Estimating North Pacific right whale Eubalaena japonica density using passive acoustic cue counting

TitleEstimating North Pacific right whale Eubalaena japonica density using passive acoustic cue counting
Publication TypeJournal Article
Year of Publication2011
AuthorsMarques, Tiago, Munger Lisa, Thomas Len, Wiggins Sean, and Hildebrand John
JournalEndangered Species Research
Volume13
Pagination163-172
EndNote Rec Number9889
Abstract

We present a method for estimating animal density from fixed passive acoustic detectors, and illustrate it by estimating the density of North Pacific right whales Eubalaena japonica in the areas surrounding 3 hydrophones deployed in the southeastern Bering Sea in 2001 to 2002 and 2005 to 2006. Input data were the distances to detected right whale calls, estimated using a normal mode sound propagation model, and call production rate, estimated from encounters by survey vessels with right whale groups. Given the scarcity of information about this highly endangered species, we also extrapolate our results to provide a tentative estimate of the total population size in shelf waters of the eastern Bering Sea. This gives a point estimate of 25 animals (CV 29.1%; 95% confidence interval 13–47), which agrees well with what little is known for this species. We discuss the assumptions underlying the method. Obtaining more reliable values requires a larger sample of randomly located hydrophones, together with improved estimates of call rate.