Broadhurst and Kennelly: Composite square-mesh panel in codends for reducing bycatch in an Australian prawn-trawl fishery 
663 
Given the physical profile of these individuals and 
their large size, it is unlikely that once captured by 
the trawl, they would have been able to fit through 
the small square-meshes of the composite-panel. In 
a previous study (Broadhurst and Kennelly, 1996), 
we showed that large quantities of small individuals 
of long spined flathead, Platycephalus longispinis, 
escaped through the square-meshes in the compos- 
ite-panel (62% reduction compared with a conven- 
tional codend). Because the tiger and eastern blue 
spot flathead captured in the present study are physi- 
cally similar to this species, it may be possible to fa- 
cilitate their escape simply by increasing the size of 
mesh in the panel (assuming they display similar 
responses to stimuli from the trawl). Such a modifi- 
cation, however, would likely result in less retention 
of smaller individuals of commercially important 
species such as red spot and stout whiting (see Figs. 
5 and 6, A-B), cuttlefish, and southern calamari. In 
addition, the composite-panel has been designed so 
that the load is distributed across the many bars of 
the 40-mm square-shaped mesh. Any major increase 
in this mesh size would result in the distribution of 
load across fewer bars, possibly altering the geometry 
of the codend and its overall performance. 
In the present study, we have shown that the com- 
posite-panel codend consistently increased catches 
of prawns over a range of operational conditions while 
removing large quantities of unwanted bycatch 
throughout the entire geographic range of the NSW 
oceanic prawn-trawl fishery. In another study in 
Australia, Robins-Troeger et al. (1995) tested a large 
and comparatively complex BRB (termed the 
“AusTED”) off northern Australia and, despite re- 
ports of significant losses of prawns, concluded that 
“the AusTEB system has the potential to be devel- 
oped to suit trawling conditions encountered in dif- 
ferent Australian prawn fisheries.” It is unlikely, 
however, that any design of a BRB would be accepted 
and endorsed by fishermen if it did not consistently 
maintain catches of the target species throughout the 
range of the fishery — as is shown to be the case in 
the present paper for the composite-panel codend (see 
also Kendall, 1990; Renaud et al., 1992). 
In terms of promoting a large-scale voluntary adop- 
tion of BRB’s, like the composite-panel described in 
the present paper, it is useful to provide industry 
not only with evidence of catch rates similar to those 
obtained with conventional gear but also with evi- 
dence of additional benefits, such as a potential for 
increasing duration of tows, improving quality of 
catches (due to less damage from bycatch in the 
codend), increasing savings in labor and fuel, reduc- 
ing sorting times, and reducing conflicts with other 
user groups (e.g. recreational and commercial fish- 
ermen targeting stocks of bycatch species). The real- 
ization of these incentives, along with the results from 
the present study, have resulted in many commercial 
fishermen using the composite-panel throughout the 
entire NSW oceanic prawn -trawl fishery. 
Acknowledgments 
This work was funded by the Australian Fishing In- 
dustry Research and Bevelopment Corporation 
(Grant No. 93/180). The authors are grateful to Gerry 
O’Boherty for his valuable expertise and assistance 
in the field, Tommy Richardson, Barry Williams, 
Buck Anderson, and Sparrow Castle for the use of 
their respective vessels, and to Chris Paterson for 
providing technical support. 
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