碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 99 / This study analyzed stomach contents of four shark species, the shortfin mako (Isurus oxyrinchus), pelagic thresher (Alopias pelagicus), bigeye thresher (A. superciliosus), and scalloped hammerhead (Sphyrna lewini) caught by long-liners from northeastern Taiwan waters and landed at Nan Fan Ao fish market from Sep. 2009 to Jan. 2011. Their dietary compositions were analyzed and compared in relation to the body sizes, sexes, mature stages and seasons.
Total of 18 prey taxa were identified and indicated that dolphin fish (Coryphaena hippurus) was the most important food item (IRI%=59.4%) of the shortfin mako (55.4% of stomachs empty), and the followings were mackerels (Scomber spp.) and hair-tail fish (Trichiurus spp.). For the pelagic thresher, there were 49.3% stomachs empty, and a total of 26 prey taxa were identified and indicated that hair-tail fish was the most important food item (IRI%=91.71%). The next items were mackerels and Pacific pomfret (Brama japonica). There were 27 prey taxa identified and indicated that hair-tail fish was the most important food item (IRI%=59.4%) of the bigeye thresher (54.6% of stomachs empty), and the next items were oilfish (Lepidocybium flavobrunneum) and Pacific pomfret. For the hammerhead shark, there were 73.2% empty stomach, and a total of 16 prey taxa were identified and indicated that cephalopods were the most important food item (IRI%=29.72%). The next items were unidentified teleosts and mackerels.
The Pair-wise comparison was applied for different size classes, and dietary shift along with growth was detected. The dietary compositions were not significantly different between sexes for all four species. The dietary compositions were significantly different between immature and mature stages for all four species. And the dietary compositions were significantly different among seasons for I. oxyrinchus (summer/other seasons), A. pelagicus (spring/summer), A. superciliosus (winter/spring and summer), S. lewini (spring/autumn). Nevertheless, our study shows that the distinction of dietary compositions in different species also by fishing ground.
| Identifer | oai:union.ndltd.org:TW/099NTOU5451016 |
| Date | January 2011 |
| Creators | Wei-Lei, 賴衛 |
| Contributors | Shoou Jeng Joung, 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 | 121 |
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