The main purpose of this study was to understand and estimate the gathering areas of pelagic fish schools in northeastern waters of Taiwan. The purse seine fishery operates near the area of the Kuroshio Current front during the spring. In this study, we found that the Kuroshio Current front obviously moved southward in 2003, and most of the purse seiners were found operating along the outer edge of the current, while the Danish seiners were operating in the southward area of the Kuroshio Current front. The body length frequency distribution of the catch was larger than those of the last few years. Based on the CTD collected data in this study, we found that a cold eddy was located at 25°18'N, 122°18'E in July 2002, and its concentration of chlorophyll a was high at up to 14.0 μg/L. Based on values of fish intensity using an echo sounder, we also proved that a high density of pelagic fish schools gathered around the edge of the Current front. In July 2003, the cold eddy was located near 25°40'N, 122°40'E, and the concentration of chlorophyll a in the center of the cold eddy was higher than that of the outer layer. During 8 ~ 11 February 1999, the CTD data collected at 25°20'N, 120°3'E showed that Mainland China coastal cold water with a seawater temperature of less than 17°C and salinity of less than 33.0 ppt covered the Current which had a seawater temperature of greater than 20°C and a salinity of greater than 34.0 ppt. We found that the fish schools seemed to inhabit an area of the Taiwan warm water current. In the winter, a strong current of Mainland China coastal cold water running southward along with the northeast monsoon was found at locations west of 122°E.