NMFS, and environmental groups, countered that the best TEDs reduced turtle bycatch by up to 97% with slight or no loss of shrimp. By 1985, NMFS faced threats of lawsuits to shut down the shrimping industry because trawlers were not using TEDs. In response, NMFS convened mediation meetings that included environmentalists and shrimpers. The meetings led to an agreement to pursue a "negotiated rulemaking" to phase in mandatory TED use, but negotiations fell apart after state and federal legislators, under intense pressure, tried to delay implementation of TED rules. After intense controversy, NMFS published regulations June 28, 1987, on the use of TEDs by shrimp trawlers.

Dolphins are another marine animal that has suffered significant mortality levels as a result of bycatch associated with the eastern tropical Pacific Ocean tuna fishery. Several species of tuna are often found together with the most economically important tuna species, the yellowfin (Thunnus albacares ). As a result, tuna fishermen have used a fishing technique--called "dolphin fishing," in which they set their nets around herds of dolphins to capture the tuna that are always close by. The spotted dolphin (Stenella attenuata ) is most frequently associated with tuna. Spinner dolphin (Stenella longirostris ), and the common dolphin (Delphinus delphis ) also travel with tuna. According to one estimate, between 19601972 the U.S. fleet in the eastern tropical Pacific Ocean fishery killed more than 100,000 dolphins a year. That number dropped to an estimated 20,000 after 1972, when the Marine Mammals Protection Act was passed. By 1989, the number was estimated at 12,643, largely because the number of boats in the U.S. tuna fishing fleet declined and those that were in operation killed fewer dolphins. U.S. fishing boats are now required to use techniques that allow dolphins to escape from tuna nets before the catch is hauled in. These include having fishermen jump into the ocean to hold the lip of the net below the water surface so the dolphin can jump out.

[David Clarke ]



Decline of the Sea Turtles, Causes and Prevention. Washington, D.C.: National Academy Press, 1990.

Dolphins and the Tuna Industry. Washington, D.C.: National Academy Press, 1992.

Managing the Nation's Bycatch: Priorities, Programs and Actions for the National Marine Fisheries Service. Washington, D.C.: National Marine Fisheries Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, March 20, 1997.