Roanan DeMeyer

Topic

Insights into Cetacean Habitat Use in British Columbia Using Visual and Acoustic Methods

Department of Geography

Date & location

• Wednesday, June 19, 2024

• 2:00 P.M.

• David Turpin Building

• Room B215

Reviewers

Supervisory Committee

• Dr. David Duffus, Department of Geography, University of Victoria (Co-Supervisor)

• Dr. Rianna Burnham, Department of Geography, UVic (Co-Supervisor)

• Dr. Lynn Lee, Parks Canada, UVic (Non-unit Member) 

External Examiner

• Dr. Ross Chapman, School of Earth and Ocean Sciences, University of Victoria 

Chair of Oral Examination

• Dr. Sheila Rabillard, Department of English, UVic

   

Abstract

Cetaceans play critical roles in marine ecosystems as top predators and ecosystem engineers. However, the current ecological role, distribution, and abundance of cetaceans is influenced by a legacy of industrial whaling. While this threat no longer exists in British Columbia (BC), Canada, cetacean populations in these waters face contemporary threats such as vessel noise, ship strikes, entanglements, and pollution. Protecting recovering cetacean populations requires knowledge of their habitat use patterns to inform effective management. In this thesis, I use visual and acoustic methods to contribute to the historical and current knowledge of cetacean habitat use in BC’s waters. The visual data were gathered via transect line surveys offshore of Clayoquot Sound, BC, between 1993 and 2007. I use these data as a baseline to provide historical context to more recent studies and spatial comparisons with studies from adjacent regions. The acoustic data were gathered from two hydrophones deployed in Gwaii Haanas National Park Reserve, National Marine Conservation Area Reserve, and Haida Heritage Site on the east and west coasts of Haida Gwaii from August 2018 to August 2019. Manual analysis of these data focused on the identification of cetacean call presence, and also noted vessel noise. Species habitat use was inferred using call timing and known behavioural associations of call types. The frequency range of the loudest identified vessel noise was measured and classified into small and large size classes. Vessel frequency overlap with cetacean call frequencies suggests the potential for call masking and disturbance. Noise mitigation recommendations are made based on site-specific vessel use patterns. Gray whale call detections are used to provide insights into the gray whale migration route and habitat use, which are poorly understood in the study area. The visual and acoustic monitoring conducted in this thesis contributes to cetacean conservation by advancing our understanding of cetacean habitat use and vessel presence in BC.