296 
Fishery Bulletin 107(3) 
in discard mortality of school prawns of more than a 
third. When combined with other selective mechanisms, 
such as square-mesh codends that reduce the catches of 
school prawns of nontarget sizes, the water tray should 
contribute towards the sustainability of trawling in 
New South Wales rivers. 
Acknowledgments 
This work was funded by the New South Wales Depart- 
ment of Primary Industries and the Australian Fish- 
eries Research and Development Corporation (Grant 
no. 2005/056) and performed according to New South 
Wales Department of Primary Industries animal care 
and ethics protocols. Thanks are extended to the 
Clarence and Hunter river commercial fishing crews 
for their ongoing support, and to P. Butcher, K. Hall, 
S. McGrath and especially B. Paterson for advice and 
assistance. 
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