The presence of large whale species in Clayoquot Sound and its offshore waters

Burnham, R.E., D.A. Duffus, and X. Mouy

Continental Shelf Research 177: 15–23 (2019)

DOI: 10.1016/j.csr.2019.03.004

Large whale populations in the northeast Pacific were severely reduced by whaling, with many showing limited recovery. Their use of offshore waters and limited knowledge of life histories has hindered studies focused on estimating population numbers and mapping habitat use. Acoustic recordings, using vocalizations as a marker of whale presence, may be the first step in re-establishing baseline knowledge of species presence over time and space. Recordings from both stationary and mobile platforms, covering waters from coastal to shelf-break and offshore waters, show spatial segregation in the dominant species recorded. Inshore recordings are dominated by more coastally-focused species, whereas fin (Balaenoptera physalus) blue (Balaenoptera musculus) and sperm whales (Physeter macrocephalus) are primarily heard in the shelf-break zones. Calls tentatively described for sei whales (Balaenoptera borealis) are also noted. Calls matching those previously described to these species as breeding and foraging calls were found. Acoustic monitoring surveys like this study are needed to better map presence and habitat use of these rare and endangered species, ultimately leading to the identification and protection of areas important to population recovery.