Utilization Mechanism of Fisheries Information in Far-seas Skipjack Purse Seine

Research Project

Project/Area Number	63560185
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	General fisheries
Research Institution	TOKYO UNIVERSITY OF FISHERIES
Principal Investigator	TAKEUCHI Shoichi Tokyo Univ.of Fisheries, Professor, 水産学部, 教授 (00017047)
Co-Investigator(Kenkyū-buntansha)	KOIKE Takatomo Tokyo Univ.of Fisheries, Associate Professor, 水産学部, 助教授 (10017048) 小倉通男東京水産大学, 水産学部, 教授 (60017035)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥2,500,000 (Direct Cost: ¥2,500,000) Fiscal Year 1989: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
Keywords	purse seine / fisheries information / fish detection / skipjack / catchability / データベース
Research Abstract	In the far-seas skipjack purse seine fisheries, the numerous efforts are made on the locating of fishing ground, for the purpose of fish detection. The aim of this research project is the analysis on the utilization of fisheries information which is the decision factor for the fish detection in the fishing ground, and the evaluating of the fish amount, as well as the theory for attitude and behavior of purse seiner on moving to another fishing ground. The data on the fisheries information was collected by means of the on-board survey during the cruise of porse seiner. The information could be divided into two categories; macro and micro aspects. The macro aspects for fish detection mean the locating of fishing ground by use of radio communication with other vessels, the records of own past cruise and the position locating of the drifting timbers attached with the radio buoy. In the micro aspects, the observation from the bridge or crow's nest is effective to find out the flock of sea bi … More rds. In this case, after approaching to the position of sea birds flocking, the sonar scanning is conducted to evaluate the fish amount so as to decide the propriety of the fishing operation. On the effectiveness of radio communication and the navigation method for the fish detection, the data were also collected for the further analysis. The influence of the vessel size was also investigated, from the view point of catchability of purse seiner. After the enforcement of the new version for the tonnage measuring unit of vessel size, the far-seas skipjack purse seiner was regulated to be less than 351GT, and greater than or equal to 200GT, in the central area of Pacific Ocean. According to the new measuring unit, the re-modeled vessels are tended to be equipped with the larger fish-hold which may affect the operation theory in the purse seiner. With the catch data obtained at Yaizu port of Shizuoka Prefecture, the influence of re-modeling on the catch amount was analyzed in relation to the vessel's behavior. The re-modeled vessel with the larger fish-hold increased the number of operations, operating days and cruising days, while no change was observed on the catch amount per operation and per hauling as well. The effect of remodeling in vessel size was obtained as the increase of the yearly cruising number and yearly catch amount in the case of good catch condition. Concerning the fish detection by the binoculars observation on the bridge, the vibration near the wheelhouse may result into the lower ability for fish detection. According to the measurement of the vibration for the newly built purse seiner, the vibration of this vessel is considered not to affect the observation ability. Less