COSEWIC Assessment and Status Report on the "Eastslope" Sculpin (St. Mary and Milk River population) Cottus sp. in Canada
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Size and Trends
- Limiting Factors
- Existing Protection or Other Status Designations
- Special Significance of the Species
- Technical Summary
- Acknowledgements and Authorities Contacted
- Literature Cited and Biographical Summary of Report Writer
Range of Occurrence in Canada: Alberta
Extent and Area Information
Threats (actual or imminent threats to populations or habitats)
Restricted range, total area of occupancy constrained to an» 80 km stretch of the St. Mary and 220 km of the Milk River systems of Alberta (but < 1 km wide at widest section).
- Habitat loss and degradation resulting from loss of water flow due to impoundments, diversions and water removal, as well as frequent periods of drought which may become more pronounced due to global climate change
Rescue Effect (immigration from an outside source): Moderate (St. Mary River only)
The entity "Eastslope" sculpin is not listed separately by the Association for Biodiversity Information. The Columbia sculpin, Cottus hubbsi and the mottled sculpin, Cottus bairdii , are listed as follows:
Columbia sculpin, Cottus hubbsi
Mottled Sculpin, Cottus bairdii
Status and Reasons for Designation
Reasons for Designation: This species has a very restricted area of occurrence in the St. Mary and Milk rivers in Canada where it has been impacted by habitat loss and degradation from water diversion, conditions that have been exacerbated in recent years by drought.
Applicability of Criteria
Criterion A (Declining Total Population):
Not Applicable - no evidence to support overall declining population trends. However, because of the limited distribution, loss of some habitat, existing and potential threats (e.g., drought, water removal, possible dam construction on the Milk River), the species might possibly qualify as threatened under A4c.
Criterion B (Small Distribution, and Decline or Fluctuation):
Not applicable – the extent of occurrence (2600 km2) is less than 5000 km2, the area of occupancy (6 km2) is less than 500 km2, there are fewer than 5 locations, and there is evidence of decline in AO, quantity and quality of habitat and number of populations, but the rate is of decline is not known. There is some indication that populations may fluctuate in response to periodic drought conditions, however the magnitude of such fluctuations is unknown.
Criterion C (Small Total Population Size and Decline):
Not Applicable - Population size and trends not known, but no doubt exceed 1000 mature individuals (there is no quantitative estimate), however there is no evidence of overall decline although increases and decreases are known for various areas.
Criterion D (Very Small Population or Restricted Distribution):
Meets the criterion for Threatened D2, i.e., restricted distribution, known only from 3 locations and the area of occupancy is less than 6 km2. The species is prone to the effects of agricultural practices that alter stream flows for irrigation and to drought conditions resulting from global warming.
Criterion E (Quantitative Analysis):
Not Applicable – data not available.
- Date Modified: