All sea turtles found in U.S. waters are listed under the Endangered Species Act as either threatened or endangered. NOAA Fisheries evaluates, researches, and addresses bycatch of sea turtles in trawl gear used in the Gulf of Mexico and Atlantic Ocean through:
- developing bycatch estimates;
- studying sea turtle ecology and fishery interactions;
- regulating certain fisheries to reduce sea turtle bycatch;
- discussing mitigation options with the fishing industry and others; and
- researching gear and operational measures to reduce the severity of interactions that do occur.
In the 1970s, incidental bycatch of sea turtles in shrimp trawling gear in the southeastern U.S. was determined to be a major threat to the survival of sea turtle populations. NOAA Fisheries’ Southeast Fisheries Science Center Gear Research Branch, with assistance from the commercial shrimping industry, initiated research to develop solutions to this problem. The result of over a decade of gear development, and subsequent evaluation, was the turtle excluder device (TED) followed by federal regulations requiring widespread use beginning in 1989.
The modern TED is a simple 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 like sea turtles enter the trawl net, they are redirected by the TED and are able to exit through an opening either at the top or bottom of the net. Current TED designs have been determined to be 97 percent effective in excluding turtles from shrimp trawls. NOAA Fisheries gear experts continue to work with the shrimp fishing industry to develop new and effective ways to reduce bycatch.
Today, many shrimp trawlers operating in the U.S. waters of the Gulf of Mexico and South Atlantic are required by federal law to equip their trawls with a TED. This widespread use has helped sea turtle populations increase over the last several decades. But there is still work to be done. Sea turtles still interact with shrimp trawls but since most turtles escape through the TEDs, documenting the number of interactions is difficult. As trawling usually occurs at night and in murky water, camera systems have proven inconsistent in detecting sea turtle interactions with trawls. Recently while observing wild turtle interactions with TEDs it was discovered that sea turtles make a distinct acoustic sound when their shell (carapace) contacts the metal bars of the TED. This acoustic signal is different from that of other marine life due to their hard shell. With the advent of Machine Learning (ML) and Artificial Intelligence (AI), we want to explore the potential to use acoustics to detect sea turtle interactions in shrimp trawls.
We are seeking an intern to assist with this project by analyzing video and acoustic data from trawl surveys conducted in 2022 and 2023. During these surveys, nearly 700 sea turtles were encountered and documented using video and acoustic recorders, and we anticipate additional data will be collected in the spring of 2024. If the intern is interested, there may also be opportunities to participate in short-duration sea turtle fieldwork.