Turtle excluder device

A typical TED is a rigid or semi-rigid grid mounted inside a trawl net, with an escape opening covered by a flap that helps retain the target catch. Small animals such as shrimp pass through the bars toward the cod end, the rear portion of the net where catch accumulates. A larger animal encountering the grid is deflected toward the escape opening and can leave the net. Designs vary in grid angle, bar spacing, opening position and materials; these details affect which animals are excluded and how well the target catch is retained.

In the southeastern United States, efforts to reduce sea-turtle captures in shrimp trawls began in the 1970s. Early webbing-panel approaches had limited turtle-exclusion performance or substantial shrimp loss and could clog. Later designs placed a rigid grid inside the net, separating larger animals after they entered the trawl. NOAA Fisheries describes tests of early grid prototypes and subsequent refinements, including top-opening designs, which improved turtle escape while retaining shrimp. The agency's historical account records final federal regulations requiring TED use in parts of the U.S. shrimp fishery in 1987, followed by broader requirements in 1989.

TEDs address bycatch: the unintended capture of animals during fishing. NOAA Fisheries reports that current designs are determined to be 97% effective at excluding turtles from shrimp trawls, while emphasizing continued equipment development. The result should not be read as a guarantee for every device or fishing condition. A study of Australia's northern prawn-trawl fishery found that paired nets fitted with both TEDs and bycatch-reduction devices caught fewer turtles and several other non-target groups, with some reduction in prawn catch; because the treatment combined devices, those results cannot be attributed to TEDs alone. Performance can differ by fishery, species, gear setup and operation.

Requirements are fishery- and jurisdiction-specific rather than universal. In the United States, NOAA Fisheries describes TED requirements for specified shrimp and summer-flounder trawl fisheries in the southeastern region. Its historical record also documents continued modifications to improve performance and accommodate varied vessels and catch conditions. Proper installation and adherence to applicable rules are essential: a grid or escape opening that is damaged, obstructed or incorrectly fitted may not perform as designed.