Structure and variation of the north to northeastward current observed on the continental margin of the Amakusa-nada and southern part of Goto-nada through winter to spring

Abstract

North to northeastward daily mean currents were detected on the continental margin of the Amakusa-nada and southern part of Goto-nada by 24-h ADCP observations conducted through winter to spring in 2004－2007. These currents corresponded to northward movement of warm water masses extending from the Koshikijima Strait or western offshore of the Koshiki Islands. The current speeds of the warm water masses were appreciably large (40 cm· s^－1 at maximum), and often exceeded the speed of tidal current around these regions. It is suggested that the north-northeastward currents could play an important role in the egg and larval transport of anchovy to Tachibana Bay, where anchovy is a major target of fisheries.