Research Document 2020/073
Narwhal (Monodon monoceros) abundance estimate from the 2018 aerial survey of the Northern Hudson Bay population
By Watt, C.A., Hornby, C., and Hudson, J.
Abstract
Northern Hudson Bay narwhal (Monodon monoceros) form a distinct genetic and geographically isolated population. Visual aerial surveys were conducted from 3–14 August 2018 in order to estimate the abundance of this narwhal population. This survey was designed to repeat the 2011 survey design, with one change to increase coverage in Wager Bay, as recommended by the Arviq Hunters and Trappers Organization in Naujaat. The survey covered four key areas commonly used by narwhal: Wager Bay, Roes Welcome Sound, Repulse Bay and the northern bays of Gore Bay and Lyon Inlet. The surface abundance estimate for narwhal was 5,055 (CV = 0.270) individuals. After adjustment for availability bias to account for whales not seen due to diving (adjustment factor Ca = 2.80 [CV = 0.05]) and perception bias, which occurs when some observers miss whales (adjustment factor Cp = 1.36 [CV = 0.092]), the estimated adjusted abundance is 19,232 (CV = 0.278, 95% CI = 11,257–32,856) narwhals.
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