• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.271-282
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• 2021

This study aims to understand the opening efficiency of the finless porpoise escape guide net by the type of extension net that is the part to which the escape guide net is attached in stow net. To this end, extension nets were manufactured in full size and the net mouth area and towing tension were investigated according to the towing speed (0.2, 0.4, 0.6 and 0.8 m/s) and the type of extension net (25 mm net and raschel net) in the water tank. As a result, the net mouth area of the guide net was larger when the raschel net was used for the extension net than when the 25 mm net was used under all towing speeds. In addition, regardless of the type of extension net, the net mouth area reached about 80% of the maximum value at a towing speed of 0.4 m/s. In the field, fishing operation of stow net is performed only when the current speed is above 0.4 m/s. Therefore, the speed of 0.4 m/s was confirmed as a meaningful value to determine whether it is possible to operate. As a result of analyzing the relationship between the net mouth area of the guide net and the towing tension, it was confirmed that the difference in the net mouth area of the guide net according to the type of the extension net was due to the difference in the solidity ratio.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.9-16
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• 2005

This study was conducted in order to improvement of fishing gear and fishing operating system for anchovy boat seine by labor saving improved nets. Field experiments were carried out observe geometry of nets and fishing operating system by catcher boats. The obtained results are summarized as follows : The Vertical net opening of fore wing net, wing net, inside wing net, square, fore bag net, flapper, after bag net of the labor saving improved net according to the distance between catcher boats were varied in the range of 5.0${\sim}$7.8, 14.4${\sim}$21.1, 16.2${\sim}$21.2, 14.0${\sim}$17.3, 11.7${\sim}$13.9, 5.4${\sim}$6.9, 8.2${\sim}$9.8m respectively, varied in the range of 50${\sim}$78, 25${\sim}$36, 24${\sim}$31, 31${\sim}$38, 61${\sim}$73, 71${\sim}$91, 87${\sim}$104% of the actual ratio of net opening in each part. Labor saving improved net was performed instant net opening in fore wing net and maintained stable net opening and towing depth by means of attached net pendant. Also, it was minimized as net pocket phenomenon leading to guide anchovy for more catch by means of attached body net. The opening in accordance with distance between catcher boats and towing speed. The catch of labor saving improved net was increased than traditional net due to decrement of net resistance by improvement of bag net leading to increasement of towing speed and reduction of escape anchovy as well as improve nets of whole operation system.