FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

In order to investigate the movements of tagged black porgy ( Acanthopagrus schlegeli ) after releasing, data of tagging in the northern Taiwan from 1989 to 1993 were analysed. The recapture rate, percentage of recapture in the catch, direction and distance of movement, number of days on recapture, and the accumulative recapture rate were included. Black porgy longer than 75mm were tagged with anchor tags, and smaller ones were marked with ventral fin clip. Recapture rates varied greatly between different areas. The highest recapture rate was 1.42 % found in Hou-Ping-Tao area, followed by 0.20 % in Chang-Tan-Li area, and the lowest was 0.15 % in the Wai-Mo-Shan area. Of the recaptured fish, 51 % were within 30 days after releaseing, 82 % within 60 days, and 93 %within 90 days. The longest period of liberty was 243 days. Most recaptures were found in 15 to 30 days after releasing. The highest recapture rate was 70.2 % for the Hou-Ping-Tao area, 42.7 % for the Chang-Tan-Li area, and the lowest 17.1 % for the Wai-Mo-Shan area. About 90 % of recaptures were within 4km from the release point, and the longest distance was 17.2km. Tagged fish released inside the bay almostly stay in the bay, but those released outside the bay move further away from release point. Tagged fish dispersed all directions, of which 48 % to the south-west, 20 % to the south and 15 % to the westward directions as orientated at the release point.