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COSEWIC assessment and status report on the Atlantic Salmon (Lake Ontario population) in Canada

Technical Summary


Salmo salar
Common name: Atlantic salmon       Saumon atlantique population de lac Ontario
Population name: Lake Ontario population
Range of Occurrence in Canada: Ontario: historically throughout Lake Ontario basin

Extent and Area information

·        extent of occurrence (EO)(km²) (freshwater phase)       Formerly Lake Ontario basin, now zero km²
·        specify trend (decline, stable, increasing, unknown)       Now extirpated
·        are there extreme fluctuations in EO (> 1 order of magnitude)?       N/A
·        area of occupancy (AO) (km²) (freshwater phase)       Now zero km²
·        specify trend (decline, stable, increasing, unknown)       N/A
·        are there extreme fluctuations in AO (> 1 order magnitude)?       N/A
·        number of extant locations       None
·        specify trend in # locations (decline, stable, increasing, unknown)       N/A
·        are there extreme fluctuations in # locations (>1 order of magnitude)?       N/A
·        habitat trend:  specify declining, stable, increasing or unknown trend in area, extent or quality of habitat       Improving in rivers; possibly declining in lake

Population information

·        generation time (average age of parents in the population) (indicate years, months, days, etc.)       Unknown (3-5 years in eastern Canada)
·        number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)       None
·        total population trend:  specify declining, stable, increasing or unknown trend in number of mature individuals       N/A
·        if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)      N/A
·        are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?      N/A
·        is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)?      N/A
·        list each population and the number of mature individuals in each      N/A
·        specify trend in number of populations (decline, stable, increasing, unknown)      N/A
·        are there extreme fluctuations in number of populations (>1 order of magnitude)?      N/A

Threats (actual or imminent threats to populations or habitats)

Causes of extirpation include deterioration in spawning habitat due to timbering, agriculture, and mills and dams across rivers that prevented access to spawning grounds, in addition to extensive commercial and food fisheries.

Rescue Effect (immigration from an outside source)      Unknown

·        does species exist elsewhere (in Canada or outside)?      Atlantic salmon are found in eastern Canada; however, these populations are likely to be genetically distinct from the Lake Ontario Atlantic salmon DU.  Stocking of North American strains into Lake Ontario has not produced a self-sustaining population.
·        status of the outside population(s)?      Generally declining or stable at reduced numbers; Inner Bay of Fundy Atlantic salmon designated Endangered (COSEWIC 2001; SARA 2003).  Most US populations designated Endangered (ESA 2000).
·        is immigration known or possible?      No
·        would immigrants be adapted to survive here?      Unknown
·        is there sufficient habitat for immigrants here?      Unknown

Quantitative Analysis

Status and Reasons for Designation

Status :  Extirpated
Alpha-numeric code :  Not Applicable
Reasons for Designation: Once a prolific species throughout the Lake Ontario watershed, there has been no record of a wild Atlantic salmon since 1898.  The Lake Ontario Atlantic salmon was extinguished through habitat destruction and through over-exploitation by a food and commercial fishery.  Attempts to re-establish Atlantic salmon through stocking have failed, and the original strain is no longer available. 

Applicability of Criteria

Criterion A: (Declining Total Population): Not applicable.
Criterion B: (Small Distribution, and Decline or Fluctuation): Not applicable.
Criterion C: (Small Total Population Size and Decline): Not applicable.
Criterion D: (Very Small Population or Restricted Distribution):  Not applicable.
Criterion E: (Quantitative Analysis): Not available.