Terms of Reference

Cumulative Effects Assessment for the West Coast Transient Killer Whale Population

Regional Peer Review - Pacific Region

June 19-20, 2024

Nanaimo, BC

Chairperson: Karen Hunter

Context

Three distinct ecotypes of killer whales (Orcinus orca) inhabit the waters off the Canadian Pacific coast: Offshore, Transient (or Bigg’s), and Resident. The West Coast population of the Transient Killer Whale (TKW) ecotype was listed as Threatened under the Species at Risk Act (SARA) in 2003. Under SARA, the federal government has a commitment to prevent wildlife species from being extirpated or becoming extinct, to provide for the recovery of wildlife species that are extirpated, endangered, or threatened as a result of human activity, and to manage species of special concern to prevent them from becoming endangered or threatened. The Minister of Fisheries and Oceans Canada and the Minister responsible for the Parks Canada Agency are the competent ministers for the recovery of aquatic species at risk.

A cumulative effects assessment (CEA) is required in order to address a high priority recovery measure (RM7) in the draft TKW Action Plan: “Assess cumulative effects of potential anthropogenic impacts on Transient Killer Whales using an appropriate impact assessment framework for aquatic species”^{Footnote 1}. Cumulative effects are the combined, incremental impacts that threats/stressors from multiple human activities can have on individuals, populations, communities, and ecosystems through space and time. The two primary threats to TKW have been identified as:

• environmental contaminants; and
• noise and disturbance (DFO 2007).

Fisheries and Oceans Canada (DFO) Species at Risk Program has requested that Science Branch provide an assessment of the cumulative effects of current and potential anthropogenic impacts on TKW in Canadian Pacific waters. Cumulative effects assessments evaluate the effects of multiple threats by transforming impacts into a single currency or metric, thereby allowing for comparisons among threats and their combined impact on long-term population viability. A cumulative effects assessment was completed to address a similar recovery measure for Northern Resident and Southern Resident Killer Whale populations (DFO 2019; Murray et al. 2019). This study will advance previous methods developed for Resident Killer Whale ecotypes (Murray et al. 2019; DFO 2019; Lacy et al. 2017) to assess cumulative effects to TKW. New acoustic and contaminant research will be considered to improve the treatment of these threats in the model. The relationship between TKW population dynamics and the main prey species (pinnipeds and small cetaceans) will be analysed and included in the model.

The species-focused cumulative effects assessment will be composed of two phases. The first phase is the development of a Pathways of Effects (PoE) conceptual model describing the current understanding of how threats affect the mortality and fecundity of the species. The second phase involves the parameterization of the impacts (e.g., effect size for each threat and its impact on vital rates) and conducting a quantitative population viability analysis (PVA) to assess how cumulative effects affect population dynamics. Identification of critical habitat and evaluation of mitigation measures and management actions are out of scope for this assessment. More information on ongoing initiatives to help recover killer whale populations can be found on the DFO website^{Footnote 2}.

The cumulative effects assessment arising from this Canadian Science Advisory Secretariat (CSAS) Regional Peer Review (RPR) further expands the cumulative effects tools available for DFO, and the advice may be used to inform the SARA program in its efforts toward survival and recovery of this population. This study aims to incorporate best available science into a single assessment that includes the most pressing anthropogenic threats, the interactions between them, and the resulting long-term impacts on the population.

Objectives

The following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below.

• C. Murray, L. Hannah, J. Nelson, T. Doniol-Valcroze, J. Tucker, S. Tucker, S. Vagle, and T. Brown. Cumulative Effects Assessment of the West Coast Transient Killer Whale Population. 2024. CSAP Working Paper 2020SAR03.

The specific objectives of this review are to:

1. Examine the individual components of the TKW cumulative effects assessment, namely: the Pathways of Effects (PoE) conceptual model and Population Viability Analysis (PVA) quantitative model; and assess the biological relevance and the applicability of each component to adequately reflect best available knowledge;

2. Review the resultant cumulative effects assessment for TKW and provide guidance regarding the utility and applicability of the model for future applications; and

3. Identify uncertainties and sensitivities in the data and methods and highlight knowledge gaps for future research.

Expected Publications

• Science Advisory Report
• Research Document

Expected Participation

• Fisheries and Oceans Canada (Science, Species At Risk, Fisheries Protection Program, Oceans, Ecosystems and Oceans Science, and Ecosystems and Fisheries Management)
• Environment and Climate Change Canada
• Georgia Strait Alliance
• International Union for Conservation of Nature
• Maa-nulth First Nations
• Marine Education and Research Society
• Nisga’a Nation (Nisga’a Lisims Government)
• North Coast Cetacean Society
• Ocean Wise
• Orca Lab
• Parks Canada
• Port of Vancouver
• Raincoast Conservation Society
• Simon Fraser University
• Tla’amin Nation
• Transport Canada
• Tsawwassen First Nation
• University of Washington
• World Wildlife Fund Canada

References

• DFO. 2007. Recovery Strategy for the Transient Killer Whale (Orcinus orca) in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Vancouver, vi + 46 pp.

• DFO. 2019. Cumulative Effects Assessment for Northern and Southern Resident Killer Whale (Orcinus orca) Populations in the Northeast Pacific. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2019/030.

• Lacy, R.C., Williams, R., Ashe, E., Balcomb III, K.C., Brent, L.J.N., Clark, C.W., Croft, D.P., Giles, D.A., MacDuffee, M., and P.C. Paquet. 2017. Evaluating anthropogenic threats to endangered killer whales to inform effective recovery plans. Scientific Reports 7: 14119(1): 2045–2322 pp.

• Murray, C.C., Hannah, L.C., Doniol-Valcroze, T., Wright, B., Stredulinsky, E., Locke, A., and R. Lacy. 2019. Cumulative Effects Assessment for Northern and Southern Resident Killer Whale Populations in the Northeast Pacific. DFO Can. Sci. Advis. Sec. Res. Doc. 2019/056. x + 88 p.