2001 Fiscal Year Final Research Report Summary
Optimal Fishing Policy for Species Replacement
| Project/Area Number |
10660174
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General fisheries
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
MATSUDA Hiroyuki Ocean Research Institute, The University of Tokyo, Associate Professor, 海洋研究所, 助教授 (70190478)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TATSUKAWA Ken-ichi Ocean Research Institute, The University of Tokyo, Research Assistant, 海洋研究所, 助手 (20013584)
KATSUKAWA Toshio Ocean Research Institute, The University of Tokyo, Research Assistant, 海洋研究所, 助手 (90302679)
MATSUMIYA Yoshiharu Ocean Research Institute, The University of Tokyo, Professor, 海洋研究所, 教授 (10100885)
|
|---|
| Project Period (FY) |
1998 – 2001
|
| Keywords | stock fluctuation / risk assessment / strong year class / resource management / immature fish / Beyerton-Holt model |
|---|
| Research Abstract |
Many fisheries have alternative target stocks and selectively exploit the one with the highest expected income. Although target switching is very common in practice, few attempts have thus far been made to study target switching. In this paper, we investigated the potential effects of target switching on the yield and sustainability of fish stocks. We simulated switching exploitation between two independent stocks, using a delay-difference model. Our study revealed that well-planned target switching increases yields and simultaneously decreases the risk of the stocks collapsing. Target switching decreases fishing pressure on the less abundant stock and helps the declined stock to recover. Therefore, the minimum stock level is increased by switching. As switching keeps both stocks at productive levels, the total yield is increased by switching. Target switching is effective, especially when the catchability increases with the depletion of a stock population. Target switching depends on the availability of information on stock abundance. Thus, we examined the vulnerability of switching to stock assessment errors. If the stock assessment is very uncertain, then little or no switching is recommended. Target switching can have substantial effects on fisheries. Therefore, we must investigate the mechanisms of switching and incorporate switching into management plans.
|
