Sowerby's beaked whale (Mesoplodon bidens) COSEWIC assessment and status report: chapter 11
Technical Summary
Mesoplodon bidens
Sowerby’s beaked whale – Baleine à bec de Sowerby
Range of Occurrence in Canada:
Atlantic Ocean
Extent and Area Information
Extent of occurrence (EO) (km²)
> 20,000 km²
Specify trend in EO :
Unknown
Are there extreme fluctuations in EO?
Unlikely
Area of occupancy (AO) (km²) :
>20,000 km²
Specify trend in AO :
Unknown
Are there extreme fluctuations in AO?
Unlikely
Number of known or inferred current locations :
Unknown
Specify trend in # :
Unknown
Are there extreme fluctuations in number of locations?
Unlikely
Specify trend in area, extent or quality of habitat :
Likely declining due to increasing seismic operations
Population Information
Generation time (average age of parents in the population) :
Probably 15-30 years (extrapolating from other beaked whales)
Number of mature individuals :
Unknown
Total population trend :
Unknown
% decline over the last/next 10 years or 3 generations :
Unknown
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
Unlikely
Specify trend in number of populations:
Unknown
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
Threats (actual or imminent threats to populations or habitats)
Acute exposure to intense sound (especially from military sonar and seismic operations) has been shown to affect some species of beaked whales, including in lethal ways. The population-level implications for Sowerby’s beaked whale are uncertain but could be significant.
Status of outside population(s)?
USA and elsewhere in temperate North Atlantic: Occur but unknown population size.
Is immigration known or possible?
Unknown
Would immigrants be adapted to survive in Canada?
Likely
Is there sufficient habitat for immigrants in Canada?
Likely
Is rescue from outside populations likely?
Unknown
Quantitative Analysis
Not available
Current Status
- COSEWIC: Special Concern (April 1989/November 2006)
- IUCN: Data Deficient
Status and Reasons for Designation
Status: Special Concern
Alpha-numeric code: Not applicable
Reasons for Designation: This small beaked whale is endemic to the North Atlantic Ocean where it is found mainly in deep, offshore temperate to subarctic waters. Little is known about its biology, fine-scaled distribution, and abundance. It belongs to a family of whales (Ziphiidae) in which acute exposure to intense sounds (especially from military sonar, but also from seismic operations) has led to serious injury and mortality. Seismic operations are currently widespread and military activities involving the use of mid- and low-frequency sonar likely occur at least occasionally in the habitat of this species off Canada’s East Coast. Although there is no direct evidence that such sound sources have affected this species, there is strong evidence for lethal effects on individuals of related species. Thus there is reasonable cause for concern about the potential effects on individuals of this species. The potential population-level impacts of this type of mortality are unknown.
Applicability of Criteria
Criterion A: (Declining Total Population): There is no information on population trends.
Criterion B: (Small Distribution, and Decline or Fluctuation): AO and EO > 20,000 km².
Criterion C: (Small Total Population Size and Decline): Total population size is unknown.
Criterion D: (Very Small Population or Restricted Distribution): Total population size is unknown.
Criterion E: (Quantitative Analysis): No quantitative analysis is available.
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