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RESEARCH ARTICLE
Contents Vol 57(4)

Validating ecological risk assessments for fisheries: assessing the impacts of turtle excluder devices on elasmobranch bycatch populations in an Australian trawl fishery

Shane P. Griffiths A C , David T. Brewer A , Don S. Heales A , David A. Milton A and Ilona C. Stobutzki B
+ Author Affiliations
- Author Affiliations

A CSIRO Marine and Atmospheric Research, PO Box 120, Cleveland, Qld 4163, Australia.

B Bureau of Rural Sciences, GPO Box 858, Canberra ACT 2601, Australia.

C Corresponding author. Email: shane.griffiths@csiro.au

Marine and Freshwater Research 57(4) 395-401 https://doi.org/10.1071/MF05190
Submitted: 21 September 2005  Accepted: 6 April 2006   Published: 14 June 2006

Abstract

Demonstrating ecological sustainability is a challenge for fisheries worldwide, and few methods can quantify fishing impacts on diverse, low value or rare species. The current study employed a widely used ecological risk assessment method and incorporated new data to assess the change in sustainability of species following the introduction of Turtle Excluder Devices (TEDs) in Australia’s Northern Prawn Fishery (NPF). Population recovery ranks changed for 19 of the 56 elasmobranch species after the introduction of TEDs, with nine species showing an increase in sustainability. Unexpectedly, ten species showed a decrease in sustainability. This was due to TEDs successfully excluding large animals from the catch, resulting in a lower mean length at capture, which reduced the recovery ranks for two criteria relying on length data. This falsely indicates that TEDs increase the impact on pre-breeding animals, thus reducing the recovery potential of these species. The results demonstrate that existing attribute-based risk assessment methods may be inadequate for reflecting even the most obvious changes in fishing impacts on bycatch species. Industry and management can benefit greatly from an approach that more accurately estimates absolute risk. The development and requirements of a new quantitative risk assessment method to be developed for the NPF, and applicable to fisheries worldwide, are discussed.

Extra keywords: extinction, fisheries management, prawn, rays, sharks, sustainability, tropical.


Acknowledgments

We thank Alistair Hobday, Steve Blaber and Richard Pillans of CSIRO Marine and Atmospheric Research for critically evaluating drafts of this manuscript. Preparation of this manuscript was funded by the Australian Fisheries Research and Development Corporation (FRDC) (Project no. 2002/035) and utilised data collected in two other FRDC funded projects (96/357 and 2000/173).


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