title: Acoustic capture-recapture method for towed acoustic surveys of echolocating porpoises.
abstract: 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.
authors.affiliation: Graduate School of Informatics, Kyoto University, Yoshidahon-machi, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Kimura
authors.affiliation: National Research Institute of Fisheries Engineering, Fisheries Research Agency, Hasaki, Kamisu, Ibaraki 314-0408, Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Akamatsu
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Dong
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China.
authors.forename: Kexiong
authors.initials: K
authors.lastname: Wang
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China.
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
authors.affiliation: Tohoku National Fisheries Research Institute, Fisheries Research Agency, Same-machi, Aomori, 031-0841, Japan.
authors.forename: Yasutoki
authors.initials: Y
authors.lastname: Shibata
authors.affiliation: Field Science Education Research Center, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000818:Animals; D004455:Echolocation; D004784:Environmental Monitoring / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D009038:Motion; D011156:Population Density; D019576:Porpoises / Q000145:classification / Q000502:physiology*; D011312:Pressure; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014160:Transducers, Pressure; D014796:Visual Perception; D014828:Vocalization, Animal / Q000145:classification; D014867:Water
chemical_list: D014867:Water