The AusTED II, an improved trawl efficiency device 2. Commercial performance

An Australian-designed bycatch reduction device (BRD), known as the AusTED, was modified to improve its efficiency and simplify its design. The modified version (the AusTED II) was tested under a range of conditions typical of prawn trawl fisheries of north eastern Australia. Trials occurred during commercial trawling operations to heighten industry awareness of research into BRDs and improve the credibility of research results to industry. Average bycatch reduction ranged between 15%? and 49% depending upon fishery conditions, and the capture of large animals such as stingrays and sea turtles was significantly reduced. The AusTED II had a variable effect on prawn catches depending on trawling, conditions, ranging from no significant difference to a 36% loss. The AusTED II offers commercial fishers the benefits of large animal exclusion plus reduced bycatch. Reductions in bycatch were explained in part by the exclusion of fish species with "fusiform" and "laterally compressed" body-forms. Unexpectedly, "weak swimming fish" were also excluded consistently by the AusTED II. The trialing of a single BRD across a range of trawling conditions in north eastern Australia demonstrated the variability in BRD performance that can be attributed mainly to the quantity and composition of bycatch species. It is highly likely that other exclusion systems like the AusTED II will not be immediately suitable to all north east Australian trawl fisheries. The acceptance of BRDs by the Australian trawling industry will depend upon efficient and pragmatic designs coupled with industry confidence in research results. (C) 1999 Elsevier Science B.V. All rights reserved.