Sea otter (Enhydra lutris) COSEWIC assessment and status report 2007L chapter 13
Range of Occurrence in Canada: Pacific Ocean
Extent and Area Information
Coastal waters of west coast Vancouver Island and central British Columbia coast where sea otter occupation has been confirmed from dedicated surveys and from ATK . It does not include sightings of single animals outside this continuously occupied range. Area is calculated from shore to the 50 m depth contour; deep inlets are cut off.
same as EO
age at first birth = 3, longevity = 15 to 20, gen.time = 3 + .33(15-3) to 3 + .33(20-3)
Data to produce a life table do not exist for British Columbia. The proportion of adults is assumed to be 50% of the total population based on estimates of age at first reproduction of other sea otter populations.
Population data from Watson et al. 1997 and Nichol et al. 2005 indicate that the population has been increasing.
18.6% yr -1 (1977-1995)
15.6% yr -1 (1977-2004)
19.1% yr -1 (1977-1995)
8.0% yr -1 (1995-2004)
Central B.C. coast
12.4% yr -1 (1990-2004)
Threats (actual or imminent threats to populations or habitats)
Environmental contamination, especially oil spills, entanglement in fishing gear and collision with vessels, illegal killing.
Rescue Effect (immigration from an outside source)
State Special Species Policy – Washington – Endangered
[provide details on calculation, source(s) of data, models, etc]
COSEWIC: Threatened (2000)
Special Concern (2007)
Status and Reasons for Designation
Reasons for Designation: The species had been extirpated in British Columbia by the fur trade by the early 1900s, and was re-introduced from 1969-72. It has since repopulated 25-33% of its historic range in British Columbia, but is not yet clearly secure. Numbers are small (< 3500) and require careful monitoring. Their susceptibility to oil and the proximity to major oil tanker routes make them particularly vulnerable to oil spills.
Applicability of Criteria
Criterion A (Declining Total Population):
The population has increased at rates of 8 – 19% per year since censuses were initiated in 1977. The rate of increase has slowed in recent years.
Criterion B (Small Distribution, and Decline or Fluctuation):
Extent of occurrence is < 20 000 km2, but the population is not declining or fluctuating.
Criterion C (Small Total Population Size and Decline):
Total population is ~3200 animals of which half are assumed to be mature individuals (~1600). The population is small, but there is no decline or fluctuation in numbers.
Criterion D (Very Small Population or Restricted Distribution):
There are > 1000 mature individuals.
Criterion E (Quantitative Analysis):
None have been undertaken.
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