Grey whale (Eschrichtius robustus) COSEWIC assessment and status report: chapter 13

Technical summary

Eschrichtius robustus
Grey whale
Eastern North Pacific population

Baleine grise

Range of Occurrence in Canada: Coastal waters of British Columbia (BC) and southern Beaufort Sea


Extent and area information

Extent of occurrence (EO) (km 2 ).
(Coastal waters of British Columbia and shallow sections of southern Beaufort Sea between Alaskan border and Cape Bathurst)
250 000 km 2
Specify trend in EO.
Stable
Are there extreme fluctuations in EO?
No, but EO depends on the extent of ice cover in arctic waters (see Perryman et al. 2002)
Area of occupancy (AO) (km 2 ).
(Coastal waters of British Columbia)
150 000 km 2
Specify trend in AO
Stable
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations.
Not applicable
Specify trend in #
Are there extreme fluctuations in number of locations?
Specify trend in area, extent or quality of habitat
Oil and gas exploration off British Columbia could lead to habitat loss and/or deterioration, some breeding lagoons in Mexico continue to be threatened by development


Population information

Generation time (average age of parents in the population).
22 years (Heppell et al. 2000)
Number of mature individuals.
Eastern North Pacific population: 11 000
BC summer resident community: 110
(numbers represent 60% of population estimate)
Total population trend:
Eastern North Pacific population: increasing before 1998, stable or decreasing since 1998
BC summer resident community: stable or increasing
% decline over the last/next 10 years or 3 generations.
Eastern North Pacific population: pre-1998: 2.5% annual increase (Buckland and Breiwick 2002)
1998–2002: 10% annual decrease (calculated from population estimates, see page 15)
post-2002: trend unknown but probably stable or increasing (based on mortality and calf production)
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
No
Specify trend in number of populations.
Are there extreme fluctuations in number of populations?
List populations with number of mature individuals in each:


Threats (actual or imminent threats to populations or habitats)

  • Habitat loss or degradation (e.g., development of breeding lagoons in Mexico, oil and gas exploration along migratory pathways and on feeding grounds in US and Canadian waters,
  • Mortality from entanglement in fishing gear and marine debris
  • Mortality from boat collisions


Rescue effect (immigration from an outside source)

Status of the outside population(s)?
Western North Pacific population: endangered (Weller et al. 2002a)
Is immigration known or possible?
No (LeDuc et al. 2002)
Would immigrants be adapted to survive in Canada?
Not known
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
No


Quantitative Analysis

None


Other Status

COSEWIC: Not at Risk, April 1987.


Status and reasons for designation

Status: Special concern
Alpha-numeric code: Not applicable


Reasons for Designation: Grey whales migrate each year from their winter calving grounds in Mexico to their summer feeding areas in northern Alaska, Russia and Canada. Most of the population passes along the BC coastline, and some individuals repeatedly spend the entire summer feeding in BC (about 80). The population increased by 2.5% per year following the cessation of whaling, and peaked, within the range of pre-exploitation estimates, at about 27 000 animals in 1998. The extent of recovery of the summer resident group is unknown. However, over one-third of the population died from 1998 to 2002 (possibly due to a lack of food in Alaska). Birth rates, survival rates and other indicators suggest that the decline has ceased and that the population is stable or increasing since 2002. The whales are susceptible to human activities in their 4 breeding lagoons in Mexico, as well as to entanglement in fishing gear and collisions with boats throughout their range. Underwater noise associated with proposed oil development in BC could alter migration patterns. The small group of summer-resident whales could also be threatened by subsistence whaling in the USA.


Applicability of criteria

Criterion A: does not apply, although Criteria A4 (Threatened) is close to being met. However, the documented decline appears to be a fluctuation. Vital rates and other indicators suggest the population will not continue to decline.

Criterion B: does not apply. The extent of occurrence is > 20 000 km2.

Criterion C: does not apply.

Criterion D: does not apply. The number of mature individuals is 11 000.

Criterion E: no quantitative analysis has been undertaken.

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