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Fishery Bulletin 106(4) 
Figure 7 
Size-frequency distributions for Katsuwonus pelamis (skipjack tuna) larvae from inshore and 
offshore zones during the (A) early February, (B) late February, and (C) late November cruises 
in the Coral Sea. Standard length (mm) of larvae was measured to the nearest 0.1 mm. P-values 
refer to the significance of Kolmogorov-Smirnov (K-S) tests conducted between the inshore 
and offshore zones within a cruise. 
and, as with our findings, small (<3.0 mm SL) Thun- 
nus spp. larvae were -10 times more abundant 1.8 km 
offshore, than 9.3 km offshore, of the leeward side of 
Oahu Island (Boehlert and Mundy, 1994). In an earlier 
study at Oahu Island high concentrations (up to 220 
larvae/500 m 3 ) of T. albacares larvae were found within 
2 km of shore (Miller, 1979), and similar concentrations 
(up to 224 larvae/500 m 3 ) of Thunnus spp. larvae (ei- 
ther T. albacares or T. alalunga ) were found in samples 
taken within 200 m of reefs in French Polynesia (Leis 
et al., 1991). The present study is the first to investigate 
near-reef distributions of tuna larvae outside of central 
Pacific Ocean island environments and thus extends the 
near-reef distributional pattern to include continental 
slope environments of the western Pacific Ocean, but 
further research on on-offshore patterns of abundance 
in other regions is required to confirm the generality 
of this phenomenon. 
Considerable differences in on-offshore larval distri- 
butions may exist among genera of tuna, perhaps even 
among species, and these differences may not neces- 
sarily reflect similarities in adult distributions. We 
have confirmed the opposing on-offshore distributions of 
Thunnus spp. and K. pelamis larvae previously discov- 
ered in Hawaii, where Thunnus spp. larvae were more 
abundant near the reef on the leeward side of Oahu 
Island, while K. pelamis larvae increased in abundance 
in the offshore direction (Boehlert and Mundy, 1994). 
Interestingly, the on-offshore distributions of Thunnus 
spp. larvae in the Coral Sea were more similar to the 
larval distributions of E. affinis (and possibly Auxis 
spp.) than to the distributions of K. pelamis larvae. 
