| Summary: | 碩士 === 國立海洋大學 === 環境生物與漁業科學學系 === 91 === In the present study, the selectivity of gill nets and trammel nets for Kyphosus cinerascens and Kyphosus lembus were estimated from samples collected with nets of 7.8, 8.7,10.0, 10.8 ,12.5 cm(gill nets) and 10.4cm(trammel nets) mesh sizes. Sampling were caughted in the coral reef areas along the coast of Aodi in june and july of 2001 and 2002.
The 8.7 cm mesh size was the most efficient for two of the target species. IN gill nets , most fishes were caught by gilling or wedging. Other proportion, lowest and generally negligible in the gill net. But in trammel nets , most fishes were caught by tangled effects. From the fishes caught by all the gill nets and trammel nets , confirming the low selectivity of trammel nets.
Selectivity was assessed by three indirect model in this study. The estimated optimum selection lengths of Kyphosus cinerascens and Kyphosus lembus was separately between 22.6 and 37.1cm by all the mesh sizes . The selection factor of Kyphosus cinerascens is 2.90 ,and Kyphosus cinerascens is 2.97.
According to the results of the experiments, the catch efficiency will be better by gill net then by trammel net, if the mesh size is appropriate. But the catch of other species fishes will be more by thymmel net than by gill net.
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