Patterns of seasonal occurrence of sympatric killer whale lineages in waters off Southern Vancouver Island and Washington state, as determined by passive acoustic monitoring
Supervisory Committee Dr. N. Ross Chapman (School of Earth and Ocean Sciences) Supervisor Dr. Richard K. Dewey (School of Earth and Ocean Sciences) Departmental Member Dr. S. Kim Juniper (School of Earth and Ocean Sciences) Departmental Member Dr. John K. B. Ford (Pacific Biological Station) Additional Member Killer whales inhabiting coastal waters of the northeastern Pacific are listed under the Canadian Species at Risk Act, which requires the identification of critical habitats for the recovery of their populations. Little is known about their distribution during the winter and what areas are important for their survival during these months. Passive acoustic monitoring is a valuable complementary method to traditional visual and photographic surveys although it has seldom been used to study killer whales and there are limitations in practice. There is a need to develop tools and protocols to maximize the efficiency of such studies. In this thesis, long term acoustic data collected with autonomous recorders were analyzed 1) to assess the performance of two types of analysis (Manual and Long Term Spectral Averages) for detecting and identifying killer whale calls and to compare the effects of using two different duty cycles (1/3 and 2/3) and 2) to investigate the seasonal occurrence of different killer whale populations at two sites off the west coasts of Vancouver Island and Washington: Swiftsure Bank and Cape Elizabeth. Both the use of Long Term Spectral Averages and a lower duty cycle resulted in a decrease in call detection and resolution of call identification, leading to underestimations of the amount of time the whales spent at the site. A compromise between a lower resolution data processing method