Improving population estimates by quantifying diving and surfacing patterns: a dugong example

Hagihara, Rie, Jones, Rhondda E., Grech, Alana, Lanyon, Janet M., Sheppard, James K. and Marsh, Helene (2014) Improving population estimates by quantifying diving and surfacing patterns: a dugong example. Marine Mammal Science, 30 1: 348-366. doi:10.1111/mms.12041

Author Hagihara, Rie
Jones, Rhondda E.
Grech, Alana
Lanyon, Janet M.
Sheppard, James K.
Marsh, Helene
Title Improving population estimates by quantifying diving and surfacing patterns: a dugong example
Journal name Marine Mammal Science   Check publisher's open access policy
ISSN 0824-0469
Publication date 2014-01-01
Year available 2013
Sub-type Article (original research)
DOI 10.1111/mms.12041
Open Access Status Not yet assessed
Volume 30
Issue 1
Start page 348
End page 366
Total pages 19
Place of publication Hoboken, NJ, United States
Publisher Wiley-Blackwell Publishing
Language eng
Formatted abstract
Diving animals are available for detection from above the water when environmental conditions are favorable and the animals are near the surface. The number of animals that are unavailable for detection needs to be estimated to obtain unbiased population estimates. The current availability correction factors used in aerial surveys for the dugong (Dugong dugon) allow for variation in environmental conditions but use the average time dugongs spend near the surface (i.e., constant availability corrections). To improve availability estimates, we examined location and dive data from nine dugongs fitted with satellite telemetry units and time-depth recorders (TDRs) in eastern Australia. The effects of water depth, tidal conditions, and habitat types on dugong surfacing time were examined using generalized linear mixed models (GLMMs). We found that availability for detection differed with water depth, and depth-specific availability estimates were often lower than the constant estimates. The habitat effect was less influential, and there was no tidal effect. The number of dugongs estimated using depth-specific availabilities were higher than those obtained using constant availabilities across water depth. Hence, information on water depth can refine availability estimates and subsequent abundance estimates from dugong aerial surveys. The methodology may be applicable to other aquatic wildlife.
Keyword Abundance estimation
Aerial survey
Availability bias
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online 7 May 2013

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biological Sciences Publications
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