| Summary: | 碩士 === 國立高雄海洋科技大學 === 漁業生產與管理研究所 === 97 === In order to reduce the high bycatch rate which influenced the fish resources around Kaoping Canyon waters caused by the shrimp beam trawls, it is necessary to modify the structure of fishing gear properly for fisheries management. This study was protocoled to attach both harden circle-frame with filter-rods and much smaller mesh of outer codend to the anterior of traditional codend for measuring the escape rate. Three intervals were introduced as 17mm, 19mm, and 21mm between the filter-rods in this study. In addition, the running-water tank was used to examine the survival rate of escaped fish in the experimental codend.
A total of 14 voyages, 70 experiments were carried out during this research period. The results indicated that the circle-frame put in transverse with filter-rods in 17mm, 19mm and 21mm intervals,the 17mm interval can reduce the fishes of bycatch as 92.04%,and target shrimp loss 33.08%；the 19mm can reduce the fishes of bycatch as 42.57%,and target shrimp loss 43.77%；the 21mm can reduce the fishes of bycatch as 57.00%,and target shrimp loss 11.32%. when the frame put in vertical with filter-rods in 17mm, 19mm and 21mm intervals, 17mm interval can reduce the fishes of bycatch as 67.46%,and target shrimp loss 2.21%；the 19mm can reduce the fishes of bycatch as 71.46%,and target shrimp loss 12.90%；the 21mm can reduce the fishes of bycatch as 59.58%,and target shrimp loss 1.82%.They also conducted the large size fish into upper codend and main target shrimp into inner codend. The escaped fish or shrimp moved into the upper codend had a higher survival rate while a lower rate occurred in outer codend.
Hence, using the circle-frame with put in vertical filter-rods in 17mm intervals the less of target shrimp is least and as the circle-frame with put in vertical filter-rods in 17mm intervals is reducing the 67.46％ bycatch rate.
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