209 
Evaluations of the Nordmore grid and 
secondary bycatch-reducing devices 
(BRD's) in the Hunter River 
prawn-trawl fishery, Australia 
Matt K. Broadhurst 
Steven J. Kennedy 
NSW Fisheries Research Institute 
RO. Box 2 1 , Cronulla, New South Wales 2230, Australia 
E-mail address: broadhum@fisheries.nsw.gov.au 
John W. Watson 
Ian K. Workman 
Mississippi Laboratories, National Marine Fisheries Service 
Pascagoula Facility, RO. Drawer 1207, Pascagoula, Mississippi 39568-1207 
Abstract .—Several bycatch-reduc- 
ing devices IBRD’s) were compared for 
their effectiveness in reducing bycatch 
while maintaining catches of prawns in 
an estuarine prawn-trawl fishery in 
New South Wales (NSW), Australia. A 
solid separator-panel (the Nordmpre 
grid), a soft separator panel (the com- 
mercially used blubber chute), and four 
secondary BRD’s (the fisheye, extended 
mesh funnel, Allerio Brothers grid, and 
square-mesh panel) each attached to a 
Nordmpre grid, were compared against 
each other in a series of paired compari- 
sons in the Hunter River prawn-trawl 
fishery. The results showed that the 
Nordmpre grid and all secondary BRD’s 
caught less bycatch and more prawns 
than the commercially used blubber 
chute. Most bycatch seemed to escape 
with use of the Nordmpre grid, and 
there was no significant advantage in 
adding a secondary BRD to this design. 
The efficiency of the Nordmpre grid has 
led to its voluntary adoption by many 
commercial prawn-trawl fishermen 
throughout NSW estuaries. 
Manuscript accepted 15 November 1996. 
Fishery Bulletin 95:209-218 (1997). 
In New South Wales (NSW), Aus- 
tralia, estuarine prawn-trawling 
occurs in five localities and is val- 
ued at approximately A$7 million 
per annum. Like the majority of the 
world’s prawn-trawl fisheries, sig- 
nificant numbers of nontarget or- 
ganisms, or bycatch, are captured 
incidentally with targeted prawns 
(for reviews see Saila, 1983; Andrew 
and Pepperell, 1992; Alverson et al., 
1994; Kennelly, 1995). 
In recent years, bycatch from 
these fisheries has become of in- 
creasing concern to a broad cross 
section of the fisheries community. 
As a result, a 3-yr observer-based 
study was undertaken from 1990 to 
1992 to quantify the distributions 
and abundances of bycatch species 
(Liggins and Kennelly, 1996; Ken- 
nelly 1 ). The results from these stud- 
ies showed that, despite large spa- 
tial and temporal variabilities in the 
bycatches of many species, some 
juveniles of commercially and 
recreationally important species 
were caught in large numbers 
throughout the trawling seasons. 
The quantities involved raised con- 
cerns over the potential impacts of 
prawn-trawling on subsequent 
stocks of these species. These con- 
cerns led to the current investiga- 
tion, which examines various modi- 
fications to trawling gear and trawl- 
ing practices that minimize unde- 
sirable bycatches while maintaining 
catches of prawns. 
A number of recent attempts to 
exclude bycatch from prawn-trawls 
have concentrated on modifications 
that incorporate bycatch-reducing 
devices (BRD’s) (Christian and 
Harrington, 1987; Averill, 1989; 
Kendall, 1990; Isaksen et al., 1992; 
Rulifson et al., 1992; Broadhurst et 
al., 1996). In previous experiments 
(Broadhurst and Kennelly, 1994, 
1995, 1996; Broadhurst et al., 1996) 
we showed that the successful ap- 
plication of various BRD’s is specific 
to individual fisheries and depends 
upon several factors, including the 
type of species to be excluded. Fur- 
ther, to promote acceptance by in- 
dustry, BRD’s should be designed so 
that they do not adversely influence 
normal commercial operations. 
1 Kennelly, S. J. 1993. Study of the by- 
catch of the NSW east coast trawl fishery. 
Final rep. to the Fisheries Research and 
Development Cooperation. Project 88/ 
108, ISBN 0 7310 2096 0, 520 p. 
