title: A multimodal detection model of dolphins to estimate abundance validated by field experiments.
abstract: Abundance estimation of marine mammals requires matching of detection of an animal or a group of animal by two independent means. A multimodal detection model using visual and acoustic cues (surfacing and phonation) that enables abundance estimation of dolphins is proposed. The method does not require a specific time window to match the cues of both means for applying mark-recapture method. The proposed model was evaluated using data obtained in field observations of Ganges River dolphins and Irrawaddy dolphins, as examples of dispersed and condensed distributions of animals, respectively. The acoustic detection probability was approximately 80%, 20% higher than that of visual detection for both species, regardless of the distribution of the animals in present study sites. The abundance estimates of Ganges River dolphins and Irrawaddy dolphins fairly agreed with the numbers reported in previous monitoring studies. The single animal detection probability was smaller than that of larger cluster size, as predicted by the model and confirmed by field data. However, dense groups of Irrawaddy dolphins showed difference in cluster sizes observed by visual and acoustic methods. Lower detection probability of single clusters of this species seemed to be caused by the clumped distribution of this species.
authors: National Research Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7 Hasaki, Kamisu, Ibaraki 314-0408, Japan. akamatsu@affrc.go.jp
authors: Tomonari
authors: T
authors: Akamatsu
authors: Tamaki
authors: T
authors: Ura
authors: Harumi
authors: H
authors: Sugimatsu
authors: Rajendar
authors: R
authors: Bahl
authors: Sandeep
authors: S
authors: Behera
authors: Sudarsan
authors: S
authors: Panda
authors: Muntaz
authors: M
authors: Khan
authors: S K
authors: SK
authors: Kar
authors: C S
authors: CS
authors: Kar
authors: Satoko
authors: S
authors: Kimura
authors: Yukiko
authors: Y
authors: Sasaki-Yamamoto
mesh_terms: D000162:Acoustics; D000465:Algorithms; D000818:Animals; D003463:Cues; D004289:Dolphins / Q000145:classification / Q000502:physiology* / Q000523:psychology; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D008386:Marine Biology / Q000379:methods*; D008962:Models, Theoretical; D009792:Oceans and Seas; D010699:Phonation; D011156:Population Density; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013045:Species Specificity; D014796:Visual Perception; D014828:Vocalization, Animal / Q000145:classification