Testing whether the Availability of Chinook Salmon is Insufficient to Support a Healthy Southern Resident Killer Whale Population

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The poor body condition of southern resident killer whales in recent years points to them not being able to obtain enough of their preferred prey (Chinook salmon) to meet their daily needs. It is unknown whether this is due to reduced abundance and quality of salmon from overfishing or environmental change, or reduced salmon accessibility by killer whales due to vessel traffic and acoustic disturbance. Our objectives are to 1) test the hypothesis that the availability of Chinook salmon is insufficient to support a healthy population of southern resident killer whales; 2) increase knowledge about the at-sea distribution of this important prey species, and the factors that influence it; 3) determine the time that adult Chinook are available to killer whales and fisheries; and 4) determine the conditions required for killer whales to successfully forage. We will achieve our objectives by a) constructing comparative bioenergetics models to predict daily food requirements of increasing and decreasing pods of southern and northern killer whales, and incorporating environmental variability, fishing pressure, and vessel disturbance to assess impact on nutritional status. We will also track the fine-scale movements of individual killer whales in conjunction with tracking and monitoring the movements of tagged fish using a network of receivers moored in the inside waters of Vancouver Island. The research we are proposing is novel and timely, and complements ongoing research we are doing in partnership with DFO to resolve whether availability of Chinook is sufficient to support southern resident killer whales in British Columbia. Our research will have direct implications for the management of fisheries, the conservation of killer whales, and economies of many of our coastal communities in southern British Columbia. It broadens the base of recovery research in Canada, accelerates the development of marine mammal scientists, and ultimately increases the scientific information available to support government decision-making and conservation efforts for a priority whale species.