Larval transport of the amphidromous goby Sicyopterus japonicus by the Kuroshio Current

Abstract

Oceanic larval transport of an amphidromous goby, Sicyopterus japonicus, was simulated using a Lagrangian modeling approach to validate the hypothesis that the Kuroshio Current could transport their larvae from Taiwan to northern Japan, which is the geographic range of this species. Simulated particles released at a 50 m depth from the off southernmost part of Taiwan reached Japan from southern Kyushu to northern Japan after 180 days. In contrast, many particles released at 120 m were trapped in eddies in the northwestern part of the subtropical gyre for 90 to 120 days and never reached the southern Japanese coast. These simulations showed that transport at a 50 m depth would enable many larvae to distribute over their entire species range after being transported away from Taiwan. The otolith growth increments of 30 larvae from Wakayama in April to August 2007 showed their oceanic larval duration ranged from 185 to 270 days, suggesting they have sufficient time as larvae for their transport from Taiwan to northern Japan. These results supported the hypothesis of larval transport described above and suggested a possibility that the Kuroshio would play an important role to maintain the apparent lack of population structure of S. japonicus from Taiwan to northern Japan