Fin Whale Call Presence and Type Used to Describe Temporal Distribution and Possible Area Use of Clayoquot Sound

Abstract

Passive acoustic recordings can identify whale species presence and behaviour in an area over time. Here a combination of moored and mobile receivers were used for acoustic surveillance of the deep-coastal and offshore waters of Clayoquot Sound, off the west coast of Vancouver Island. This study adds to the acoustic record of fin whale (Balaenoptera physalus) presence in the Canadian Pacific. Whale calls are a proxy for presence, and call type is an indicator of behaviour and habitat use. The recordings suggest a change in behaviour and social context of whales in this area as winter progresses to spring. There is a distinct temporal separation in call type used by fin whales, whereby recordings taken between December and late February are dominated by the 20-Hz pulse, while the 40-Hz call is prevalent in early spring (March–April). The presence of doublet song sequences is also noted for the winter recordings. The use of 20-Hz song sequences and 40-Hz calls suggest this area is used for both breeding and feeding behaviours. For 40-Hz especially, the calls are most frequently recorded along the continental shelf break, and areas of topographical complexity that may entrain prey. This study adds to the little that is known of fin whale presence and use of this area. Further works will continue to add to our knowledge of distribution and habitat use of fin whales in the northeastern Pacific as populations recover from whaling.