Science Advisory Report  2011/031

Recovery Potential Assessment for Northern Bottlenose Whales (Hyperoodon ampullatus) in Canada

Summary

• COSEWIC recognises two populations of northern bottlenose whales in Canada: the Scotian Shelf population and the Davis Strait population.
• The most recent published population estimate (average population estimate for the 1988 to 2003 period) for the Scotian Shelf is 163 individuals (95% confidence interval 119–214). There was no trend in abundance during that period.
• The Scotian Shelf population ranges from Georges Bank to the Eastern Scotian Shelf. Sightings are highly aggregated in the Gully, Haldimand Canyon and Shortland Canyon. There is no evidence that range has decreased.
• The recovery target for the Scotian Shelf population is to maintain a stable or increasing population and to maintain, at a minimum, current distribution.
• There is no estimate of abundance for the Davis Strait population. Recent vessel-based and aerial survey efforts yielded few sightings. It is likely that this long-lived species is still recovering from whaling.
• The Davis Strait 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.
• In light of the paucity of information on a secure population size, the proposed recovery target for the Davis Strait population is to achieve an increasing population size and to maintain, at a minimum, current distribution. Given that 818 whales were removed by whalers between 1969 and 1971, a minimum target would be a population size greater than this. 
• The whales’ primary prey item is deepwater squid from the genus Gonatus.
• 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 prey (Gonatus squid).
• Zone 1 of the Gully Marine Protected Area and areas with water depths of more than 500 metres in Haldimand Canyon and Shortland Canyon 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.
• Threats include entanglement/bycatch in fishing gear and ocean noise (particularly from oil and gas exploration and extraction).
• No full commercial seismic exploration programs are occurring or planned in either centre of distribution. Haldimand and Shortland canyons are considered areas of potential for oil and gas extraction. DFO has a Statement of Canadian Practice on the Mitigation of Seismic Noise in the Marine Environment, although the mitigation measures therein may be insufficient for northern bottlenose whales. The Canadian Navy has developed marine mammal mitigation procedures to follow when conducting Exercises-Operations that involve the use of Underwater Sound Generating Systems.
• There have been nine reported entanglements of northern bottlenose whales in the past 30 years. Two of the fisheries implicated are no longer prosecuted. This is the only documented source of human-induced harm or mortality in Canada.  Potential mitigation measures include education of members of fishing industry on safe handling and release techniques and on the risks associated with feeding whales. Area closures could be used should areas of high entanglement risk be identified.
• The stock origin of whales off Newfoundland is not known.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat meeting of the National Marine Mammal Peer Review Committee (NMMPRC) of November 22-26. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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