Greenside darter (Etheostoma blennioides) COSEWIC assessment and status report: chapter 11

Technical Summary

Etheostoma blennioides

greenside darter – dard vert

Range of Occurrence in Canada:

Ontario

Extent and Area Information

Extent of occurrence (EO)(km²)
~38,400 km² [calculated from Figure 4]
Specify trend in EO
increasing
Are there extreme fluctuations in EO?
no
Area of occupancy (AO) (km²)

32 km² [calculated from Figure 1]

  • Bayfield River <1 km²
  • Ausable River – 160 km x 10 m = 1.6 km²
  • Sydenham River – 200 km x 10 m = 2.0 km²
  • Lake St. Clair – 10 km²
  • Thames River – 387 km x 30 m = 11.6 km²
  • Detroit River ~1 km²
  • Big Otter Creek 1
  • Big Creek < 1 km²
  • Grand River – 210 km x 30 m = 6.3 km²]
Specify trend in AO
increasing
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
10 tertiary watersheds (76 element occurrences)
Specify trend in #
increasing
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
increasing

Population Information

Generation time (average age of parents in the population)
2 years
Number of mature individuals
Unknown, but probably more than 10,000
Total population trend:
% decline over the last/next 10 years or 3 generations.
n/a – increasing population trend
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
No
Specify trend in number of populations
increasing
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
population sizes are unknown

Threats (actual or imminent threats to populations or habitats)

No immediate threats, potential threats include:

  • Sediment and nutrient inputs associated with agricultural activities
  • Contaminants from spills and runoff
  • Urban growth in the Thames and Grand River watersheds
  • Predation and competition from introduced round goby

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
USA : Michigan (S4), Ohio (SNR). Pennsylvania (S5), New York (S3) – considered a common species in some adjacent U.S. jurisdictions.
Is immigration known or possible?
possible
Would immigrants be adapted to survive in Canada?
yes
Is there sufficient habitat for immigrants in Canada?
yes
Is rescue from outside populations likely?
Possibly

Quantitative Analysis

insufficient information for quantitative analysis [provide details on calculation, source(s) of data, models, etc]

Current Status

  • COSEWIC: Special Concern (1990), Not at Risk (2006)
  • SARA: Special Concern – Schedule 3
  • Ontario: Special Concern
  • General Status – Canada: Sensitive
  • General Status – Ontario: Sensitive

Status and Reasons for Designation

Status: Not at Risk

Alpha-numeric code:  Not Applicable

Reasons for Designation: Recent surveys have shown that the species is widespread and abundant in the Ausable, Sydenham and Thames rivers as well as Lake St. Clair. The total Canadian population has also increased through the recent colonization of the Bayfield River, Big Otter Creek, Detroit River, and the Grand River. Rescue of greenside darter populations in Canada is possible from Michigan populations.

Applicability of Criteria

  • Criterion A: (Declining Total Population): Not applicable. EO, AO and population size appear to be increasing.
  • Criterion B: (Small Distribution, and Decline or Fluctuation): Not applicable.  Although the species is known to occur in 10 watersheds there is no evidence of decline.
  • Criterion C:(Small Total Population Size and Decline): Not Applicable.  Population size, although unknown, probably exceeds threshold and is likely increasing.
  • Criterion D: (Very Small Population or Restricted Distribution): Not Applicable.  AO exceeds threshold and is likely increasing; population size, although unknown probably exceeds 10,000 and is also increasing.
  • Criterion E: (Quantitative Analysis): Not Applicable.  Insufficient information for quantitative analysis.

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