2023 Volume 87 Issue 1 Pages 1-14
Japanese temperate bass Lateolabrax japonicus spawns offshore in midwinter and its larvae and juveniles occur in nearshore shallow waters in early spring. To better understand the transport mechanism of planktonic eggs and larvae of L. japonicus, quantitative sampling was conducted using a large-sized plankton net in Tango Bay and adjacent waters (western Wakasa Bay, Sea of Japan) from December 2019 to March 2020. The sampling of horizontal distributions identified the main spawning ground as ranging from the middle of the bay to the east side of the adjacent waters, where eggs occurred abundantly. The sampling of vertical distributions found eggs mainly at the surface, while yolk-sac and pre-flexion/flexion larvae were found at >40 and 10–20 m deep, respectively. As northwesterly winds of the winter monsoon are known to drive water circulation in Tango Bay, pre-flexion/flexion larvae are likely transported toward the innermost part of the bay through the middle layers by the circulation. We conclude that the main spawning ground is formed upstream of the circulation and therefore contributes to the transport of eggs and larvae to nursery grounds, which are distributed mainly in the innermost part of the bay.
