Spatio-temporal distribution of beaked whales on Canada’s East Coast

Abstract

Beaked whales represent some of the least understood marine mammals worldwide with the movements and distribution of many species largely unknown. Around eastern Canada current knowledge is limited to the eastern Scotian shelf and northern bottlenose whales. The acoustic signals of the beaked whale species are recognizable and sufficiently unique to be candidates for passive acoustic monitoring. Thirteen deep-water recorders located along the shelf break off Eastern Canada from Bonnécamps Canyon (42.5 N) to Southern Labrador (55.3 N) collected acoustic data near-continuously from Aug 2015 to July 2016. A minimum of one of every 20 minutes were recorded at 250,000 samples per second to monitor for the presence echolocations clicks of odontocetes, including beaked whales. An automated detector, validated by manual analysts, identified the presence of endangered Northern Bottlenose whales (Hyperoodon ampullatus), Cuvier’s (Ziphius cavirostris), and special concern Sowerby’s beaked whales (Mesoplodon bidens). The presence data were analyzed to determine the occurrence and residency durations of beaked whales throughout the geographic range studied. We then studied the influence of currents, sea ice, surface temperatures, chlorophyll, distance to the 1000 m isobath, background noise and anthropogenic noise on the whales’ acoustic occurrence. Acoustic studies such as this allow us to gain further insights on the occurrence of these notoriously difficult to study species.