碩士 / 國立中山大學 / 海下科技暨應用海洋物理研究所 / 102 / Cetaceans is a kind of marine mammals that lives by sound, which uses high-frequency echolocation click to probe the environment, as well as uses low-frequency whistle to identify different individuals for social activities. However cetacean surveys are often limited by climate and depth of the coastal water , in order to compensate for the shortage of visual observation, this study used sonobuoy acoustic system to measure the whistle of Chinese White Dolphins, to observe its appearance in time and spatial distribution, and analyze the local ocean ambient noise. Three experiments were conducted at southern end of river mouth of Tadu River in July-August 2010, sonobuoys were deployed at different depth and distance from shore. Statistics of recorded whistles show 40% of appearance every hour, the main appearance time of white dolphins were 06:00~12:00 and 16:00~24:00. The activity range of white dolphins is 13m of depth (most frequently at 5m) and within 4.4km offshore. The foraging behavior of white dolphins was inferred by means of this activity model. In terms of tidal variance, white dolphins had different preferences for tidal activities according to the distances from shore observed from the three experiments, but their whistles centered from ebb to dry tide. For the ambient noise analysis of the habitat of white dolphins, the nighttime ambient noise was noisier than the daytime, which was probably caused by frequent night fishing and fish sounds. In addition, the far-shore ambient noise was noisier than the near-shore since most of fishing operations were far away from shore. Furthermore, it was found in the ship noise experiment conducted in the Kaohsiung Harbor that the noise generated by out board boats tended to shadow the whistles of white dolphins, approximately at 3-6 kHz, more likely than the noise generated by fishing boats. Nevertheless, the influence of noise on the activities of Chinese white dolphins is still uncertain so far. It was proved in this study that underwater acoustical measurements can be employed to establish references for future long-term research on Chinese white dolphin.
| Identifer | oai:union.ndltd.org:TW/102NSYS5281001 |
| Date | January 2013 |
| Creators | Jian-ming Liu, 劉建明 |
| Contributors | Ruey-Chang Wei, 魏瑞昌 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 86 |
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