碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 99 / As the shark populations decline globally, shark management and conservation have become issues of great concern in recent years. Differentiate from conventional single species stock assessment, this study used an integrated risk assessment including four indices: ecological risk assessment, reflection point of population growth curve, IUCN endanger status, and the trend of body weight change to evaluate the risk of overexploitation for 11 pelagic shark species in the Northwest Pacific Ocean. The management recommendations were also provided. The shortfin mako shark had the highest ecological risk while the blue shark had the lowest. The position of the inflection point of the population growth curve indicated that the bigeye thresher had the highest risk while the blue shark had the lowest. The trend of body weight change showed that the scalloped hammerhead, dusky, and silky shark had the highest risk while the oceanic whitetip and blue shark had the lowest. The 11 shark species were categorized into three groups with an integrated ecological risk assessment using cluster analysis and multi-dimensional scaling analysis (80% similarity). The scalloped hammerhead, silky, and dusky shark have the highest risk of overexploitation, followed by the smooth hammerhead, oceanic whitetip, pelagic thresher, shortfin mako, spinner, bigeye thresher, and sandbar shark; the blue shark had the least risk of overexploitation. A management measure of complete ban fishing was recommended for the highest risk group; setting total allowable catch quota was proposed for the median risk group. Although no overexploitation was noted for the blue shark, a continuing monitoring was suggested to ensure the sustainable utilization of this species.
Keywords: Ecological Risk Assessment, sharks, stock assessment
| Identifer | oai:union.ndltd.org:TW/099NTOU5451027 |
| Date | January 2011 |
| Creators | Hsin-Jung Chan, 詹欣蓉 |
| Contributors | Kwang-Ming Liu, Shoou-Jeng Joung, 劉光明, 莊守正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 90 |
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