Grass pickerel (Esox americanus vermiculatus) COSEWIC assessment and status report: chapter 13

Technical summary

Esox americanus vermiculatus
Grass Pickerel

Brochet Vermiculé

Ontario, Quebec


Extent and area information

Extent of occurrence (EO) (from Figure 3 , includes land area).
100 000 km 2
Trend in EO.
Stable
Are there extreme fluctuations in EO (> 1 order of magnitude)?
No

Area of occupancy (AO) (based on stream lengths in km).

  1. Severn River - Sparrow to Bass Lake - ca 26 km2
  2. Old Ausable Channel - 0.5 km2
  3. Lake St. Clair (incl. Walpole Island, Little Bear Creek, Sydenham River) - ca 260 km2
  4. Point Pelee ca 4 km2
  5. Long Point ca  140 km2
  6. Lower Grand River ca 1.9 km2
  7. Upper Niagara River tributaries, Welland River drainage, and Point Abino - ca 1.3 km2
  8. Twenty Mile Creek ca 1 km2
  9. Eastern Lake Ontario & upper St. Lawrence River (incl. Jones Creek, upper Gananoque) - ca 100 km2
  10. Lake St. Francis to Lac St-Louis. - ca 150 km2
Total AO – ca 685 km 2
Trend in AO (3 locations in the upper Niagara Ontario now have no suitable habitat and no pickerel, and there is a general decline in the AO in Quebec where 1 location may be lost = 22% of AO)
Decline
Are there extreme fluctuations in AO (> 1 order of magnitude)?
No
Number of extant locations (10 locations which may represent more than 10 populations)
10
Trend in # locations.
Decline
Are there extreme fluctuations in # locations (>1 order of magnitude)?
No
Habitat trend.
Some decline


Population information

Generation time (average age of parents in the population).
3-4 years
Number of mature individuals (capable of reproduction) in the Canadian population.
Unknown
Total population trend:
Decline in some areas
If decline, % decline over the last/next 10 years or 3 generations, whichever is greater.
Unknown
Are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?
Unknown
Is the total population severely fragmented?
Yes. The populations in 9/10 areas are significantly isolated from one another
List each population and the number of mature individuals in each.

Listed by location, there may be more than one population at locations 1, 3, 7, 9 and 10. There may be 3 populations at location 10 – Lac St-François, Coteau and Lac St-Louis. The number of mature individuals at any one location is not known, but would certainly not be large, perhaps in the 10s for the single population locations and in the 100s or low thousands for eastern Lake Ontario and the upper St. Lawrence.
  1. Severn River
  2. Old Ausable Channel
  3. Lake St. Clair (incl. Walpole Island, Little Bear Creek)
  4. Point Pelee
  5. Long Point
  6. Lower Grand River
  7. Upper Niagara River (including Welland River drainage)
  8. Twenty Mile Creek
  9. Eastern Lake Ontario & upper St. Lawrence River (incl. Jones Creek, upper Gananoque)
  10. Lake St. Francis to Lac St-Louis
Specify trend in number of populations (decline, stable, increasing, unknown).
Stable
Are there extreme fluctuations in number of populations (>1 order of magnitude)?
No


Threats (actual or imminent threats to populations or habitats)

  • urbanization and agriculture practices through effects on reduction in flow and channelization and pollution through herbicides
  • siltation
  • removal of vegetation
  • low water levels caused by water extraction, and drought
  • diversion of cold or cool water into pickerel habitat
  • destruction and degradation of wetland habitat


Rescue effect (immigration from an outside source)

Does species exist elsewhere (in Canada or outside)?
Yes (outside)
Status of the outside population(s)?

Only neighbouring populations – see below for status of other US locations
New York (S4)
Pennsylvania (S4)
Ohio (S?)
Michigan (S5)
Is immigration known or possible?
Yes
Would immigrants be adapted to survive here?
Yes
Is there sufficient habitat for immigrants here?
Yes


Quantitative analysis

Not applicable


Existing status

Nature Conservancy Ranks (Naturserve 2003)
Global –G3

National
US – N5
Canada – N4

Regional
US: Alabama – S5, Alaska – S?, Arkansas – S4, Colorado – SE, Connecticut – S4, Delaware – S5, Florida – S?, Georgia – S4S5, Illinois – S5, Indiana – S4, Iowa – S3, Kentucky – S4S5, Louisiana – S5, Maine – S?, Maryland – S5, Massachusetts – S5, Michigan – S5, Mississippi – S5,
Missouri – S?, Nebraska – S4, New Hampshire – S4, New Jersey – S5, New York – S4, North Carolina – S5, Ohio – S?, Oklahoma – S5, Pennsylvania – S4,
Rhode Island – S5,  South Carolina – S?, Tennessee – S5, Texas – S3, Vermont – S4, Virginia – S4, Washington – SE, West Virginia – SU, Wisconsin – S4
Canada: Ontario – S3, Quebec – S4

Wild Species 2000 Canadian Endangered Species Council 2001)
Canada – NA
Ontario – 3, Quebec – 2

Committee on the Status of Endangered Wildlife in Canada (COSEWIC) – Special Concern (May 2005)


Status and reasons for designation

Status: Special concern
Alpha-numeric code: Met criterion for Threatened, B2ab(ii,v), but designated Special Concern because there is a rescue effect and the species is not likely to become Endangered or Extirpated in the near future.


Reasons for Designation: A subspecies known from 10 locations between Lake St. Louis, Quebec and Lake Huron, Ontario. Its usual habitat is shallow water with abundance of aquatic vegetation. An overall decline of approximately 22% in the area of occupancy has been observed. This decline appears to be related to degradation and loss of habitat due to channelization and dredging operations in wetland habitats where this species occurs.


Applicability of criteria

Criterion A (Declining Total Population): Not Applicable – although some decline has occurred in about 22% of the Area of Occupancy at 3 of 10 locations, and there are indications of continuing decline in these areas, threshold values are not met.

Criterion B (Small Distribution, and Decline or Fluctuation): The area of occupancy (683 km2) is below the minimum threshold for Threatened, and decline has occurred at 3 of 10 locations and is continuing to occur. Therefore qualifies for threatened B2a,b(ii-v).

Criterion C (Small Total Population Size and Decline): Not Applicable -- Total population size is unknown but presumed to be >10 000. Therefore, does not qualify under this criterion.

Criterion D (Very Small Population or Restricted Distribution): Not Applicable -- Number of individuals unknown but presumed to be >10 000. Area of occupancy and number of extant locations are greater than threshold limits.

Criterion E (Quantitative Analysis): Not Applicable.

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