184 
Fishery Bulletin 99(1 ) 
Stomach contents of fish caught by the two 
methods 
Although the proportion of P. leopardus with empty stom- 
achs did not differ between the line-caught and speared 
catch (Fisher’s exact test (1 |=0.12, P=0.81), the proportion of 
the catch with natural prey in their stomachs was sig- 
nificantly higher in speared fish (Fisher’s exact test [x p7.8, 
P=0.01) (Table 2). As expected, a much higher proportion 
of line-caught fish had consumed the bait S. neopilchardus 
(Table 2); however, five P. leopardus that were speared at sites 
where line fishing had not occurred, also had consumed bait. 
cl 
o 
© 
<D 
E 
Open to fishing 
North 
South 
Nathan Reef 
Potter Reef 
Spear 
Line 
North 
Closed to fishing 
South 
Fork length (cm) 
Figure 2 
The length-frequency distributions of P. leopardus collected by line and spear 
from the four reefs, Nathan (n=191) , Wardle (n=153), Potter (n=178), and 
Noreaster (n = 150) Reefs. 
Assessment of natural diet 
Type of prey Plectropomus leopardus 
on the four reefs fed mostly upon fish, 
some crustaceans, and a few cephalo- 
pods (Table 3). Six pieces of hard coral 
that were found in the stomachs of P. 
leopardus at three reefs were considered 
to have been ingested incidentally with 
prey and were excluded from the analy- 
sis. The proportions of fish, crustaceans, 
and cephalopods in the diet of P. leop- 
ardus did not vary significantly among 
the four reefs (Fisher’s exact test [6] =4.84, 
P=0.56, Table 3). Plectropomus leopardus 
were highly piscivorous. Fish accounted 
for 95.7% of their diet. 
General fish diet Of the 468 prey fish in 
the diet of P. leopardus, 40% were iden- 
tified to 22 families (Table 4). The abun- 
dance of fish prey in a family ranged from 
one (nine families, Table 4) to 47 individ- 
uals (Pomacentridae, Table 4), and total 
digested prey weights ranged from 0.12 g 
to 730 g per family (Table 5). The average 
weight of an individual prey item was 
13.7 g. 
Two families, Pomacentridae and Lab- 
ridae, dominated the diet by number (Ta- 
ble 4) and by weight (Table 5) and were 
the most important prey of P. leopardus 
(IRI=27 .8% and 7f?/=20.6% respectively, 
Table 6). Three families, Scaridae, Clu- 
peidae, and Caesionidae, were the next 
most important prey, each representing 
about 10% of the diet by IRI and at least 
Table 1 
Summary of 672 P leopardus collected from the Cairns section of the Great Barrier Reef Marine Park by line and spear fishing, 
including location of the reef pairs, names of reefs, their fishing status, and date of sampling. 
Sample size in) 
Location of reef pair 
Reef pair 
Fishing zone 
Date in 1992 
Line 
Spear 
Total 
North 
Nathan 
open 
20-22 Jan 
33 
158 
191 
Wardle 
closed 
23-25 Jan 
10 
143 
153 
South 
Potter 
open 
24-26 Feb 
23 
155 
178 
Noreaster 
closed 
27-29 Feb 
19 
131 
150 
