@article{fdi:010072437,
  title = {{C}ompensating for geographic variation in detection probability with water depth improves abundance estimates of coastal marine megafauna},
  author = {{H}agihara, {R}. and {J}ones, {R}. {E}. and {S}obtzick, {S}. and {C}leguer, {C}. and {G}arrigue, {C}laire and {M}arsh, {H}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he probability of an aquatic animal being available for detection is typically < 1. {A}ccounting for covariates that reduce the probability of detection is important for obtaining robust estimates of the population abundance and determining its status and trends. {T}he dugong ({D}ugong dugon) is a bottom-feeding marine mammal and a seagrass community specialist. {W}e hypothesized that the probability of a dugong being available for detection is dependent on water depth and that dugongs spend more time underwater in deep-water seagrass habitats than in shallow-water seagrass habitats. {W}e tested this hypothesis by quantifying the depth use of 28 wild dugongs fitted with {GPS} satellite transmitters and time-depth recorders ({TDR}s) at three sites with distinct seagrass depth distributions: 1) open waters supporting extensive seagrass meadows to 40 m deep ({T}orres {S}trait, 6 dugongs, 2015); 2) a protected bay (average water depth 6.8 m) with extensive shallow seagrass beds ({M}oreton {B}ay, 13 dugongs, 2011 and 2012); and 3) a mixture of lagoon, coral and seagrass habitats to 60 m deep ({N}ew {C}aledonia, 9 dugongs, 2013). {T}he fitted instruments were used to measure the times the dugongs spent in the experimentally determined detection zones under various environmental conditions. {T}he estimated probability of detection was applied to aerial survey data previously collected at each location. {I}n general, dugongs were least available for detection in {T}orres {S}trait, and the population estimates increased 6 +/- 7 fold using depth-specific availability correction factors compared with earlier estimates that assumed homogeneous detection probability across water depth and location. {D}etection probabilities were higher in {M}oreton {B}ay and {N}ew {C}aledonia than {T}orres {S}trait because the water transparency in these two locations was much greater than in {T}orres {S}trait and the effect of correcting for depth-specific detection probability much less. {T}he methodology has application to visual survey of coastal mega-fauna including surveys using {U}nmanned {A}erial {V}ehicles.},
  keywords = {{AUSTRALIE} ; {NOUVELLE} {CALEDONIE} ; {OCEAN} {INDIEN} ; {PACIFIQUE} ; {TORRES} {DETROIT} ; {MORETON} {BAIE}},
  booktitle = {},
  journal = {{PL}o{S} {O}ne},
  volume = {13},
  numero = {1},
  pages = {e0191476 [15 p.]},
  ISSN = {1932-6203},
  year = {2018},
  DOI = {10.1371/journal.pone.0191476},
  URL = {https://www.documentation.ird.fr/hor/fdi:010072437},
}