Évaluation du potentiel de rétablissement de la baleine noire de l'Atlantique Nord (Eubalaena glacialis)

Abstract

The North Atlantic right whale (NARW; Eubalaena glacialis) was assessed as endangered by the Committee on the Status of Endangered Wildlife in Canada in 2003; a status which was re-confirmed in 2013. In 2005, the NARW was listed as Endangered on Schedule 1 of the Species at Risk Act. Given the substantial advancements in our knowledge of NARWs in Canadian waters since the last Recovery Potential Assessment in 2007, and the significant changes observed in the distribution and habitat use of NARWs in Canada since 2010, an updated assessment was requested. The main objective of this Recovery Potential Assessment was to provide up-to-date information, including the associated uncertainties, on the following elements: recent abundance trajectory; current distribution; contemporary life-history parameters; identification of important habitat; threats and limiting factors to the survival and recovery of NARWs; identification of activities likely to destroy important habitat; recovery targets for the abundance and distribution of the NARW; and, to evaluate the maximum human-induced mortality that the species can sustain without jeopardizing its survival or recovery. The NARW represents a single population with no distinguishable units and a population estimate of 372 (credible interval: 360 – 383 individuals) in 2023. The sharp decrease in population size observed from 2015 – 2020 appears to have slowed, though the trajectory of the abundance remains uncertain. Summary information for 23 threats to NARWs were presented and predation, prey availability, pathogens, diseases, genetics and inbreeding were considered limiting factors for the species. Identified important habitat comprises: the southern and northwestern Gulf of St. Lawrence; including the Jacques-Cartier Strait and entrance to Chaleur Bay; the Scotian Shelf, especially Emerald and Roseway Basins; the Bay of Fundy; and the Canadian portions of Georges Bank and the Gulf of Maine. The important habitat also includes corridors for migratory movements and habitat connectivity, namely, the Laurentian Channel, Honguedo Strait, the western portion of the Jacques Cartier Strait, Cabot Strait, and eastern Scotian Shelf. Distributional recovery targets for NARWs included maintaining the historical and contemporary distribution of NARWs in Canadian waters with unimpeded access to migratory corridors and aggregation areas, and maintaining unrestricted movement to identified potential feeding areas and the migratory corridors that connect these potential feeding areas to identified important habitat. A long-term recovery target could be to reach more than 1,000 mature individuals. Proximate recovery targets could be to achieve: sustained positive growth rate for one generation (35 year) or a doubling of the population in one generation. A range wide population viability analysis allowed for the presentation of relative risk reduction scenarios that would achieve the recovery targets based on decreases in fishing-gear entanglements, vessel strikes, and/or prey availability.