Diamondback terrapins, the only turtle in the US to live in brackish waters, were heavily harvested in the late 1880s to early 1900s and are now under pressure by human development and activities on their habitat and nesting areas. A common threat to terrapin populations along the coast is drowning in crab pots, which they may enter for food or shelter. The Diamondback Terrapin is listed as "Vulnerable” on the IUCN Red List of Threatened Species and the Virginia Department of Wildlife Resources (DWR) lists them as a “Very High Conservation Need".
A terrapin excluder device (TED) is a rigid rectangular device, often made of bright orange plastic, fitted to the entrance funnel of a crab pot that blue crabs can enter through but most terrapins cannot. Some studies have shown that installing TEDs can reduce terrapin bycatch by as much as 80%
For installation instructions, see this video from the National Aquarium in Maryland.