180 
Abstract— The diet of Plectropomus 
leopardus (Serranidae, Lacepede 1802) 
was examined on two pairs of reefs in 
the Cairns Section of the Great Barrier 
Reef Marine Park, Australia. For both 
pairs, one reef was open to fishing and 
the other had been closed to fishing for 
eight years; however zoning appeared 
to be ineffective as there was no differ- 
ence in the size structure of leopard cor- 
algrouper populations on either open 
or closed reefs. Two fishing methods 
were used to sample reefs concurrently, 
and the size structure and diet of 
P. leopardus that were speared ran- 
domly (n= 587) were compared to sam- 
ples caught by line (n= 85). Adult P. 
leopardus were highly piscivorous (96% 
of prey was fish by number), and two 
families of fishes, Pomacentridae and 
Labridae, composed approximately half 
of their diet (index of relative impor- 
tance=48.4%). Numerical composition 
of fish in the diet varied significantly 
among reefs, but there were no patterns 
related to reef closures when fish prey 
were classified by taxa or by their habi- 
tat. Fishes categorized as living in the 
demersal reef habitat were the domi- 
nant prey consumed, followed by mid- 
water fishes. When the data from reefs 
were pooled, the abundance of families 
in the diet differed between locations 
(north and south) but not between fish- 
ing zones. Dietary overlap was high 
between the different fishing zones and 
was very high in relation to naturally 
occurring spatial and temporal vari- 
ability in the diet of P. leopardus found 
in other studies. With line fishing larger 
and hungry fish are caught, and the 
few data on natural prey suggest ten- 
tatively that line catches are biased 
toward P. leopardus feeding on pelagic 
fishes. The coral reefs and surrounding 
waters provide the major food source of 
P. leopardus , whereas sandy areas are 
much less important. Our data suggest 
that the coral trout fishery is resilient 
to changes in abundances of particular 
prey species because the diet of P. leop- 
ardus is broad and because the two 
major prey families are diverse and 
abundant on coral reefs. 
Manuscript accepted 25 April 2000. 
Fish. Bull. 99:180-192 (2001). 
The diet of the large coral reef serranid 
Plectropomus leopardus in two fishing zones 
on the Great Barrier Reef, Australia 
Jill St John 
Garry R. Russ 
Department of Marine Biology 
James Cook University 
Townsville, Queensland 4811 Australia 
Present address (for J. St John): Western Australian Marine Research Laboratories 
PO Box 20 
North Beach, Western Australia 6020, Australia 
E-mail address (for J. SUohn): jstjohn@fish.wa.gov.au 
Ian W. Brown 
Southern Fisheries Centre 
PO. Box 
Deception Bay, Queensland 4508 Australia 
Lyle C. Squire 
27 Barrett St. 
Bungalow, Queensland 4870 Australia 
Groupers (Serranidae) are an impor- 
tant fishery resource throughout the 
tropics (Ralston, 1987; Heemstra and 
Randall, 1993; Polunin and Roberts, 
1996) and are a favored target species 
of fishermen (Bohnsack, 1982; Randall, 
1987; Koslow et ah, 1988; Russ and 
Alcala, 1996). Like many other large 
piscine predators, the life history char- 
acteristics of groupers ( Bohnsack, 1982; 
Russ, 1991) make them vulnerable to 
overfishing (Sluka and Sullivan, 1998). 
Unlike most other multispecies trop- 
ical habitats, the Great Barrier Reef 
(GBR) supports a line fishery that tar- 
gets relatively few genera (Russ, 1991). 
The groupers of the genus Plectropo- 
mus support the most valuable commer- 
cial fin-fishery in Queensland (Trainor, 
1991), with an annual value of $A10 
million. Groupers bring a consistently 
high price (about $20/kilogram retail 
for fillet) on the Australian market 
and are highly valued in the “live ex- 
port” market to Asia (Miles 1 ) Also, grou- 
pers are targeted by recreational line 
(Blarney and Hundloe 2 ) and spear fish- 
ermen (Steven 3 ), and recreational fish- 
ing is expanding with the rapid growth 
of the tourist industry on the GBR. 
Plectropomus leopardus 4 is the domi- 
nant component of the three main coral 
trout species caught on the GBR by all 
fishermen (Williams and Russ, 1994; 
Steven 3 ), and by Australian standards, 
this species is subjected to considerable 
fishing pressure. 
Intense fishing pressure has been im- 
plicated in the drastic declines of grou- 
per populations off Florida and the Ca- 
ribbean (Sadovy, 1994; Bohnsack et al., 
1994). In Australia, fishery managers 
have already detected a decline in abun- 
1 Miles, A. 1997. Research, not rumors, 
needed for live fishing industry. Exploring 
Reef Science. May newsl. [Available from 
CRC Reef Research Centre, James Cook 
University, Townsville 4811, Australia.] 
2 Blarney, R. K., and T. J. Hundloe. 1991. 
Characteristics of recreational boat fishing 
in the Great Barrier Reef region. Unpubl. 
report to the Great Barrier Reef Marine 
Park Authority (GBRMPA) PO Box 1379, 
Townsville, Queensland 4810, Australia. 
3 Steven, A. 1988. An analysis of fishing 
activities on possible predators of the crown 
of thorns starfish (Acanthaster planci ) on 
the Great Barrier Reef. Unpubl. report 
to GBRMPA, PO Box 1379, Townsville, 
Queensland 4810, Australia. 131 p. 
4 The official common name of Plectropomus 
leopardus is leopard coralgrouper, formerly 
known as bluedotted coraltrout (Heemstra 
and Randall, 1993). 
