An Evaluation of Reduced Bar Spacing Turtle Excluder Devices (TED) for the US Shrimp Trawl Fishery

Shrimp is the most valuable internationally traded seafood commodity, and wild caught shrimp make up almost half of the ~6.6 MMT annual global production. In addition to target shrimp catch, tropical shrimp trawling (TST) is also responsible for the capture of one third of the world’s total bycatch, leading many to consider TST to be the most destructive fishing practice in the world. Though the bycatch of large animals can be eliminated by use of turtle excluder devices (TED), this technology remains ineffective at reducing the capture of smaller organisms, which represent a large portion of the bycatch. To further reduce bycatch in the US TST fleet, a variety of Bycatch Reduction Devices (BRD) are currently being used in addition to the TED.  In this study we report on the efficacy of a new TED model to reduce bycatch and maintain target shrimp catch. The new TED model is characterized by 5-cm spacing between flat bars which differs from  the current industry standard of 10-cm spacing between round bars. Comparative towing experiments under standard commercial shrimp trawling operations in waters off of Georgia, Texas and Mississippi during the summer of 2012 indicate shrimp losses or gains of  -3.8%, +5.8%, -2% respectively and an overall reduction in the capture of sharks (52-87.5%), rays (20-80%) and horseshoe crabs (100%). Though these experiments are limited in time and space, and therefore not representative of fishing conditions throughout the year, this study suggests the new TED’s ability to reduce bycatch while maintaining target shrimp catch. These positive results should lead to a broader investigation of the benefits of using reduced spacing flat bar TEDs for the US shrimp trawl industry.