Acoustic Survey Of Irrawaddy Dolphin Populations In Chilika Lagoon: First Test Of A Compact High-Resolution Device
Acoustic Survey Of Irrawaddy Dolphin Populations In Chilika Lagoon: First Test Of A Compact High-Resolution Device
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DOI：
10.1109/oceansap.2006.4393872
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发表时间：
2006-05
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通讯作者：
R. Bahl;T. Ura;H. Sugimatsu;T. Inoue;T. Sakamaki;Junichi Kojima;Tomonari Akamatsu;H. Takahashi;S. Behera;A. Pattnaik;Muntaz Khan;S. Kar
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文献类型：
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作者：
R. Bahl;T. Ura;H. Sugimatsu;T. Inoue;T. Sakamaki;Junichi Kojima;Tomonari Akamatsu;H. Takahashi;S. Behera;A. Pattnaik;Muntaz Khan;S. Kar
伊洛瓦底海豚（Orcaella brevirostris）处于食物链的顶端，被认为是Chilika的旗舰物种。这些鲸类动物产生独特的回声定位脉冲，使它们在夜间或白天都能在声音上可见。声学测量方法是测量沿岸地区鼠海豚和海豚不可缺少的方法。本文报道了在Chilika首次采用声学测量技术的合作尝试，该技术基于一种创新的紧凑型便携式声学测量设备的设计，该设备专为观察小型鲸类群体而设计。声学传感器系统安装在一个“鸟笼”结构中，该结构包含3个水听器，形成一个主线性阵列，另外两个水听器与中央水听器形成一个小的3元三角形阵列，与线性阵列轴线垂直。它重25公斤，长3.6米，直径30厘米，可以用浮标和砝码垂直或水平部署。高速多通道数据采集系统记录所有水听器发出的海豚声。信号处理算法已被开发用于自动检测和区分来自其他水下声音的回声定位滴答声，声源的定位以及跟踪单个动物。该设备之前已经在准自然环境下的垂直模式下与一群宽吻海豚进行了测试，证实了它精确追踪几种发声动物的能力。海豚栖息地的奇里卡泻湖的深度可浅至1.5米。因此，该阵列必须以水平模式部署，这使得它能够在宽方向上提供非常好的横向分辨率。本文报道了在浅水条件下使用该阵列的第一个结果。几只伊洛瓦底海豚的活动被观察得非常清楚。
Irrawaddy dolphins (Orcaella brevirostris) being on top of the food chain are considered as a flagship species of Chilika. These cetaceans produce characteristic echolocation pulses that make them acoustically visible, night or day. Acoustic-based survey methods are found to be indispensable for surveying porpoises and dolphins in coastal precincts. This paper reports the first such collaborative attempt in Chilika by applying acoustic survey technology based on the design of an innovative compact and portable acoustic survey device designed for observation of groups of small cetaceans. The acoustic sensor system is housed in a "bird-cage" structure containing 3 hydrophones forming a main linear array, together with two more hydrophones forming a small 3-element triangle array with the central hydrophone, in a plane perpendicular to the linear array axis. It weighs 25 kg and is 3.6 m long, 30 cm in diameter, and can be deployed either vertically or horizontally with buoys and a weight. A high-speed multichannel data acquisition system records the dolphin click sounds from all hydrophones. Signal processing algorithms have been developed for automatic detection and discrimination of echolocation clicks from other underwater sounds, localization of sound sources, and tracking individual animals. The device has previously been tested in vertical mode in a quasi-natural environment with a group of bottlenose dolphins that has confirmed its capability to precisely track several vocalizing animals. The depth of the Chilika lagoon in the dolphin habitat can be as shallow as 1.5 m. Thus, the array has to be deployed in horizontal mode, which enables it to provide very good lateral resolution in the broadside direction. This paper reports the first results of using this array in shallow water conditions. Movements of several Irrawaddy dolphins have been observed very clearly.