The mechanism of formation of mackerel fishing grounds in the waters off northeastern Taiwan was studied based on data obtained from the NOAA-HRPT satellite remote sensing system of TFRI, fishing vessels, and meteorological observatories. These data include sea surface water temperature images, fishing and oceanographic conditions and weather reports from 1990 to 1991. The preliminary results were as follows:
Mackerels were observed mainly during autumn and winter in the waters off northeastern Taiwan. This fishing ground was found in the oceanic front where the main Kuroshio current and the China coastal current converges. Using the aid of satellite macroscopic scanning, fishermen can easily locate the fishing grounds with upwelling and oceanic front.
Another mackerel fishing ground formed by upwelling was also found in the waters around Peng-chia-yu. This fishing ground is mainly around the peripheral part of the upwelling area, which was a counterclock gyre. The area is characterized by low temperature and high salinity, and an aggregation of dark green phytoplankton. During summer, oceanic fronts are rarely observed. Thus, fishing vessels usually seek for upwellings for possible good fishing conditions. When low pressure or typhoon occurs, upwelling is formed.