| Project/Area Number |
60480068
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Ocean Research Institute, University of Tokyo |
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Principal Investigator |
TANAKA Syoiti Ocean Research Institute, University of Tokyo, 海洋研究所, 教授 (90013549)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAISHI Manabu Ocean Research Institute, Univeristy of Tokyo, 海洋研究所, 教務職員 (00126088)
TATSUKAWA Ken-ichi Ocean Research Institute, University of Tokyo, 海洋研究所, 助手 (20013584)
MOGI Masako Ocean Research Institute, University of Tokyo, 海洋研究所, 助手 (20013568)
ISHII Takeo Ocean Research Institute, University of Tokyo, 海洋研究所, 教授 (80013564)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1986: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1985: ¥4,300,000 (Direct Cost: ¥4,300,000)
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| Keywords | Computer program / Stock assessment / Fishery management / Fishery forecast / Catch limit / Small type trawl fishery / ミンククジラ |
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| Research Abstract |
The purposes of this project are firstly to develop a computer program for assessment, forecast and management of fish stocks and secondly to explore new management procedures which require minimum information.
1. The computer program consists of two parts. One is for assessment of present status of the stock and the other is for forecasting changes of the stock and fishing industry after enforcement of regulation measures. Management policy is evaluated by seven variables including catch in weight and value, added value per person. Data obtained from small type trawl fishery in Niigata Prefecture are analysed by this computer program. It is found that both of two flat fish species (hirame and magarei) are heavily overfished. Mesh size regulation is not effective. Engine power regulation is useful but provides different effect for each of the boat size categories.
2. A practical and simple management procedure is proposed. Catch limit Y is calculated by <Y_(t+1)> = <Y_t> (1+h( <P_t> - <P_U> )/ <P_U> +g <delto> <P_t> / <P_t> ), where <P_t> and <delta> <P_t> are stock level in year t and their difference, <P_U> is the target stock level, and g and h are constants. Only necessary information for operating this procedure is a relative index of stock size. Computer simulations proved that this procedure provides very stable management under fairly high estimation error in <P_t> if g and h are given properly. A procedure to adjust <P_U> toward the MSY level is added to the system and it is found effective.
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