Distribution of late-stage phyllosoma larvae of Panulirus japonicus in the Kuroshio Subgyre

Abstract

The present study was undertaken in waters south of the Kuroshio Subgyre to examine and/or test Sekiguchi’s (1985, 1997) hypothesis about the larval recruitment processes of Panulirus japonicus by which the benthic populations of the species are maintained in Japanese waters. A total of 61 Panulirus phyllosoma larvae were collected in early summer; 56 belonged to P. japonicus, of which 30 were in the final stage, 24 in the subfinal stage, and 2 were too heavily damaged to permit identification of the stage. Most of the final-stage phyllosoma larvae were found in the northern part of the waters east of the Ryukyu Archipelago, whereas the larvae in the subfinal stage were found in the southern part. The present study supports Sekiguchi’s hypothesis that late-stage P. japonicus phyllosoma larvae are transported by the Kuroshio Countercurrent into waters east of the archipelago and then again enter the Kuroshio Current.

Distribution and dispersal of the early larval stages of the Japanese spiny lobsterPanulirus japonicusin the East China Sea

“…In the Kuroshio Current, southwest of Kyusyu Island, concentrations of the final stage (X) larvae were observed and sub-samples were identified as P. japonicus exactly after metamorphosis to the puerulus stage in the laboratory (Yoshimura et al 1999). Chow et al (2006b) supported the hypothesis that the main distribution area of P. japonicus larvae is in the Pacific Ocean as proposed in previous studies (Sekiguchi 1985;Yoshimura et al 1999;Inoue & Sekiguchi 2001;Sekiguchi & Inoue 2002), based on molecular larval identification.…”

“…Sekiguchi & Inoue (2002) showed their hypothesised route of larval migration in which larvae are dispersed southwestward along the south off the Kuroshio Current from the eastern end of the Kuroshio Current to east off Nansei Islands as they grow. Although Inoue & Sekiguchi (2001) suggested that the distribution of late and final-stage larvae found in the northwestern Pacific Ocean south of the Kuroshio Current supports part of the above hypothesis, Chow et al (2006a) highlighted the ambiguity of the identification of P. japonicus based on morphological characteristics only. In the Kuroshio Current, southwest of Kyusyu Island, concentrations of the final stage (X) larvae were observed and sub-samples were identified as P. japonicus exactly after metamorphosis to the puerulus stage in the laboratory (Yoshimura et al 1999).…”

Spiny lobster development: where does successful metamorphosis to the puerulus occur?: a review

“…The larval cycle of P. japonicus appears to be intimately related to the activities of the Kuroshio Current (Inoue and Sekiguchi 2001) and the distribution of final phyllosomas, as well as puerulus settlement, is probably influenced by the abovementioned changes in its pathway. Yoshimura (2005) had data (4 specimens) of finalstage phyllosomas of P. japonicus metamorphosing to pueruli in relation to the Kuroshio Current off southern Japan.…”

“…Inoue and Sekiguchi (2001) sampled beyond the shelf, but adjacent to it, in waters south of the Kuroshio Subgyre which is south of Kyushu, Japan. They clearly showed that the phyllosomas of P. japonicus were beyond the shelf and most of the 30 finalstage larvae caught were in the northern part of the waters east of the Ryuku Archipelago (Inoue and Sekiguchi 2001, Fig.…”

“…A number of studies of the distribution of phyllosomas of P. japonicus have been conducted, including those of Yoshimura et al (1999), Inoue and Sekiguchi (2001) and Yoshimura et al (2002). Inoue and Sekiguchi (2001) sampled beyond the shelf, but adjacent to it, in waters south of the Kuroshio Subgyre which is south of Kyushu, Japan.…”