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RESEARCH ARTICLE
Contents Vol 60(8)

Reducing impacts of trawling on protected sea snakes: by-catch reduction devices improve escapement and survival

David A. Milton A B , Gary C. Fry A and Quinton Dell A
+ Author Affiliations
- Author Affiliations

A Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, PO Box 120, Cleveland, Qld 4163, Australia.

B Corresponding author. Email: david.milton@csiro.au

Marine and Freshwater Research 60(8) 824-832 https://doi.org/10.1071/MF08221
Submitted: 29 July 2008  Accepted: 20 February 2009   Published: 27 August 2009

Abstract

Sea snakes (Hydrophidae) are by-catch of prawn trawling throughout the tropical Indo-western Pacific. We tested the effectiveness of three by-catch reduction device (BRD) types set at different distances from the codend in Australia’s Northern Prawn Fishery (NPF). Trained crew-member observers compared the numbers of sea snakes caught in paired Control and Treatment nets in 1365 trawls. Catches of sea snakes were reduced by 43% on those vessels where a Fisheye BRD was positioned less than 70 meshes from the codend. A separate study with a scientific observer undertook trials with a ‘popeye’ Fishbox BRD. This BRD reduced sea snake catch by 85% and small fish by-catch by 48%. Catches of target prawn were similar for all nets in both studies (difference <2%). Adoption of the more effective BRDs (‘popeye’ Fishbox or Fisheye BRDs) by the NPF and locating them within 70 meshes of the codend can potentially reduce sea snake catch and thus their mortality from ~7000 in the 2007 fishing season to as few as 1500 snakes. Our study shows that the use of BRDs in tropical coastal demersal fisheries and positioning them closer to the codend will greatly reduce the catch of vulnerable sea snakes.

Additional keywords: management, mitigation, prawn trawling, survival.


Acknowledgements

We thank all the crew member observers who participated in the program. We especially thank Jim Yarrow for his innovation to develop and trial new BRDs during his commercial fishing. We thank Don Heales and Ted Wassenberg and two anonymous referees for constructive comments on earlier versions of the manuscript. The project was jointly funded by the Fisheries Research and Development Corporation (Project 2005/051) and CSIRO.


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