title: Comparison of stationary acoustic monitoring and visual observation of finless porpoises.
abstract: The detection performance regarding stationary acoustic monitoring of Yangtze finless porpoises Neophocaena phocaenoides asiaeorientalis was compared to visual observations. Three stereo acoustic data loggers (A-tag) were placed at different locations near the confluence of Poyang Lake and the Yangtze River, China. The presence and number of porpoises were determined acoustically and visually during each 1-min time bin. On average, porpoises were acoustically detected 81.7+/-9.7% of the entire effective observation time, while the presence of animals was confirmed visually 12.7+/-11.0% of the entire time. Acoustic monitoring indicated areas of high and low porpoise densities that were consistent with visual observations. The direction of porpoise movement was monitored using stereo beams, which agreed with visual observations at all monitoring locations. Acoustic and visual methods could determine group sizes up to five and ten individuals, respectively. While the acoustic monitoring method had the advantage of high detection probability, it tended to underestimate group size due to the limited resolution of sound source bearing angles. The stationary acoustic monitoring method proved to be a practical and useful alternative to visual observations, especially in areas of low porpoise density for long-term monitoring.
authors.affiliation: Graduate School of Informatics, Kyoto University, Kyoto, Japan. sk0130@bre.soc.i.kyoto-u.ac.jp
authors.forename: Satoko
authors.initials: S
authors.lastname: Kimura
authors.forename: Tomonari
authors.initials: T
authors.lastname: Akamatsu
authors.forename: Kexiong
authors.initials: K
authors.lastname: Wang
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
authors.forename: Songhai
authors.initials: S
authors.lastname: Li
authors.forename: Shouyue
authors.initials: S
authors.lastname: Dong
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai
mesh_terms: D000162:Acoustics; D000819:Animal Communication; D000818:Animals; D019370:Observation; D019576:Porpoises; D014796:Visual Perception