Operational Feasibility of Turtle Excluder Device Use in the Southeastern U.S. Commercial Skimmer Trawl Shrimp Fishery

Skimmer trawls are utilized throughout the southeastern United States to target penaeid shrimp (Penaeidae).  Skimmer trawls consist of nets attached to rigid frames on each side of the vessel that are pushed through the water column.  Once the frames and nets are lowered into the water, only the cod ends are retrieved to remove the catch, while the mouths of the skimmer trawls continually fish.  Because the cod ends can be readily retrieved, skimmer trawls are allowed to utilize restricted tow times (55 and 75 minute, seasonally) in lieu of TED requirements as a sea turtle bycatch mitigation measure.  However, observations aboard commercial vessels indicate that tow times are often exceeded (Scott-Denton et al. 2006).  Recently, a mass stranding event occurring in the late spring 2010 along the Mississippi Gulf Coast was attributed to skimmer trawl activity.  To address this potential problem, the NMFS SEFSC Harvesting Systems Unit investigated the feasibility of TED use in these fisheries.  Utilizing multiple commercial vessels, paired comparisons designed to examine target shrimp catch retention, bycatch reduction and gear usability associated with TED use were conducted.  During testing, a TED was installed in one net, while the other was left naked (no TED installed) with the TED switched between nets daily to remove potential vessel side bias.  Various TED configurations were tested in Mississippi, Alabama (2008 and 2009) and North Carolina (2010).  Results from these studies indicate that TEDs can function effectively in commercial skimmer trawl operations with a relatively minimal reduction in target shrimp catch, which ranged from 0.5% to 11%.  In addition, unwanted bycatch (e.g., sharks, skates, rays) was reduced by approximately 35%.  Also, three sea turtles were observed in control nets during the study, while none were observed in trawls equipped with TEDs.  Results of the study indicate that TEDs are a viable management option for the reduction of sea turtle bycatch in skimmer trawls.  More testing is slated for North Carolina and Louisiana during the 2011 shrimp season.