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Research Document 2022/037

Southern Resident Killer Whale (Orcinus orca) summer distribution and habitat use in the southern Salish Sea and the Swiftsure Bank area (2009 to 2020)

By Thornton, S.J., Toews, S., Stredulinsky, E., Gavrilchuk, K., Konrad, C., Burnham, R., Noren, D.P., Holt, M.M., and Vagle, S.


The Southern Resident Killer Whale (SRKW; Orcinus orca) population in Canadian Pacific waters is listed as Endangered under the Species at Risk Act. Efforts in support of recovery are underway from numerous government sectors, stakeholders, industry and others. Critical habitat has been identified for this population and includes the waters on the continental shelf off southwestern Vancouver Island and eastward to portions of the inner waters of the Salish Sea. As the spatial extent of critical habitat is large, there is a need to focus mitigation efforts on areas that have the greatest potential to provide benefits to the population. To support requests for advice on spatial and temporal boundaries identifying areas of high relative SRKW occurrence, a novel approach was undertaken to facilitate collation of disparate datasets and to address preferential sampling bias in sightings data. The results presented here indicate that from May to October, the highest SRKW frequency of occurrence is found in the waters in the vicinity of Swiftsure Bank, the eastern portion of Haro Strait, sections of Swanson Channel and Boundary Pass, and near the Fraser River. Analysis of behavioural data provides further information on habitat use and identifies key foraging areas at Swiftsure Bank and Haro Strait. Evaluation of acoustic detections and encounter durations from recorders deployed in SRKW critical habitat lend further support to strengthen the interpretation of sightings data and provide further information on fine scale habitat use within the population’s critical habitat.

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