Palinurid phyllosoma larvae and their distribution in winter off the Pacific coast of Japan

Abstract

SUMMARY: Widespread ichthyoplanidon samplings were conducted along the Pacific coast of Japan in winter 1989 to 1992 to monitor abundance of larval Pacific saury. Middle and late stage phyllosoma larvae of the Palinurldae were found among the surface net samples. All of these larvae were caught at night, and they were distributed widely south of the Kuroshio. They were identified as Form A, and were likely to be the larvae of the Japanese spiny lobster, Panulinis japonicus, or of the 'P. longpes complex' on the basis of their morphological characteristics and the known adult distribution area. KEY I4 RDS: phyllosoma, spiny lobster, Panulirus, larval distribution, KuroshioThe larval life of the paTmurid spiny lobster is extremely long, ranging from a few months to almost 2 years before the last phyllosoma stage metamorphoses to the post-larval stage." In the Japanese spiny lobster, Panulirus japonicas (Decapoda, Palinuridae), rearing experiments in the laboratory have shown that metamorphosis to the post larval stage occurs between 231 and 417 days after hatching.2,3,4} However, this long larval life has not yet been proved in the ocean, because the number of captured wild phyllosoma larvae around Japan is not large and serial growth data on wild larvae have not yet been published Among 5 forms (A-E) of palinurid larvae captured around Japan,) Form A is thought to be P. japonicus.6) Although 127 Form A larvae with body lengths exceeding 20 mm have been captured hitherto,) far fewer young stages smaller than 20 mm long have been caught, with the exception of new hatchlings s) Moreover, late-stage phyllosoma of the P. japonicas group may be morphologically similar 6,9) and Matsu da. and Yamakawar10) found no morphological differences between P. japonicas and P. longipes larvae reared in the laboratory.In recent years, relatively large number of Form A larvae have been collected in and around the Kuroshio off southern Kyusyu, thus proving the usefulness of oblique and surface towing at night with relative large samplers like the Isaacs-Kickd midwater trawl!) According to Yoshimuua et al.7, final-stage larvae concentrated in and around the Krnoshio and younger larvae are probably distributed in the southern area of this current. The wild late and final-stage Form A larvae were identified as P. japonicas, because those were captured in mid-summer, which is just before or in the middle of the main post larval settlement season of P. japonicas but should not of P. longipes, adding the species confirmation. made by examinaton of metamorphosed post-larvae. However, species identification of late-stage Form A larvae that are not captured in summer and of younger stages is stilll difficult.We examined plankton samples caught by surface towing of larva nets during 4 winter seasons in a wide area off the Pacific coast of Japan. We found 11 palinuuid phyllosoma larvae, of which the morphological characteristics matched those of Form A) Here we describe the morphology and distribution of middle and late-stage Form A phyllosoma ...

Behavior constrains the dispersal of long-lived spiny lobster larvae

“…Our conclusions regarding diel vertical migration in P. argus larvae also agree with observations of larval vertical distribution noted in field studies conducted during the day and night (Buesa 1970, Baisre 1976, Yeung & McGowan 1991. Diurnal vertical migration by late-stage spiny lobster larvae has also been documented in P. japonicus (Yoshimura et al 2002) and P. cygnus (Phillips & Pearce 1997), but appears to be absent in Jasus edwardsii (Bradford et al 2005). Light may not be the only cue used by decapod larvae for vertical migration.…”

“…Our goal was to construct behavioral rules that resulted in modeled larval depth distributions that reflected the kind of OVM indicated in field plankton studies (Yeung & McGowan 1991, Yoshimura et al 2002, including our own. The resultant age-specific larval depth distributions predicted by the model were then converted to size-specific depth distributions for comparison with observed field data to obtain a good match (see Results).…”

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

“…The numbers of phyllosomas (especially the final stage) caught during these and earlier cruises were low and as reported by Yoshimura et al (2002) ''Very little is known about the scale and processes of transport of P. japonicus larvae. The problem lies in the ambiguity of species identification of larvae and the small number of samples collected from the plankton.''…”

“…Yoshimura (2005) had data (4 specimens) of finalstage phyllosomas of P. japonicus metamorphosing to pueruli in relation to the Kuroshio Current off southern Japan. Because mid-and late-stage phyllosomas were found in the ocean south of the Kuroshio, whereas most final-stage larvae were caught within this current (Yoshimura et al 1999(Yoshimura et al , 2002, Yoshimura (2005) inferred that metamorphosis occurs offshore within the Kuroshio Current as discussed above. Yoshimura (2005) also added that their 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.…”