Recommended snapshot length for acoustic point-transect surveys of intermittently available beaked whales

Details

• Journal Title:
  Journal of the Acoustical Society of America
• Personal Author:
  Barlow, Jay ; Trickey, Jennifer S. ; Schorr, Gregory S. ; Rankin, Shannon ; Moore, Jeffrey E.
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; SWFSC (Southwest Fisheries Science Center)
• Description:
  Acoustic point-transect distance-sampling surveys have recently been used to estimate the density of beaked whales. Typically, the fraction of short time “snapshots” with detected beaked whales is used in this calculation. Beaked whale echolocation pulses are only intermittently available, which may affect the best choice of snapshot length. The effect of snapshot length on density estimation for Cuvier's beaked whale (Ziphius cavirostris) is investigated by sub-setting continuous recordings from drifting hydrophones deployed off southern and central California. Snapshot lengths from 20 s to 20 min are superimposed on the time series of detected beaked whale echolocation pulses, and the components of the density estimation equation are estimated for each snapshot length. The fraction of snapshots with detections, the effective area surveyed, and the snapshot detection probability all increase with snapshot length. Due to compensatory changes in these three components, density estimates show very little dependence on snapshot length. Within the range we examined, 1–2 min snapshots are recommended to avoid the potential bias caused by animal movement during the snapshot period and to maximize the sample size for estimating the effective area surveyed.
• Keywords:
  Beaked Whales Marine Mammal Populations Beaked Whales Marine Mammal Populations
• Source:
  Journal of the Acoustical Society of America 149, 3830
• DOI:
  https://doi.org/10.1121/10.0005108
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:cb0cd4fc668e43f6f8e11e24787ba9808546ce53a58834db46eed987d1acfdce
• Download URL:
  https://repository.library.noaa.gov/view/noaa/45068/noaa_45068_DS1.pdf
• File Type:
  [PDF - 2.00 MB ]