Distribution of fish larvae in the oceanic tropical and subtropical western Pacific in January, 2000

A total of 18,461 fish larvae excluding about 280 leptocephali were collected from 24 IKMT net stations at night during R/V Hakuho maru cruise KH-00-1 in the oceanic region from Tokyo, Japan to Brisbane, Australia, in January, 2000. They were identified to 76 families, 98 genera and 229 taxa inclusive of 140 species. Dominant families were in the order of Myctophidae, Engraulidae, Phosichthyidae, Gonostomatidae, and so on, and dominant species were in the order of an engraudid Encrasicholina punctifer, a phosichthyid Vinciguerria nimbaria, a gonostomatid Cyclothone alba, a myctophid Ceratoscopelus warmingii, and so on. Using the cluster analysis of similarity index of fish larvae, four major areas of stations were distinguished : area A, three stations north of 18°N; B, seven stations between 15°and 4°N; C, seven stations between 0°and 14°S; and D, five stations south of 19°S. The density and number of taxa of fish larvae were higher and the diversity index lower in the southern two areas than in the northern two ones. Dominant larvae were those of mesopelagic fishes with the ratio of more than 78% in the areas A and D, and were those of mesopelagic ones with the ratio of 53-59% and of epipelagic ones with the ratio of 22-32% in B and C