FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

In this study, five gill nets mesh sizes (7.8, 8.7, 10.0, 10.8 and 12.5 cm) and one trammel net (inner 10.4 cm, outer 30.5 cm) were compared to estimate catching selectivity and efficiency for Kyphosus cinerascens and K. lembus along the coast of Auo-di from June to July in 2001 and 2002.Results showed that the 8.7 cm-mesh-size gill net was the most efficient net to catch that two species. In gill nets, mostly caught fishes were gilled or wedged. In the trammel net, fishes however were caught by tangling. This indicated that the trammel net was less selectivity on fish size.In addition, the selectivity of mesh size was assessed through Holt, Kitahara, and revised Sechin methods. The estimated optimum selection lengths of K. cinerascens and K. lembus were various from 22.6 to 37.1 cm, depending on mesh sizes. The selection factor for K. cinerascens was 2.90, and K. cinerascens was 2.97.The gill nets caught were target species than trammel net, but trammel net had more non-target species than gill nets. In IPUE analysis, the gill net with mesh size 8.7 cm has the highest income. The study suggested that gill net with mesh size 8.7 cm should be considered to use during the fishing season.