Bull. Jpn. Soc. Fish. Oceanogr. 73(3), Page 172-180, 2009   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 Nobuo Takagi1†, Kenji Morinaga2 and Hideaki Nakata3 1 Nagasaki Prefectural Institute of Fisheries, 1551-4 Taira, Nagasaki, Nagasaki 851-2213, Japan 2 National Fisheries Research Institute, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan 3 Faculty of Fisheries, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan †e-mail: takagi011141@pref.nagasaki.lg.jp 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. Key words: 24-h ADCP observation, daily mean current, warm water mass, Koshikijima Strait, continental margin