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Recovery Strategy for the Transient Killer Whale (Orcinus orca) in Canada


2. Recovery

2.1 Recovery Feasibility

Transient killer whale populations are not expected to achieve high abundances due to their ecological position as upper trophic-level predators and their apparent propensity to live in relatively small populations.  It is presumed that population abundance is limited by prey availability, and whether the current population is below or at carrying capacity is unknown.  Regardless, the threat of decline due to the strikingly high contaminant burden that this population carries as a result of bioaccumulation through its prey, along with other potentially significant threats such as disturbance and prey reduction, warrants the protection of Species at Risk Act prohibitions and the implementation of recovery actions that will address threats, so that transient killer whales do not decline to an Endangered status.  (See section 1.5.2 for the classification of threats and associated risk).  As technologies and methodologies currently exist to reduce many of the threats facing killer whales, their prey and their habitat, recovery is considered feasible.    

Contaminants are considered a high priority threat that must be addressed, and sources of these chemicals are widespread and diffuse.  Accordingly, cooperation among federal, provincial and municipal governments, industries that produce or use these chemicals, and action at a citizen level, will be necessary to mitigate the effects of this threat.  Effective implementation of initiatives such as Environment Canada’s Georgia Basin Action Plan (EC-GBAP 2005), Environment Canada’s regulatory review of these chemicals, and non-governmental programs such as the Green Boater Program and Pesticide Free Lawns, will complement the objectives in this recovery strategy to improve the quality of killer whale prey and their habitat, and reduce disturbance to important life processes.  The decline of PCBs, DDT, dioxins and furans in the local marine environment since their source control and regulation demonstrates that actions taken can have tangible results and should serve as a model for the management of persistent, bioaccumulative and toxic (PBTs) chemicals, such as the largely unregulated PBDEs.

As prohibitions on the killing of pinnipeds since the early 1970s have resulted in pinniped populations approaching or at historic levels of abundance, there appears to be no immediate threat of prey limitation.  However, further research on the dietary needs of the transient population is required.  

Finally, measures to address the threat of disturbance have resulted in a reduction in disturbance from some priority activities.  The successful implementation of monitoring programs for boaters viewing and operating vessels around all marine mammals, including transient killer whales, indicate a greater awareness and compliance to appropriate boating practices (e.g., ‘Be Whale Wise’ boating guidelines developed by DFO and the US National Oceanic and Atmospheric Administration).  Ecotourism operators in British Columbia have shown leadership and initiative in developing codes of practices, such as the ‘Best Practices Guidelines’ developed by the industry-based Whale Watch Operators Association- Northwest (WWOANW 2006), which have also evolved to consider new information regarding activities that cause disturbance.  Protocols for the mitigation of acute noise from both military active sonar and seismic have similarly reduced the threat of disturbance or injury from these activities (see Section 1.6.2).

2.2  Recovery Goal

To attain long-term viability of the West Coast transient killer whale population by providing the conditions necessary to preserve the population’s reproductive potential, genetic variation, and cultural continuity

2.3 Population Objectives

This recovery goal reflects the complex social and behavioural dynamics of transient killer whales and the key threats that may lead to their decline.  In the absence of historical data, it does not identify a numerical target for a “viable” population because the current understanding of killer whale population demographics is inadequate for setting a meaningful value at this time.  However, because maintaining the demographic conditions that will preserve the population’s reproductive potential, genetic variation, and cultural continuity is fundamental to the population’s continued existence, population objectives, in the form of demographic indicators, have been expressed herein that will serve as interim measures of recovery success.

There are three population objectives for the five-year time span of this recovery strategy: 

  • P1 The population size, averaged over the next five years, will remain at or above the current level.

  • P2 The number of breeding females in the population, averaged over the next five years, will remain at levels that will provide a neutral or positive growth rate.

  • P3 Studies will be undertaken to determine numerical and demographic population objectives that represent long-term viability for this population. 

2.4 Distribution Objectives

Transient killer whales currently range widely throughout British Columbia, and into southeastern Alaska and Washington state waters.  This range likely reflects the whales’ hunting strategies and the wide distribution of their prey.  At the same time, little is understood about how transient killer whales associate and how groups range and utilize the known habitat. The following distribution objectives are directed at understanding these relationships and ensuring that the population, as a whole, has access to adequate quantities of their known prey species throughout their range. 

There are three distribution objectives for the five-year time span of this recovery strategy: 

  • D1 Transient killer whales will continue to utilize their known range.

  • D2 Prey will be available, in quantities adequate to support recovery, throughout the currently known range of transient killer whales.

  • D3 Studies will be undertaken to determine how the range is utilized at a population and sub-population level. 

2.5 Recovery Objectives

To achieve protection (recovery) of this population, studies to understand conservation threats and the development of measures to address the threats are necessary. Given our current knowledge, the primary anthropogenic threats to the long-term survival of transient killer whales appear to be environmental contaminants and disturbance.  However, while some of the key prey species of pinniped are currently at historic high levels, the potential for these populations to decline because of human activities dictates the need for objectives to ensure prey remains available at sufficient quantities and of adequate quality so as not to limit transient killer whale population maintenance and/or increases. 

Recovery objectives for the next five years of this recovery strategy, which directly address these threats and contribute to achieving the overarching long term recovery goal and the population and distribution objectives, are outlined below.  The first four objectives provide direction for the strategies and approaches that can be used to mitigate and/or eliminate each of the threats facing transient killer whales.  The remaining four objectives focus on obtaining information needed to develop a more comprehensive understanding of these threats, which will allow for the refinement of mitigation measures. 

  • R1 Minimize the exposure to transient killer whales to legacy and emergent pollutants.

  • R2 Minimize the risk of prey population reductions from anthropogenic activities, until precise prey needs can be determined.

  • R3 Current measures to protect transient killer whales from vessel disturbance will be maintained or modified, if determined necessary from further studies.

  • R4 Minimize the exposure of transient killer whales to acute or chronic sound levels in excess of those considered to cause behavioural or physical harm in cetaceans.

  • R5 The quantity, quality and distribution of transient killer whale prey necessary to sustain or increase the current population level will be determined.

  • R6 A greater understanding of the impacts of contaminants and other biological and non-biological pollutants on transient killer whales will be developed.

  • R7 The effects of vessel disturbance on transient killer whales will be evaluated.

  • R8  A more comprehensive understanding of the impacts of chronic and acute noise on transient killer whales will be developed.

2.6 Approaches Recommended to Meet Recovery Objectives

Approaches recommended to achieve the population, distribution and recovery objectives outlined in Section 2.3, 2.4 and 2.5 are detailed in Table 2 and are meant to serve as guidance to future Action Planning, as required by SARA and to recovery activities that will be undertaken by government and non-government organizations. Although the objectives are focused on a five-year term, the many approaches outlined below will likely extend past the term of this recovery strategy or be ongoing requirements.  

In addition to the lead role DFO has for this population’s recovery, there are several government agencies who have a key role in supporting transient killer whale protection and recovery including: Parks Canada, Environment Canada,  the Department of National Defence, Natural Resource Canada and the Province of British Columbia. 

While governments and agencies have legislative and program responsibilities to support transient recovery, the role of non-government organizations and the public in general cannot be underestimated with respect to effecting transient recovery.  Stewardship, education and outreach need to be considered in each of the following specific approaches for recovery.

2.6.1 Recovery planning

Table 2. Recovery Planning Table
ObjectiveThreats addressedBroad strategy to address threatRecommended approaches to meet recovery objectives
P1 & P2: Population size and demographic monitoringn/aPopulation censusDirected surveys
Collaborations with other transient researchers
Formal and informal sightings networks including opportunistic photo-identification
Analytical modellingNumerical and demographic population modelling
P3: Setting demographic and numerical population objectivesn/aAnalytical modellingNumerical and demographic population modelling
D1 & D3: Monitoring of range utilizationn/aPopulation censusDirected surveys
Collaborations with other transient researchers
Formal and informal sightings networks including opportunistic photo-identification
D2: Monitoring of prey distributionn/aPopulation monitoringPinniped surveys
Formal and informal sightings networks for small cetaceans
R1: Reducing contaminants in Transient Killer Whales (TKW) and their preyContaminationRegulations & ProhibitionsMaintain and enforce existing prohibition on regulated PBTs and other non-PBT chemicals
Evaluate the need for and efficacy of prohibitions on use of unregulated PBDEs and other non-PBTs that affect TKW or their prey and implement mitigation measures as necessary
International cooperation and collaboration to reduce PBTs used outside Canada that contribute to Canadian contaminant levels
Stewardship & EducationGovernment and non-government education and stewardship programs for industrial and private use of PBT and non-PBT compounds including currently used pesticides
Contaminant MonitoringDedicated sampling program for transient killer whales
Dedicated sampling program for harbour seals
Benchmark studies for other important prey species (other pinnipeds and cetaceans)
Sediment sampling and monitoring (provides link to model food web bioaccumulation & link to sediment quality guidelines)
Necropsy stranded TKW to evaluate possible exposure to contaminants,  biological pollutants & pathogens
R2: Protecting Prey PopulationsPrey limitationPinniped harvest protectionMaintain current harvest restrictions and ensure research, nuisance seal or other authorized removals do not cause pinniped population level reductions
Small Cetacean protectionMaintain harvest restrictions and develop and/or maintain programs to protect small cetaceans from anthropomorphic threats
R3: Protecting TKW from vessel disturbanceDisturbanceRegulationsImplement the proposed Marine Mammal Regulation amendments of the Fisheries Act
Stewardship & EducationGovernment and non-government education and stewardship programs for stewardship and education programs aimed at reducing vessel disturbance
GuidelinesAmend as necessary and/or develop species or area specific guidelines for viewing of transient killer whales
Enforcement & MonitoringContinue and modify, as necessary, enforcement and monitoring programs directed to compliancy with guidelines and regulations
Evaluate the efficacy of enforcement and education programs, and develop as necessary new approaches and protocols for TKW
R4: Protecting TKW from harmful acute and chronic sound exposureDisturbance & harmSeismic survey managementReview, develop and implement mitigation measures for all seismic surveys conducted throughout British Columbia TKW range to prevent disturbance or injury
Sonar managementContinue development and implementation of adequate National Defence sonar protocols to minimize risk of exposure of transients to intense sound sources
R5: Determining prey needsPrey limitationStudies on foragingOpportunistic prey sampling during dedicated population census surveys
Directed surveys to determine diet of transients in offshore waters
Population abundance surveys of cetacean prey species
Opportunistic observations through formal and informal sightings networks
R6: Understanding the effects of contaminants and biological pollutants on TKWToxic ContaminationData collection, analysis & modellingDevelop methods to measure the contaminant effects on health of TKW using biopsy
Demographic data exploration to evaluate possible population level impacts
Studies on surrogate speciesControlled stuides on surrogate species (laboratory animals or other more abundant species auch as harbour seals) to predict effects of contaminants on TKW
Biological Pollutants & PathogensAnalysis of existing and new necropsy dataNecrospy, sample collection and analysis of samples
R7: Understanding vessel disturbance effectsDisturbanceBehavioural studiesDedicated studies of foraging behaviour and predation rates in the presence of vessels
R8: Understanding the effects of acute and chronic sound exposureDisturbance & harmBehavioural studiesDetermine effect of high levels of chronic and acute industrial underwater noise on TKW behaviour and foraging success
Data synthesisCompile existing data to evaluate the impact of chronic and acute sound exposure

2.7  Performance Measures

The performance measures that will be used to determine whether the objectives established within this recovery strategy are effective are explicitly stated within the objectives themselves. The evaluation of the performance of this recovery strategy will thus be addressed through the achievement of each objective.  Given our limited understanding of transient killer whale population dynamics, the role of prey limitation, the mechanisms and effects of anthropogenic threats and potential for synergistic effects between threats, completing the studies identified in this recovery strategy is a crucial first step towards achieving the long term goal of population viability.  However, it is uncertain whether these information gaps can be filled within a five-year time period and this will be considered in the overall evaluation at the end of this timeline.

2.8 Critical Habitat

“Critical habitat” is defined under SARA as “the habitat that is necessary for the survival or recovery of a listed wildlife species that is identified as the species’ critical habitat in the recovery strategy or in an action plan for the species” (SARA s.2 (1)).  Under SARA, defining critical habitat for transient killer whales to the extent possible is a legal requirement (SARA s.41 (1) (c)).  However, there are significant gaps in our knowledge of the habitat requirements of transient killer whales. 

Transients do not appear to be limited by specific physical features of the environment, other than features that may help them to successfully capture their prey.  They generally range widely over the coast, and although transients may be seen year-round, they rarely remain in any one area for extended periods, likely because their hunting tactics rely on being able to surprise their prey.  Once prey becomes alerted to the presence of transient killer whales in an area, they engage in anti-predator behaviours and become more difficult to capture.  Ambient noise is potentially an important factor influencing foraging success of transients, as they likely detect prey by passive listening (Barrett-Lennard et al. 1996, Ford and Ellis 1999).  Transients could potentially be displaced from foraging habitat if chronic anthropogenic noise interferes with prey detection.  Transients often return repeatedly to particular areas to forage (e.g. seal and sea lion haul-outs), but our understanding of which of these areas are important to transients on a population level is still very limited.  Consequently, it is necessary to develop a Schedule of Studies to better understand and identify critical habitat.  This is included in Section 2.8.1, Schedule of Studies to Identify Critical Habitat.

2.8.1 Schedule of Studies to Identify Critical Habitat

Table 3. Scheduleof Studies for the Identification of Critical Habitat
Description of ActivityOutcome/RationaleTimeline
Spatial analysis of existing sighting dataTo better understand habitat utilizationWithin one year of recovery strategy of acceptance
Spatial analysis of existing data with respect to the distribution of the prey of transient killer whalesTo better understand habitat utilization and whether transient distribution is correlated to prey abundanceWithin next five years
Spatial analysis of transient kill locations with respect to ambient noise environmentTo determine whether transient hunting success is influenced by anthropogenic noiseWithin next five years
Year-round surveys to determine range and seasonal movements of transientsTo better identify areas of occupancyWithin next five years
Year-round surveys to determine the spatial and temporal distribution and abundance of small cetaceansTo better understand habitat utilization and whether transient distribution is correlated to prey abundanceWithin next five years
Formal and informal sightings network for TKW and small cetaceansAcquire better information on the distribution of transient prey and how it may influence transient distributionWithin next five years

2.9 Effects on Other Species

The collateral effects of protecting the habitat for transient killer whales through addressing contaminants and other sources of pollution are likely to be widespread, and will be beneficial to human health as well as to a wide variety of organisms including transient prey. However, if transient killer whale populations increase, a reduction from the current high levels of abundance of pinniped populations might be anticipated.  However, it would not be expected that these populations would be in jeopardy.  Not enough is known about the population status of cetacean prey species to predict an effect.  The strategies to protect transient killer whales from disturbance are complimentary to those recommended for resident killer whales and will have a positive effect on marine mammals in general.  

2.10 Recommended Approach for Recovery Implementation

A single species, single population approach is recommended for recovery of transient killer whales that encompasses a variety of strategies that focus on the threats to killer whales, their prey and their habitat.  However, because the strategies to address threats and some of the research needs are similar to those for resident killer whales, in practicality, it is likely that some activities will be conducted in a combined or complementary fashion.

2.11 Statement on when Action Plans will be Completed

Within two years of posting the final version of this recovery strategy, one or more action plans will be developed.  The plan(s) will include descriptions of programs, plus a timeline of programs with estimated budgets and will encompass a timeframe of at least five years.  The action plan(s) will complement the action plan(s) that are to be developed for resident killer whales, where appropriate, and may be coordinated for certain aspects if logistically feasible.  In the interim, many of the strategies in this document can be acted on and therefore, recovery implementation will be an ongoing activity that can occur in the absence of any formal action plan.