碩士 / 國立臺灣海洋大學 / 海洋事務與資源管理研究所 / 101 / Ecological risk assessment (ERA) has been applied on assessing the relative risk of bycatch species in recent years. ERA index is calculated by productivity of species and susceptibility to fisheries. In this study, two methods of assessments were used. For pelagic fishes, the ranking method was used to summarize the risks of overexploitation for 20 species in the Northwest Pacific Ocean. The susceptibility was culculated by the multiplication of the catchability, selectivity and post-capture mortolity. The results indicated the risks of sharks are higher than those of tunas and billfishes. The Shortfin mako (Isurus oxyrinchus), dusky shark (Carcharhinus obscurus) and bigeye thresher shark (Alopias superciliosus) have the highest risk. While the albacore tuna (Thunnus alalunga), yellowfin tuna (T. albacares) and striped marlin (Kajikia audax) have the lowest risk. For 11 shark species, the intrinsic population growth rate was used to culculate the productivity, and the susceptibility was the same as the first method. Four indices, ecological risk assessment, IUCN Red List, the trend of body weight, and the reflection point of population growth curve were used to conduct the integrated risk assessment. The results of cluster analysis and multi-dimensional scaling analysis indicated that the scalloped hammerhead (Sphyrna lewini) has the highest risk (group I), followed by the silky shark (C. falciformis) and spinner shark (C. brevipinna) (group II). The bigeye thresher and sandbar shark (C. plumbeus) fall in the group III. Group IV includes shortfin mako, pelagic thresher (A. pelagicus), oceanic whitetip (C. longimanus), dusky and smooth hammerhead (S. zygaena). A rigorous management measure is recommended for the scalloped hammerhead shark. Setting total allowable catch quota is recommended for those species in Group II and III. A consistent monitoring scheme is suggested for other species.
| Identifer | oai:union.ndltd.org:TW/101NTOU5277003 |
| Date | January 2013 |
| Creators | Lung-Hsin Huang, 黃隆鑫 |
| Contributors | Kwang-Ming Liu, 劉光明 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 80 |
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