A comparison of image and observer based aerial surveys of narwhal

Koen C. A. Broker*, Rikke G. Hansen, Kathleen E. Leonard, William R. Koski, Mads Peter Heide-Jorgensen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)
42 Downloads (Pure)

Abstract

From 25 to 30 August 2014 a double-observer line-transect survey was conducted over Melville Bay, home to one of two summering populations of narwhal (Monodon monoceros) off West Greenland. A total of 1,932 linear kilometers was surveyed along 33 transects. In addition to using observers, the aircraft was equipped with two oblique cameras to capture a comparable data set. Analysts reviewed the images for narwhal sightings, which were then matched to the observer sightings. The objectives of the study were to determine advantages and disadvantages of the detection capabilities of both methodologies, and to conduct a comparative analysis of population abundance estimates. Correcting for the truncated detection distance of the images (500 m), the image analysts recorded more sightings (62) and a lower mean group size (2.2) compared to aerial observers (36 and 3.5, respectively), resulting in comparable numbers of individuals detected by both platforms (135 vs. 126). The abundance estimate based on the image sightings was 2,536 (CV = 0.51, 95% CI: 1,003-6,406), which was not significantly different from the aerial observers estimate of 2,596 individuals (CV = 0.51; 95% CI: 961-7,008). This study supports the potential of using UAS for marine mammal abundance studies.

Original languageEnglish
Pages (from-to)1253-1279
Number of pages27
JournalMarine Mammal Science
Volume35
Issue number4
DOIs
Publication statusPublished - Oct-2019

Keywords

  • abundance estimation
  • aerial surveys
  • Arctic
  • Melville Bay
  • Monodon monoceros
  • narwhal
  • line-transect survey
  • strip census
  • unmanned aerial systems
  • West Greenland
  • UNMANNED AIRCRAFT SYSTEM
  • MONODON-MONOCEROS
  • MARINE MAMMALS
  • ESTIMATING ABUNDANCE
  • MELVILLE BAY
  • BAFFIN-BAY
  • VEHICLES
  • WHALES
  • WINTER
  • UAS

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