title: Calibrating passive acoustic monitoring: correcting humpback whale call detections for site-specific and time-dependent environmental characteristics.
abstract: This paper demonstrates the importance of accounting for environmental effects on passive underwater acoustic monitoring results. The situation considered is the reduction in shipping off the California coast between 2008-2010 due to the recession and environmental legislation. The resulting variations in ocean noise change the probability of detecting marine mammal vocalizations. An acoustic model was used to calculate the time-varying probability of detecting humpback whale vocalizations under best-guess environmental conditions and varying noise. The uncorrected call counts suggest a diel pattern and an increase in calling over a two-year period; the corrected call counts show minimal evidence of these features.
authors.affiliation: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0701 thelble@ucsd.edu, gdspain@ucsd.edu, gscampbell@ucsd.edu, jahildebrand@ucsd.edu.
authors.forename: Tyler A
authors.initials: TA
authors.lastname: Helble
authors.forename: Gerald L
authors.initials: GL
authors.lastname: D'Spain
authors.forename: Greg S
authors.initials: GS
authors.lastname: Campbell
authors.forename: John A
authors.initials: JA
authors.lastname: Hildebrand
mesh_terms: D000162:Acoustics; D000818:Animals; D002138:Calibration; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards; D050640:Humpback Whale / Q000502:physiology*; D008962:Models, Theoretical; D009038:Motion; D009624:Noise, Transportation; D009792:Oceans and Seas; D011312:Pressure; D012767:Ships; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014828:Vocalization, Animal / Q000145:classification*; D014867:Water
chemical_list: D014867:Water