• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.15-23
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• 1984

Difference of the entering and the escaping behaviour of shrimp(Palaemon pacificus) to the model traps were observed in accordance with netting materials, baits, type of traps and slope of flapper, and gathering responses were also investigated on the odour of bait extracts in the aquarium as the preliminary test. In order to investigate the difference in catch according to type and structure of traps those designated from A to E were made of iron frames and nettings. The type A was a conical shape with two entrances at its both sides and the others were square piller shape with one entrance at their upper surface(type B) or two entrance at their both ends(type C, D and E). However th type D and E were connected with flapper and the thye E was made by attaching iron frames of same height under the type D. The traps were prepared 10 each and so a total of 50 traps were used in the experiment at sea. The main species caught was Charybdis japonica, but Astroconger myriaster was also caught fairly. The catches of these species were significant in difference between the types of traps. That is, Charybdis japonica was caught more in type A, C and D than others and less in type B and E, and Astroconger myriaster was caught more in type A and D and less in type B and E. However the catch of Astroconger myriaster in type C, even if less than that in type A showed no significant difference with the other traps. The total catch of Charybdis japonica and Astroconger myriaster was almost same in order with the catch of Charybdis japonica. The type B and E seemed to be difficult in entering of fishes into them. However, the type A and C seemed to be easy not only in entering, but also in escaping. Especially, the type C showed more escaping. On the other hand, the type D seemed to be not so easy in entering of fishes as type A and C, but very difficult in escaping. Consequently, the escaping of fishes from the traps seemed to be more difficult in conical traps than any other traps. The catches might be influenced by the bait with bag compare to without bag and also the immersed time of traps into water for fishing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.268-281
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• 2004

A study was carried out in order to estimate the deformation of the pound net according to the current by the model test in the circulating water channel. The tension of the frame rope and the variation of net shape were measured to investigate the deforming of the model pound net in the flow. The results are obtained as follows; 1. The experimental equation between tensions (R) of the frame rope and velocity (ν)was found to be R=$19.58v^{1.98}$($r^2$=0.98) in case of the upperward flow with fish court net and R=$26.90v^{1.72}$($r^2$=0.95)at the upperward flow with bag net according to the velocity from 0.0m/s to 0.6m/s, respectively. 2. As the variation of flow speed inside of the model net was gradually decreased according as which is passed through netting panels, in case of the upperward flow with fish court net, the flow speed was about 70% of initial flow speed at 0.1m/s, 60% at 0.2m/s, 50% at 0.3m/s and 40% 0.4~0.6m/s at the measurement point(h) inside of the first bag net, respectively. In case of the upperward flow with bag net, as the flow speed was steeply decreased according as which if passed through the second bag net, it was 30~60% of the initial flow speed and was 20~30% inside of the first bag net and was about 10~20% inside of the inclined passage net. 3. In case of the upperward flow with fish court net, the variation of deformed angle of fish court net was from 0$^{\circ}$ to 70$^{\circ}$and that of inclined passage net was from 0$^{\circ}$ to 63$^{\circ}$and that of the second bag net was from 0$^{\circ}$ to 47$^{\circ}$ . 4. In case of the upperward flow with fish court net, the variation of deformed angle of the second bag net was changed from 0$^{\circ}$ to 70$^{\circ}$and that of the inclined passage net was from 0$^{\circ}$ to 55$^{\circ}$ and that of the fish court net was from 0$^{\circ}$ to 50$^{\circ}$. The depth ratio of the first bag net was changed from 0% to 35% and that of the second bag net was from 0% to 20% and that of the inclined passage net was from 0% to 35%. In the flow speed 0.5m/s, the inclined passage net was raised up to the entry of the bag net and then prevented it more over 90%. 5. To be increased the opening volume of pound net, it needs to attach the added weight outside of the fish court net, inclined passage net and bag net. At the same time, it needs to adjust the tension of the twine for maintenance of the shape.