Annual logbook catch data of the Hsinshefar and Chiafong fishing grounds from 1996 to 2003 were analysed to assess spatial variation in species composition. Most of the catch comprised pelagic migratory species in the two fishing grounds. Sarda orientalis, Auxis rochei and trichiurus lepturus were the important dominant species at the Hsinshefar fishing ground, while Auxis thazard, Decapterus kurroides and Auxis rochei were the important dominant species at Chiafong fishing ground. CPUE of the Hsinshefar was greater than that of Chiafong in all years except 1997. Main fishing season is the same in Spring. There were 122~ 172 species caught by set-net, average is 143, and the diversity index (H') was 1.17~1.52, index of evenness (J') was 1.23~1.52 at Hsinshefar and 99~ 162 species were caught, average is 131, diversity index (H') was 1.16~1.63, index of evenness (J') is 1.20~1.63 at Chiafong fishing ground. Annual mean production of the dominant species were comprised 82.53% (77.05% ~87.21%) at Hsinshefar and 82.46% (78.35 ~ 87.32%) of total yearly catch at Chiafong fishing ground. There was significantly different (p<0.05) with monthly average catch species between two fishing grounds. There are 14 same dominant species, including 6 species of Scombridae, 3 species of Carangidae and 5 other species that they are most of migratory species in the two fishing grounds.
Annual logbook catch data of the Hsinshefar and Chiafong fishing grounds from 1996 to 2003 were analysed to assess spatial variation in species composition. Most of the catch comprised pelagic migratory species in the two fishing grounds. Sarda orientalis, Auxis rochei and trichiurus lepturus were the important dominant species at the Hsinshefar fishing ground, while Auxis thazard, Decapterus kurroides and Auxis rochei were the important dominant species at Chiafong fishing ground. CPUE of the Hsinshefar was greater than that of Chiafong in all years except 1997. Main fishing season is the same in Spring. There were 122~ 172 species caught by set-net, average is 143, and the diversity index (H') was 1.17~1.52, index of evenness (J') was 1.23~1.52 at Hsinshefar and 99~ 162 species were caught, average is 131, diversity index (H') was 1.16~1.63, index of evenness (J') is 1.20~1.63 at Chiafong fishing ground. Annual mean production of the dominant species were comprised 82.53% (77.05% ~87.21%) at Hsinshefar and 82.46% (78.35 ~ 87.32%) of total yearly catch at Chiafong fishing ground. There was significantly different (p<0.05) with monthly average catch species between two fishing grounds. There are 14 same dominant species, including 6 species of Scombridae, 3 species of Carangidae and 5 other species that they are most of migratory species in the two fishing grounds.