Kimura Satoko, Akamatsu Tomonari, Dong Lijun, Wang Kexiong, Wang Ding, Shibata Yasutoki, Arai Nobuaki
Graduate School of Informatics, Kyoto University, Yoshidahon-machi, Sakyo-ku, Kyoto, 606-8501, Japan.
National Research Institute of Fisheries Engineering, Fisheries Research Agency, Hasaki, Kamisu, Ibaraki 314-0408, Japan.
J Acoust Soc Am. 2014 Jun;135(6):3364-70. doi: 10.1121/1.4875710.
Passive acoustic monitoring for cetaceans mainly employ fixed-location methods or point transect samplings; an acoustic survey from a moving platform to conduct line transects is less common. In this study, acoustic capture-recapture by combining a double-observer method with line transect sampling was performed to observe Yangtze finless porpoises. Two acoustic devices were towed with the distance between them varying 0.5 to 89.5 m. The conditional probabilities that both devices would detect the porpoises within the same time window were calculated. In a 1-s time window, it became smaller as the distance between the devices increased, approaching zero when the distance between them was more than 50 m. It was considered that the devices with less than 50 m distance detected the same signals from the same animals, which means the identical detection. When the distance between them is too great, the recapture rate is reduced and the incidence of false matching may increase. Thus, a separation distance of around 50 m between two devices in acoustic capture-recapture of Yangtze finless porpoises was recommended. Note that the performance of the double detections can change depending on the particular device used and on animal behaviors such as vocalizing interval, ship avoidance.
对鲸类动物的被动声学监测主要采用固定位置方法或点断面抽样；通过移动平台进行声学测量以开展线断面抽样的情况较少见。在本研究中，结合双观察员方法与线断面抽样进行声学捕捉-重捕，以观察长江江豚。拖曳两个声学设备，它们之间的距离在0.5至89.5米之间变化。计算两个设备在同一时间窗口内都检测到江豚的条件概率。在1秒的时间窗口内，该概率随着设备间距离的增加而变小，当它们之间的距离超过50米时接近零。认为距离小于50米的设备检测到来自同一动物的相同信号，即相同检测。当它们之间的距离过大时，重捕率降低，误匹配发生率可能增加。因此，建议在长江江豚的声学捕捉-重捕中，两个设备之间的间隔距离约为50米。请注意，双重检测的性能可能会因所使用的特定设备以及诸如发声间隔、避船等动物行为而有所变化。
