A turtle excluder device (TED) is a specialized device that allows a captured sea turtle to escape when caught in a fisherman's net. A TED is a grid, made of metal bars, that is fit into a trawl net. Small animals, such as shrimp, pass through the grid into the mesh bag at the end of the trawl and are caught. When larger animals, such as sea turtles, sharks, and stingrays, enter the trawl net, they are stopped by the TED and are able to exit through an opening either at the top or bottom of the net.

TEDs were first introduced in the 1970s, mainly through the efforts of NOAA Fisheries. Following 30 years of mandatory use of TEDs throughout the shrimp fishing industry, gear improvements are being introduced almost yearly.

This video here shows a TED works in practice:
videos.fisheries.noaa.gov/detail/video/3828026198001/b-roll:-turtle-excluder-devices