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Advances in the aquatic sciences
RESEARCH ARTICLE

Increasing codend mesh openings: an appropriate strategy for improving the selectivity of penaeid fishing gears in an Australian estuary?

William G. Macbeth A B D , Matt K. Broadhurst A , Russell B. Millar C and Stephen D. A. Smith B
+ Author Affiliations
- Author Affiliations

A NSW Department of Primary Industries, Fisheries Conservation Technology Unit, National Marine Science Centre, PO Box J321, Coffs Harbour, NSW 2450, Australia.

B School of Environmental Sciences & Natural Resource Management, The University of New England, National Marine Science Centre, PO Box J321, Coffs Harbour, NSW 2450, Australia.

C Department of Statistics, The University of Auckland, Private Bag 92019, Auckland, New Zealand.

D Corresponding author. Email: will.macbeth@dpi.nsw.gov.au

Marine and Freshwater Research 56(6) 889-900 https://doi.org/10.1071/MF04256
Submitted: 11 October 2004  Accepted: 26 May 2005   Published: 27 September 2005

Abstract

This study investigates the effects of increasing the lateral mesh openings in codends on the size and species selectivity of lagoon and river seines and a stow net used to target penaeid prawns (eastern king (Penaeus plebejus), school (Metapenaeus macleayi) and greasyback prawns (M. bennettae)) in Wallis Lake, New South Wales, Australia. Compared with conventional codends made from 36-mm diamond-shaped mesh, new designs made from 25- and 29-mm mesh hung on the bar (i.e. square-shaped mesh) significantly reduced the catches of non-target fish (by between 58 and 95%) and improved size selection for the targeted penaeids in the stow net and lagoon seine. In contrast, owing to gear-specific operational characteristics such as a slower hauling speed, there were few detectable effects of altering mesh openings in the codend of the river seine. The results are discussed in terms of the differences in the gears used and their particular selection mechanisms. We conclude that, pending further trials, codends made from a mesh size approaching 29 mm, hung on the bar, would provide appropriate size- and species-selection for Wallis Lake stow nets and lagoon seines. Further research is required, however, to examine the utility of operational changes to river seines and/or alterations to mesh size and configuration in the wings and body to improve selectivity.

Extra keywords: bycatch, prawn, seine, shrimp, square mesh, stow net.


Acknowledgments

Funding for this work was provided by NSW Department of Primary Industries and the Fisheries Research and Development Corporation (Grant no. 2001/031). Thanks are extended to Michael Wooden, Damian Young, David and Irene Johnson and the commercial estuary penaeid fishers of the Great Lakes region.


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