|Immigration, settlement and mortality of flounder (Paralichthys olivaceus) larvae and juveniles in a nursery ground, Shijiki Bay, Japan|
Tanaka, M.; Goto, T.; Tomiyama, M.; Sudo, H. (1989). Immigration, settlement and mortality of flounder (Paralichthys olivaceus) larvae and juveniles in a nursery ground, Shijiki Bay, Japan. Neth. J. Sea Res. 24(1): 57-67
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
|Authors|| || Top |
- Tanaka, M.
- Goto, T.
- Tomiyama, M.
- Sudo, H.
The occurrence, distribution and abundance of larvae and juveniles of a Japanese flounder, Paralichthys olivaceus were investigated in Shijiki Bay, south-western Japan, from 1982 through 1987, with special reference to immigration, settlement and mortality in this nursery ground. Sampling for pelagic larvae and settling and settled juveniles revealed that immigration and settlement occur during the late phase of metamorphosis, when flounders immigrate from coastal waters and settle in the near-shore sandy nursery area. Immigration of metamorphosing larvae begins in early April and continues until early June. The recruitment of flounders into the nursery ground was found to occur in several dinstinct phases, coinciding with spring tides. The semi-lunar periodicity found in the immigration of flounders may be due to the combination of landward tidal currents during spring tides and the tide-related vertical movements of metamorphosing flounders. Population size appeared to decrease rapidly during the first week after settlement, when lengths ranged from 11 to 14 mm. Field evidence demonstrated that heavy mortality may occur during the early phases of settlement, the extent depending on annual flounder densities and food abundance. Cannibalism of early-settled larger flounders on late-settled smaller flounders seemed to occur frequently in the nursery ground, and was more likely to occur under conditions of food deficiency and higher population densities. Thus, predation related to starvation could be one of the most important future research targets in determining recruitment dynamics in nursery areas.