Zoological Studies

Vol. 37 No. 1, 1998

Seasonal and Hydrographic Variations of Ichthyoplankton Density and Composition in the Kuroshio Edge Exchange Area off Northeastern Taiwan

Jiunn-Bin Huang and Tai-Sheng Chiu*

Department of Zoology, National Taiwan University, Taipei, Taiwan 106

Jiunn-Bin Huang and Tai-Sheng Chiu (1998) A total of 327 ichthyoplankton samples were taken during 14 cruises from June 1989 to September 1992 in the waters off northeastern Taiwan. The density of ichthyoplankton was lowest in winter, increased in spring, reached the maximum in summer, and declined in autumn. Average densities in the 3 hydrographic ecotopes indicate that the ichthyoplankton density was highest in the East China Sea Shelf (ECS), moderate in the Kuroshio Current (KUR), and lowest in the mixing zone (MIX). In total, 59 789 individuals of ichthyoplankton assigned to at least 124 families and 547 species were collected. The major ichthyoplankton species, comprising about 60% of the total catch, were distinctive in different seasons and waters. Decapterus spp. (14.01%) and Auxis spp. (6.23%) were abundant in spring; Auxis spp. (6.91%) and Benthosema pterotum (5.80%) in summer; B. pterotum (55.23%), gobiids (4.14%), and Synagrops sp. (3.17%) in autumn; and B. pterotum (15.35%) and Gonostoma gracile (7.48%) in winter. The abundant ichthyoplankton species in the 3 hydrographic ecotopes were B. pterotum (22.98%) and Auxis spp. (5.11%) in ECS; Decapterus spp. (28.60%) and Auxis spp. (7.10%) in MIX; and B. pterotum (5.61%) and Vinciguerria nimbaria (4.43%) in KUR. The dendrogram based on major ichthyoplankton species exhibits 7 species-associated groups.

Key words: Larval fish, East China Sea Shelf, Kuroshio.

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