Reducing Elasmobranch Bycatch in the Atlantic Seabob (Xiphopenaeus kroyeri) Trawl Fishery of Guyana

Abstract

The Atlantic seabob (Xiphopenaeus kroyeri) trawl fishery is very important to Guyana, with 88 licensed industrial vessels harvesting about 15,000 mt annually, representing Guyana's most valuable seafood export. All vessels are already using both teleost by-catch reduction devices (BRDs) and turtle excluder devices (TEDs) to satisfy international market standards. However, the key stakeholder, the Guyana Association of Private Trawler Owners and Seafood Processors, is now seeking to access sustainable seafood markets through pursuing Marine Stewardship Council (MSC) certification. To this end, this study documents elasmobranch by-catch in the current fishery and examines the effectiveness of a modified TED (with a reduced bar spacing and the addition of a brace bar) in reducing elasmobranch by-catch. From July-August 2014, 131 tows were mode, 80 of which represented simultaneous hauls with control and modified TEDs. One shark and 8 ray species were recorded. A statistically significant 40% decline in the elasmobranch catch rate was observed when using modified TEDs compared with control TEDs (mean by-catch rate dropped from 2.3 to 1.4 individuals per twin-trawl/h). Furthermore, modified TEDs significantly reduced the mean size of rays caught by 6.3%. This also resulted in a virtual elimination of 3 IUCN-designated 'Near Threatened' ray species in the by-catch, although having little effect on the copture of small-sized elasmobranch species, including the 'Critically Endangered' Caribbean Electric Roy (Narcine bancroftii). We conclude that the modified TED was successful in reducing the by-catch of vulnerable elasmobranch species and should advance progress towards attaining by-catch standards required for MSC certification.