Larval recruitment and fisheries of the spiny lobster Panulirus japonicus coupling with the Kuroshio subgyre circulation in the western North Pacific: A review

Panulirus japonicus is an important target for fisheries in Japan. Characteristics of long distance larval transport and recruitment of P. japonicus have been revealed based on drifter studies and larval sampling. Larval recruitment of the lobster is completed within the Kuroshio Subgyre circulation, i.e., early stage phyllosomas that are released in Japanese coastal waters in summer (July-September) are transported into the Kuroshio region; larvae are then transported to the Kuroshio Counter-Current region south of the Kuroshio; these larvae are then transported into the waters east of the Ryukyu Archipelago where subfinal/final-stage phyllosomas and pueruli enter the Kuroshio again and are transported to different locations of Japanese coastal waters through the Kuroshio in the summer of the following year. Using mtDNA sequences for the COI region of P. japonicus juveniles and adults, no significant population subdivision was detected among distant locations. There was no characteristic geographical distribution pattern for haplotypes, supporting the hypothesis that these benthic individuals are sustained by a common pool of phyllosomas through long distance larval transport by phyllosomas within the Kuroshio Subgyre circulation. This scenario is also supported by the examination of longterm variation in P. japonicus catches as follows. Two clusters (A, B) of regions located east (A) and west (B) of the cape Shionomisaki at the southern tip of the Kii Peninsula were identified. There was a significant positive relationship between the Kuroshio index and the catch index two years later for cluster A. This relationship suggests that annual variation in P. japonicus catch may be determined by the variation in puerulus recruitment through the Kuroshio. Relationships between these two clusters varied depending on three periods, which corresponded to the three climate regimes (i.e., years before 1976, from 1977 to 1988, and after 1989). Significant negative relationships were detected between the catch index of these two clusters from 1975 to 2001.