Turtle Excluder Device

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Turtle excluder device

Sea turtles of several species are often accidentally caught in a variety of fishing gear in many areas of the world, including the southwest Atlantic and the shallow waters of the Gulf of Mexico. Up to 12,500 turtles died annually as a result of entanglement in shrimp trawl fishery alone. It became a concern for the commercial fishing industry and environmentalists alike since almost all sea turtles are endangered, and the turtle excluder device (TED) was developed in the mid-1980s in an effort to prevent turtles from entering nets designed to catch other marine animals.

Turtle excluder device (TED) designs began as barrier nets preventing turtles from being caught in the main net, then modified to gate-like attachments. Three main within-net designs are currently used. The model designed by the National Marine Fisheries Service (NMFS) consists of an addition in the throat of the trawl net, where the diameter narrows toward the end where the catch is held. The addition includes a diagonal deflator grid, that, once encountered by a turtle, forces the animal upwards and out through a door in the top of the net. The trap door is called a by-catch reduction device or BRD. A second grid deflects other fish out another BRD in the side of the net. Several other TEDs are approved that are lighter and less expensive than the NMFS design, all designed to eject turtles and other by-catch through either the top or bottom of the net. Few shrimp are lost in this process, while the capture of turtles and other by-catch is reduced significantly.

Although TEDs are required by law on Mexican shrimp fleets in the Pacific and the Gulf of Mexico, convincing United States fishing boats to adopt their use has been a struggle. A law mandating the use of TEDs on shrimp trawlers operating between March 1 and November 30 was to have gone into effect in 1988, but the State of Louisiana obtained an injunction against the order. Continued challenges brought by Louisiana and Florida, as well as political lobbying and civil disobedience in the fishing community, delayed implementation even further. In March 1993 the final United States regulations were announced, making TEDs mandatory in inshore waters, and in all waters by December 1994. TEDS became mandatory for Australian prawn trawlers in 2000, and tests conducted in 2001 show that bycatch is reduced by more than 90%. An unforeseen financial advantage was obtained by the use of TEDs in the Australian prawn industry because the devices are believed to reduce physical damage to the prawns from larger, heavier animals that crush the catch during capture and sorting. Even with the required TEDs, some 50,000 turtles are caught annually during shrimp trawling.

[David A. Duffus and Marie H. Bundy ]

RESOURCES

BOOKS

Hillestad, H. O., et al. "Worldwide Incidental Capture of Sea Turtles." In Biology and Conservation of Sea Turtles, edited by K. A. Bjorndal. Washington, DC: Smithsonian Institution Press, 1981.

Seidel, W. O. and C. McVea. "Development of a Sea Turtle Excluder Shrimp Trawl in the Southeast U.S. Penaeid Shrimp Trawl." In Biology and Conservation of Sea Turtles, edited by K. A. Bjorndal. Washington, DC: Smithsonian Institution Press, 1981.