Fowler et al.: Distribution and abundance of tuna larvae in near-reef waters of the Coral Sea 
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0 4 8 12 16 20 
Distance from outer reefs (km) 
Figure 5 
Mean abundance (larvae/100 m 2 + l T± standard 
error]) of larvae with distance from the outer reefs 
of the Great Barrier Reef for Euthynnus affinis 
(kawakawa, full line) larvae during the early 
November and early February cruises, and for 
Auxis-Euthynnus (dashed line) larvae during the 
early February cruise, in the Coral Sea. Data points 
indicate the midpoint of sampling blocks (A-E) by 
distance, except for the Great Barrier Reef Lagoon 
the display of which (L on the x axis) is categorical 
and does not reflect the true distance from the other 
blocks. The y axis is log 10 scale. The x axis shows 
the width of each sampling block (km). The hatched 
area on the x axis indicates the position of the outer 
reef area of the Great Barrier Reef. No significant 
differences were found among blocks on either the 
early November (ANOVA, P=0.14) or early February 
(ANOVA, P=0.11) cruises for E. affinis larvae, or 
on the early February cruise (ANOVA, P=0.06) for 
Auxis-Euthynnus larvae. Auxis-Euthynnus larvae 
were not sufficiently abundant on the first cruise 
for statistical analysis. Abundance data were not 
obtained for block D. 
than those determined for oceanic sites elsewhere (24-80 
larvae/100 m 2 , Strasburg, 1960; Nakamura and Matsu- 
moto, 1966), the larvae of most tuna species were more 
abundant within 5.6 km of the Great Barrier Reef than 
further offshore in the Coral Sea. This pattern was 
consistent among cruises for particular taxa, indicating 
that near-reef larval distributions persist over seasonal 
time scales. 
Larvae of the genus Thunnus may generally be more 
abundant in near-reef waters than farther offshore, 
because in all studies of tuna larvae in near-reef wa- 
ters consistently high concentrations or abundances of 
Figure 6 
Mean abundance (larvae/100 m 2 +l [± standard error]) 
of Katsuwonus pelamis (skipjack tuna) larvae with 
distance from the outer reefs of the Great Barrier 
Reef during four cruises in the Coral Sea. Data points 
indicate the midpoint of sampling blocks (A-E) by 
distance, except for the Great Barrier Reef Lagoon 
the display of which (L on the x axis) is categorical 
and does not reflect the true distance from the other 
blocks. The y axis is log 10 scale. The x axis shows the 
width of each sampling block (km). The hatched area 
on the x axis indicates the position of the outer reef 
area of the Great Barrier Reef. Within a cruise, if 
data points share a lowercase letter, they were not 
significantly different from each other according 
to Tukey’s post hoc test. Abundance data were not 
obtained for block D. 
Thunnus larvae have been found there. Greatest abun- 
dances of Thunnus larvae were often found within 2 km 
of the outer Great Barrier Reef in the present study, 
