Estimating the minimum numbers of calling mysticetes using passive acoustic bearings

Martin, S.B., J.J.-Y. Delarue, I.R. Urazghildiiev, B.J. Gaudet, E.T. Callaghan, K.R. MacDonald, J.E. Mills Flemming, and J.L. Miksis-Olds.

JASA Express Letters 6(8): 081201

DOI: 10.1121/10.0044581

Monitoring the abundance and distribution of marine mammals is essential for evaluating human and environmental effects. Passive acoustic monitoring offers a non-visual alternative, but estimating animal numbers remains difficult. We introduce Spatial Counting of Animal Numbers (SCAN), a method that counts unique bearings of detected calls to estimate a conservative minimum number of animals present. SCAN is a complementary metric to traditional presence/absence results and calibrated density estimates. The method is demonstrated using sei whale calls recorded by a four-element array on an autonomous glider. SCAN increases the information on marine mammal populations derived from passive acoustic recordings.