THE INFLUENCE OF CATCH VOLUME ON TRAWLER WARP TENSION

어류가 대량으로 입강했을 때의 선미 trawl의 warp 장력

Few reports have been written regarding the measurement of stern trawler warp tension under conditions of a full catch. This report compares the tension imposed on the warps at the time the boat begins to tow the net and the tension at the time the cod end is filled with a large quantity of fish. The structure of the otter boards and trawl net used for the experiment was the same types as used by Koyama, Sakurai, and Sumikawa (1968). The warp tension was measured with a load cell tension meter. 3) This meter continuously records the tension on a pen oscillograph. The net towing speed was measured with the CM-lA type current meter, Toho Dentan Co. Ltd., Japan. The data collected in the experiment are shown in Table 1. This table indicates that shooting No. 2 and No. 11 show a large catch volume, and the types of fish caught are shown in Table 2. The tension meter recordings when the boat began to tow the net and when the cod end was filled with a large quantity are shown in Fig. 1 and Fig. 2. It is indicated that the barracouta Thyrsites atun (EUPHRASEN) causes little tension difference between the time before they enter the net and the time after they enter the net before hauling. Other types of fish influence tension similarly. According to these results, the warp tension measurements as recorded on a big stern trawler are more influenced by rough sea wave action than by the volume of fish caught.

(1) 1968년 6월 18일부터 7월 16일 사이에 일본수산청 어업조사선 Kaiyo-Maru에 승선 New Zealand 근해에서 trawl 실험을 행하였다. (2) 대형선미 trawl에 있어 예강초와 양강직전의 warp 장력간의 차는 입강어의 다과와는 상관이 없는 것 같다.