380 
Fishery Bulletin 108(4) 
In the context of the ecosystem-based fisheries man- 
agement framework, every attempt should be made to 
reduce, where practical, the amount of bycatch. In view 
of the high mortality of the bycatch species taken by 
trawlers and gillnetters, commercial fishermen should 
be encouraged to explore ways of reducing the amount 
of bycatch and of increasing survival among discarded 
individuals. Thus, with trawling for example, fisher- 
men could explore the effectiveness of bycatch reduc- 
tion devices, reduce the duration of trawls and onboard 
handling time, and unload the catch into water tanks 
before sorting. In the case of gillnetting, fishermen 
could explore whether a reduction in the soak time of 
their nets leads to a decrease in the mortality of the 
bycatch and an increase in the market quality and 
thus the value of the flesh of the retained species. 
The biological and catch data produced during this 
and other studies on locally abundant bycatch species 
of elasmobranchs (White et al., 2001; 2002; White 
and Potter, 2005; Marshall et al., 2007) indicate that 
trawl, gillnet, and longline fisheries may be having 
a direct impact on the populations of these species 
in southwestern Australia. The acquisition of these 
data now enables managers to determine whether the 
impacts of commercial fisheries on the populations of 
bycatch species justify modifying fishing regulations 
to ensure that the risks to the sustainability of these 
species are reduced and that the integrity of the eco- 
system is thus maintained. Such risks could readily 
be achieved through the use of rapid assessment tech- 
niques, such as those described by Stobutzki (2001; 
2002) and Walker et al. (2005). 
Acknowledgments 
Special thanks are extended to the commercial fisher- 
men, and particularly to H. Gilbert, P. Dyer and A. 
Butler, whose help was invaluable for obtaining samples, 
to P. Coulson, D. French, and B. Farmer, who assisted 
in sampling, and to A. Hesp for his statistical advice. 
We also thank three anonymous referees for their con- 
structive comments, which have led to an improved 
manuscript. Funding for this project was provided by 
FISHCARE WA and Murdoch University. 
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