Threat assessment for the critically endangered North Atlantic Right Whale (Eubalaena glacialis)

Abstract

The North Atlantic right whale (NARW, Eubalaena glacialis) is a critically endangered species with a population of less than 400 individuals. Between 2010 and 2020 the population experienced an estimated decline of 126 individuals. This decline has been exacerbated by low reproductive rates, declining health, and high rates of anthropogenic related, sublethal injuries. The NARW faces a plethora of threats and this assessment evaluated some of the Historical, Current, and Anticipatory threats that occur not only in Canadian waters, but throughout NARW core habitat areas. Threats assessed included fishing-gear entanglements, vessel strikes, vessel presence disturbance, and various sources of noise pollution, including marine traffic, seismic surveys, active acoustic technologies operation, and mid-frequency military active sonar operation, as well as other threats such as persistent organic pollutants pollution, plastics and marine debris pollution, petroleum spills, coastal and marine offshore development, drilling operations, wind energy production, climate change, scientific activities, whaling, and food supply reduction through direct harvesting of prey. The Likelihood of Occurrence was assessed as Known (>90% chance of occurring over the next 100 years) for all but two anticipatory threats (whaling, and food supply reduction through direct harvesting of prey). Due to the uncertainty in the estimation of the Population Level of Impact, the majority of threats had a Threat Risk (the product of Population Level of Impact and Likelihood of Occurrence) assessed as Unknown, although it should not be assumed that such threats do not have population level impacts. Fishing-gear entanglements had an Extreme ranking for the Population Level of Impact, while vessel strikes, petroleum spills, and climate change were ranked as High. To provide further insights in the impact of these threats, especially for a species that has an estimated Potential Biological Removal of less than one, the Individual Level of Impact was also defined and evaluated. The Individual Level of Impact incorporated information not only on mortalities, but also on sublethal effects (including injuries, disturbances, effects on reproduction, and increased stress) and provided further insights on Threat Risk. Many of the threats intersect with one another, however, the cumulative effects of the threats were not assessed. It is essential for the survival and recovery of the NARW not to focus solely on mortalities and population level impacts. Investigating individual impacts on health and reproductive rates will provide further information which can be used to inform conservation initiatives aimed at reducing threats to the survival and recovery of the NARW.