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Review of the Effectiveness of Recovery Measures for Southern Resident Killer Whales

Context/Background

Review of the Effectiveness of Recovery Measures for Southern Resident Killer Whales

Review of the Effectiveness of Recovery Measures for Southern Resident Killer Whales (PDF, 1.36 MB)

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1.0 Context/Background

In November 2016, Canada’s Oceans Protection Plan (OPP) was announced, which outlined several new initiatives aimed at addressing threats to marine mammals in Canadian waters, including the key threats of contaminants, prey availability, and underwater noise. As part of OPP, Fisheries and Oceans Canada (DFO) was tasked with launching a science-based review of the effectiveness of the current management and recovery actions for three at-risk whale species in Canada: the Southern Resident Killer Whale (SRKW), the North Atlantic Right Whale (NARW), and the St. Lawrence Estuary Beluga (SLE Beluga). This review seeks to evaluate the effectiveness of the recovery actions currently underway in order to identify how recovery objectives can be better achieved, and provide guidance on the relative priority of actions required to promote recovery. DFO adopted a phased approach for this review, and this document represents the first phase in that process and is focused on the SRKW population from a scientific perspective.

Two distinct populations of Resident Killer Whales occupy the waters off the west coast of British Columbia. These populations are referred to as the Northern Residents and Southern Residents, and although the ranges of the two populations overlap, they are acoustically, genetically and culturally distinct from each other. This document presents an assessment of the effectiveness of current management and recovery actions under way for the SRKW from a scientific perspective. The SRKW population was designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2001 and was subsequently listed as Endangered, under Canada's Species at Risk Act (SARA) in 2003. COSEWIC's designation was based on the following reasons, which remain valid today:

"The population is small and declining, and the decline is expected to continue. Southern residents are limited by the availability of their principal prey, Chinook salmon. There are forecasts of continued low abundance of Chinook salmon. Southern residents are also threatened by increasing physical and acoustical disturbance, oil spills and contaminants" (COSEWIC 2008).

In 2006, SRKWs were also listed as Endangered under the US Endangered Species Act.

Between 1964 and 1973, the SRKW population was impacted by the loss of at least 46 animals from the effects of the live capture fishery. In 1974, a stock assessment program was initiated, and the first population census identified 71 SRKWs. Over the subsequent decades, the population has been assessed annually, and has fluctuated from the low of 71 animals in 1974 to a high of 96 in 1996. As of late 2016, there are 78 animals. Given the population size, the number of reproductively contributing animals in the population is small. Furthermore, SRKW females are less productive than their Northern Resident Killer Whale (NRKW) counterparts (Ward et al. 2009) and survival of neonates is also lower. The SRKW population exhibits lower survival overall when compared to NRKWs. Collectively, the small population size and low number of individuals contributing to reproduction (termed the effective population) heighten the impact of any mortality or loss of reproductive potential to the population's survival relative to their northern counterparts.

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