Abstract
One of the most distinctive and unique characteristics of the early life history of flatfishes is the “metamorphosis” and “settlement” from pelagic, symmetrical larvae to benthic, asymmetrical juveniles, while undergoing profound internal and external changes represented by eye migration, and a habitat shift from spawning to nursery areas. The nursery habitats of flatfishes range from shallow freshwater areas to deepwater areas, and the ontogenetic migrations to specific nurseries vary widely among species. Settlement to the optimal nurseries is critical for flatfishes because the recruitment variability appears to be determined during the pelagic dispersal phase through density-independent mortality processes. First, information on the metamorphosis, settlement and ontogenetic migration processes of flatfishes, mainly Pleuronectidae and Paralichthydae, is reviewed from the points of biological characteristics of each species (e.g. spawning strategy, metamorphic size, vertical movement, lateralized swimming behavior and settlement) and physical features of each locality (e.g. currents, tide, temperature and salinity). Second, the variability on the ontogenetic migrations and recruitment processes of five pleuronectid species, which settle on the different nurseries from rivers to offshore areas, is discussed from the point of the ontogenetic developments of morphology and low-salinity adaptability. This paper reveals the variability and flexibility of recruitment strategies of flatfishes.
