Ichthyoplanktonic fauna in the Kii Channel is usually dominated by eggs of the sea bass Lateolabrax japonicus and larvae of the greenling Hexagrammos otakii in winter. They are mainly spawned in the inner parts of the channel, or those further inside. The sea bass eggs and the greenling larvae are strictly neustonic. Their geographical distribution in the Kii Channel are essentially influenced by the rise and fall the two water masses, the coastal and oceanic waters. Both the sea bass eggs and the greenling larvae are always distributed most densely just inside the boundary zone. When the oceanic water is prevailing their distribution become restricted to the inner part of the Kii Channel, while when the oceanic water is retreating offshore, their distribution expands outside the channel.