The effect of prawn trawling continues to be raised by many stakeholders and management agencies as a major problem for sea turtle conservation. In recent years, several developments have reflected these concerns such as the Endangered Species Protection Act (ESPA), the embargo by the United States of America on prawn imports from countries without appropriate turtle bycatch management plans and measures, the public nomination of prawn trawling as a Key Threatening Process under the Endangered Species Protection Act , and the Great Barrier Reef Marine Park Authority’s (GBRMPA) submission to the Queensland Fisheries Management Authority (QFMA).
NORMAC/AFMA needs to have an accurate estimate of catch and mortality of turtles in the NPF to be able to address concerns and, develop and evaluate the effectiveness of management measures to reduce the bycatch of turtles eg. effort adjustments, introduction of bycatch reduction devices (BRDs). With significant changes to the NPF since 1989/90, there is now a need for further information on the species composition, catch and mortality of turtles in the Northern Prawn Fishery (NPF). There is also a need for critical data for the design of a cost-effective logbook based turtle bycatch monitoring program in the NPF and method of assessing the effect of prawn trawling on turtle bycatch species that are acceptable to all stakeholders.
The data produced by this project will be used to :
1. independently verify the logbook records of turtle catches,
2. measure the impact on turtle populations of the 1988/92 fleet restructure,
3. provide a baseline to measure the impact of the effort adjustment package proposed for 1999,
4. provide information to assess the introduction of bycatch reduction devices (BRDs) into the fishery and,
5. further the understanding of the biology and movements of turtles in the fishery.
A successful verified logbook system for ongoing monitoring of turtle catches that is acceptable to most stakeholders is likely to have application to similar species of concern in other fisheries.
Final report
Bycatch, the catch of non-target species, is a significant issue in many of the world's fisheries. Sea turtles are of particular concern given their endangered status and the considerable numbers caught, and occasionally killed, worldwide in commercial fishery operations. Trawl fisheries, in particular, are recognised as discarding the greatest amount of bycatch compared to other commercial fishing methods. An estimated 37.2% of the total global discards have been attributed to trawlers (Alverson et al., 1994). In addition, trawling operations have been held responsible for more sea turtle deaths than any other human-related factor (Bisong, 2000). A project conducted in 1989 and 1990 estimated 5 000 to 6 000 turtles were caught by NPF trawlers annually, with a mortality rate of up to 39% (Poiner and Harris, 1996).
For many years Turtle Excluder Devices (TEDs) have been hailed as the solution to sea turtle mortality from trawl fisheries. TEDs - devices sewn into trawl nets that selectively remove large organisms, such as turtles, while allowing the smaller target species to be caught - have been introduced in many trawl fisheries worldwide. In 2000, the use of TEDs was made mandatory in the NPF.
This study evaluates the effectiveness of TEDs in reducing sea turtle bycatch in the NPF.
