The Northwest Atlantic population of blue whales Balaenoptera musculus is endangered. Understanding their habitat use off eastern Canada is important for protection and recovery. Passive acoustic monitoring (PAM) has contributed to identifying areas of importance to this population, which include deep slope waters along the edge of the Scotian Shelf off Nova Scotia. Many PAM studies have focused on assessing blue whale acoustic occurrence using infrasonic (A, B, AB) calls, which are produced by males and associated with reproduction or migration. Audible (D, downsweep, arch) calls are less well described but are produced by both sexes and may serve social or foraging functions. We analyzed PAM data collected from Emerald Basin on the central Scotian Shelf from 2015 to 2019 to assess on-shelf blue whale acoustic presence and whether audible calls would contribute to our understanding of their presence. Calls occurred on 39% of recording days, representing year-round presence, with the highest acoustic occurrence observed between September and January (calls occurring on 17-100% of days per month). Of days with calls, 25% of those days contained only infrasonic calls, and 41% contained only audible calls, indicating that blue whale presence would have been underestimated if only infrasonic calls were monitored. These results suggest that Emerald Basin may also be important habitat for blue whales in Atlantic Canada. We recommend that future acoustic studies incorporate both infrasonic and audible call types, as well as further investigation of the Scotian Shelf as potential important habitat.
原文链接
分享
引用
