Small Modifications to Turtle Excluder Devices Have Big Impacts for Gulf Sea Turtles

A recently completed project successfully developed and tested new turtle excluder devices with narrower bar spacing. These devices were found to effectively reduce juvenile sea turtle bycatch while causing no significant decrease in shrimp catch. As a result, a follow-up project aims to encourage the voluntary use of these new devices among shrimpers.

For decades, Turtle Excluder Devices -a grid of metal bars that fit into a trawl net -have been highly successful at helping sea turtles escape after being unintentionally caught in shrimp trawl gear. Over time, TED designs have evolved to address the specific needs of a geographic area or type of trawl net. In the northern Gulf of America (formerly the Gulf of Mexico), NOAA's observer program documented that small juvenile sea turtles commonly found in the area were small enough to slip through the standard-sized TED bars. They lacked the strength to escape.

To tackle this challenge, the Deepwater Horizon Open Ocean Trustee Implementation Group , in collaboration with the otter trawl shrimp fishery, launched a project in the Gulf of America. Their goal: find a way for shrimpers to continue their work and maintain catch levels while giving young turtles a better chance to survive. This effort is part of ongoing work to restore marine species affected by the Deepwater Horizon oil spill .

The project team collaborated with the otter trawl shrimp fishery from the very beginning. They held public meetings in each Gulf state to introduce the project and gather initial feedback from shrimpers. To ensure continuous and more in-depth input, the team created a stakeholder working group. This group, made up of experienced shrimpers from each Gulf state, provided essential feedback on:

• Proposed TED designs
• Selection of TEDs to be tested based on regional usage
• Overall project direction

Gary Graham, a member of the stakeholder working group, reflected on his involvement. "I'm fishing a resource, a public resource, and I try to be as responsible about that as I can be. I've spent most of my career trying to make things better… We've done a lot of things to try to be more sustainable and do the right thing. I think that's our responsibility."

The project team used an established, rigorous system to test modified TEDs with a 2.5-inch bar spacing, narrower than the traditional 4 inches. They first tested seven designs, varying in shape and angle, to determine whether the new TEDs excluded small sea turtles and retained total shrimp catch. Following these initial tests, they evaluated two prototypes on a commercial vessel. The key question was whether the smaller opening could help young turtles escape more effectively without reducing the amount of shrimp caught.

The final evaluations showed clear success, as documented in recently released final reports . The project found that not only does this modified design reduce juvenile sea turtle bycatch, but it also causes no significant decrease in shrimp catch.

Once testing was complete, the project team re-engaged with shrimpers across the Gulf to share the results. This outreach identified shrimp vessel owners interested in testing these smaller bar-spaced TEDs in their own commercial operations. Across 10 meetings, 90 percent of shrimpers said they would be willing to use these modified TEDs. Graham said, "if that smaller grid size can help reduce the bycatch, I'm all in favor of it."

Building on this success, the Open Ocean Trustee Implementation Group recently announced an additional project to reduce juvenile sea turtle bycatch as part of their fourth restoration plan . This will allow the tested TED configurations to be made available for shrimpers who would like to voluntarily use the small-bar TEDs on their vessels.