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Terms of Reference

Assessment of Factors in the Mortality of Eastern Beaufort Sea Beluga Whales (Delphinapterus leucas) Live Captured and Tagged in 2019

Regional Peer Review - Ontario and Prairie Region

February 28 - March 3, 2023
Yellowknife, NT

Chairperson: Joclyn Paulic


In July 2018, the first program to tag Eastern Beaufort Sea (EBS) beluga whales (Delphinapterus leucas) since 2005 took place in Kugmallit Bay in the Mackenzie Estuary, Canadian Beaufort Sea. In total, 10 belugas were live-captured and instrumented with back-mounted transmitters following standard methods. The program was highly successful, with tags reporting data between 14–356 days. The following year, an additional 20 EBS belugas were tagged using the same protocols and a virtually identical field crew. However, within two weeks eight whales were confirmed dead based on the mortality function from a secondary pop-up archival tag, along with the discovery of three beachcast carcasses of tagged belugas. An additional eight tags went offline within the same timeframe as those beluga confirmed dead, with no known cause. This represents a mortality rate of 40% percent based on confirmed cases, and potentially as high as 80% if the additional offline tags represent whales that died. This level of mortality is without precedent in any small cetacean live capture program. Tagging belugas with methods used in this program (live capture with dorsal ridge attachment) is currently the only approach that provides movement data (both horizontal and vertical) over long durations (i.e., up to a year). Movement and dive data for Arctic cetaceans is needed to inform stock assessments, integrated marine spatial planning, and to evaluate cumulative effects caused by a changing climate and anthropogenic activities. Currently, the Department has put a freeze on any live capture tagging of belugas and narwhals until an assessment of factors affecting the mortality event is completed and recommendations are provided for future programs. Inuvialuit community members and wildlife co-management partners have also requested more information on potential causes of the mortality event.


To identify and assess likely cause(s) and/or contributing factor(s) in the mortality of tagged EBS beluga using expert elicitation and assigning levels of certainty for each factor. Specifically, to:

  1. Review and evaluate the role of the tagging procedure in the mortality events;
  2. Evaluate the role of underlying health condition(s) in the mortalities using individual and population-level data;
  3. Determine if external factors (e.g., environmental) may have contributed to the mortalities; and,
  4. Discuss lessons learned and identify recommendations for future beluga tagging programs and protocols.

Expected Publications

Expected Participation


Participation to CSAS peer review meetings is by invitation only.

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