Research Document - 2013/038
Biology, Status, and Recovery Potential of Northern Bottlenose Whales (Hyperoodon ampullatus)
By L.E. Harris, W.E. Gross, and P.E. Emery
Abstract
Northern Bottlenose Whales in Canada range from Georges Bank to southern Baffin Bay. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) recognises two populations of Northern Bottlenose Whales in Canada: the Scotian Shelf population and the Davis Strait-Baffin Bay-Labrador Sea population. The Davis Strait population was designated Not at Risk by COSEWIC in 1993. The Scotian Shelf population was assessed as Endangered in 2002 and added to Schedule 1 of the Species at Risk Act (SARA) in 2006. In 2011, COSEWIC reassessed both populations and designated the Scotian Shelf population as Endangered and the Davis Strait population as Special Concern. In anticipation of this assessment, Fisheries and Oceans Canada conducted a Recovery Potential Assessment (RPA) in November 2010. This RPA will inform the SARA listing decision by the federal Governor in Council, socio-economic analyses, and consultations with the public. The RPA will also inform the recovery strategy(ies) of Northern Bottlenose Whale populations listed as Threatened or Endangered under the SARA.
The most recent published population estimate (average population estimate for the 1988 to 2003 period) for the Scotian Shelf is 163 individuals. There was no trend in abundance during that period. This population ranges from Georges Bank to the eastern Scotian Shelf; however, the majority of sightings are highly aggregated in the Gully, Haldimand Canyon, and Shortland Canyon. There is no evidence that range has decreased. There is no estimate of abundance for the Davis Strait population. Vessel-based and aerial survey efforts yielded few sightings between 2003 and 2007. It is likely that this long-lived species is still recovering from whaling. This population ranges from the Labrador Sea to southern Baffin Bay. Sightings are aggregated in the deep waters of the Davis Strait along the shelf edge, from the mouth of Hudson Strait to the mouth of Cumberland Sound.
The whales’ primary prey item is deepwater squid from the genus Gonatus. Northern Bottlenose Whale habitat is characterised by waters of more than 500 metres in bottom depth, particularly around steep-sided features, which provide access to sufficient accumulations of Gonatus squid.
Zone 1 of the Gully Marine Protected Area and areas with water depths greater than 500 metres in Haldimand and Shortland canyons have been declared Critical Habitat for the Scotian Shelf population. Northern Bottlenose Whales do not have any known dwelling-place similar to a den or nest during any part of their life cycle; hence, the concept of “residence” does not apply.
The main human-induced threats are anthropogenic ocean noise (particularly from oil and gas exploration and extraction) and entanglement/bycatch in fishing gear. The latter is the only documented source of human-induced harm or mortality in Canada. Potential mitigation measures include education of members of the fishing industry on safe handling and release techniques and on the risks to nearby feeding whales. Area closures could be used should areas of high entanglement risk be identified.
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