Lake Ontario and Great Lakes kiyi COSEWIC assessment and status report: chapter 12

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Technical Summary: Coregonus kiyi kiyi

Coregonus kiyi kiyi (C. k. kiyi)

Upper Great Lakes Kiyi – kiyi du secteur supérieur des Grands Lacs

Quantitative Analysis

Data not available

Existing Status – C. kiyi kiyi

• Nature Conservancy Ranks (NatureServe 2005)
  • Global – G3
  • National
    • US – N3
    • Canada N3?
  • Regional
    • US: IN – S1, MI – S3, MN – S3, NY – SX, WI – S2S3
    • Canada: ON – S3
• Other
  • IUCN – VU
  • AFS – T
  • Wild Species 2000 (Canadian Endangered Species Council 2001)
    • Canada – 1
    • Ontario – 1
  • COSEWIC– Special Concern (May 2005)

Status and Reasons for Designation

Status:  Special Concern

Alpha-numeric Code: Not Applicable

Reasons for Designation: Currently found only in Lake Superior, the subspecies has been extirpated from lakes Huron and Michigan, as the result of a complex of factors, which included exploitation and introduced exotic species. The extirpation in lake Huron’s and Michigan occurred more than three generations in the past. The remaining population in Lake Superior appears to be stable, and supports a small, regulated fishery. Other threats, such as the introduction of exotic species, which impacted populations in the lower lakes do not appear to be important in Lake Superior.

Applicability of Criteria

• Criterion A (Declining Total Population):  Not applicable - The subspecies has been extirpated from over 50% of its former extent of occurrence in Canada (as well as from Lake Michigan, the last recorded occurrences in lakes Huron, and Michigan were in 1973 and 1974 respectively). However, the decline in area of occupancy and extent of occurrence did not occur within the last 3 generations or 10 years. The subspecies persists in Lake Superior; however, trends are not known. Overfishing, and competition with exotic species, which are thought to have caused the demise of the subspecies in lakes Huron and Michigan, are unlikely to have as marked an impact in Lake Superior. However, one must keep in mind the rapid declines in the other lakes, which occurred over a short period of time (~ 15 years in Lake Ontario) and that this subspecies could precipitously decline to extinction (as have others of the Great Lakes ciscos) based on unknown concerns.
• Criterion B (Small Distribution, and Decline or Fluctuation): Not applicable - The present extent of occurrence (82,000 km²) and area of occupancy (58,000 km²) are well above the threshold for Endangered or Threatened (B1 or B2). There is no evidence to suggest that the subspecies is severely fragmented, and the number of locations within Lake Superior is unknown, but certainly greater than the minimal threshold of 10 for Threatened. Similarly, there are no data to indicate extreme fluctuations or continuing decline in number or extent and quality of habitat.
• Criterion C (Small Total Population Size and Decline): Not Applicable - Estimates from eastern Lake Superior in 2000-2001 indicate between 22 and 330 tonnes of the species in the deepest parts of Canadian waters. At an average size of 0.17kg (Scott and Crossman 1998) this equates to 130,000 to 2,000,000 individuals, which exceeds the threshold of 10,000 individuals (which is meaningless for such a species at any rate).  However, this is based on an average size and provides no information about what proportion comprise mature individuals, but it would be considerably less. Data are simply not available to provide any information on population trends in Lake Superior despite the fact that recent levels of harvest are about 10% of the estimated biomass.
• Criterion D (Very Small Population or Restricted Distribution): Not Applicable - The subspecies exceeds the threshold values of 1000 mature individuals, 20 km² for area of occupancy, and 5 sites or locations.
• Criterion E (Quantitative Analysis): Data are not available.