Mesoscale distribution and assemblage structure of fish larvae in the Kuroshio waters off eastern Taiwan

Abstract

The mesoscale distribution of fish larvae and its relationships with oceanographic features were examined among six cruises from four seasons in the Kuroshio waters off eastern Taiwan between May 2003 and November 2004. A total of 389 taxa (including two morpho-types) of fish larvae belonging to 106 families and 204 genera were identified from the samples. Families with higher numbers of species were Myctophidae, Scombridae, Stomiidae, Paralepididae, and Gobiidae. Maurolicus japonicus (relative abundance, 7.8%), Vinciguerria nimbaria (7.4%), Sigmops gracilis (6.5%), Cyclothone alba (5.5%), and Diaphus stubby type (5.0%) were the five most abundant taxa. Fish larvae abundance was lower in February and August 2004 than in other cruises, but without spatial variation in distribution. Although the predominant species were similar among cruises, species number and diversity were higher in May 2003 and lower in August 2004. Two larval fish assemblages were distinguished, one containing mainly autumn, winter, and spring and the other mainly spring and summer collections. The taxonomically diverse larval fish assemblage demonstrated that the Kuroshio waters off eastern Taiwan are a major transition zone between tropical and subtropical faunas. These communities are enriched by northward advection of larvae and early juveniles of many tropical species into subtropical waters via the Kuroshio Current. In addition, offshore transport of neritic fish larvae also increased the diversity of the larval fish assemblage in Kuroshio waters. The distribution of fish larvae was related to oceanographic features, with surface salinity, chlorophyll, and food sources being correlated to the abundance of fish larvae.