Estimating Florida manatee (Trichechus manatus latirostris) abundance using passive acoustic methods

T.A.M.’s contribution was conducted under the ACCURATE project, funded by the U.S. Navy Living Marine Resources program (Contract No. N3943019C2176) with partial support by CEAUL (funded by FCT— Fundação para a Ciência e a Tecnologia, Portugal, through the project UIDB/00006/2020).Manatees are difficult to detect, particularly cryptic populations that inhabit areas with limited water clarity. The effectiveness of using vocal detections to estimate manatee abundance was evaluated in a clear water spring where manatees congregate seasonally. Vocalizations were extracted by a detection classifier that clustered sounds with similar spectral properties. Vocalization counts from recordings in Blue Spring, FL, USA were strong predictors of manatee abundance. The link between independent visual counts and abundance estimates from passive acoustic monitoring was used to provide an estimate of 1.059 (95% confidence interval 0.963–1.127) vocalizations/manatee/5-min, which might be used elsewhere for cue counting of manatees.Publisher PDFPeer reviewe