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Spotted gar (Lepisosteus oculatus) COSEWIC assessment and status report: chapter 11

Technical Summary

Lepisosteus oculatus

spotted gar – lépisosté tacheté

Range of Occurrence in Canada:
ON

Extent and Area information

extent of occurrence (EO) (km²)Excludes introduced Bay of Quinte records.
5,000
specify trend :
Stable?
are there extreme fluctuations in EO (> 1 order of magnitude)?
No

area of occupancy (AO) (km²)
Area of ponds where captured in Point Pelee. Area of suitable habitat (vegetated, less than 5 m deep) in Long Point (including Big Creek wetland) and Rondeau bays.

specify trend (decline, stable, increasing, unknown) :
Stable?
are there extreme fluctuations in AO (>1 order magnitude)?
Stable?
number of extant locations :
3
specify trend in # locations (decline, stable, increasing, unknown) :
Stable
are there extreme fluctuations in # locations (>1 order of magnitude)?
no
habitat trend:  specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :
Unknown

Population information

generation time (average age of parents in the population) (indicate years, months, days, etc.) :
8 years?
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) :
Unknown
total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :
Unknown
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)
are there extreme fluctuations in number of mature individuals
(>1 order of magnitude)?
Unknown
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)?
Yes

list each population and the number of mature individuals in each

specify trend in number of populations (decline, stable,
increasing, unknown) :
Unknown for all populations.
are there extreme fluctuations in number of populations
(>1 order of magnitude)?
Unknown for all populations.

Threats

Rescue Effect (immigration from an outside source):
Low
does species exist elsewhere (in Canada or outside)?
Yes
status of the outside population(s)?
(for Lake Erie populations only)
MI - S2S3;
PA, OH - S1
is immigration known or possible?
Unknown, Unlikely
would immigrants be adapted to survive here?
yes
is there sufficient habitat for immigrants here?
Probably

Quantitative Analysis

Existing Status

Status and Reasons for Designation

Status: Threatened

Alpha-numeric Code: D2

Reasons for Designation: This species has a very limited range in Canada where it is only known from three coastal wetlands in Lake Erie. Although its distribution is likely limited by temperature, some of the shallow vegetated habitats that it requires for all life stages are subject to the impacts of siltation, dredging, filling, and aquatic vegetation removal and harbour improvements.

Applicability of Criteria

Criterion A (Declining Total Population): Not applicable -- Current populations are apparently stable and the historic loss of one population (Lake St. Clair -- last observed in 1962) occurred more than three generations (24 years) ago.  Although the species is also apparently extirpated from the Bay of Quinte in Lake Ontario, it is thought that its presence there was the result of an introduction and there was only ever one individual found.  Due to lack of recent declines, this species does not qualify under this criterion.

Criterion B (Small Distribution, and Decline or Fluctuation):  Not applicable -- The area of occupancy (52 km²km²) is below the minimum threshold for endangered and the extent of occurrence (5000 km²km²) is right at the threshold between threatened and endangered.  Although there are only three extant locations, there are no continuing declines in population size, occurrences or habitat nor are there extreme fluctuations.  Therefore the species does not qualify under this criterion.

Criterion C (Small Total Population Size and Decline):  Not applicable -- The number of mature individuals is not known, but even if numbers were small enough to meet the thresholds for threatened or endangered, required declines do not exist to apply this criterion.

Criterion D (Very Small Population or Restricted Distribution):  Qualifies for Threatened, D2, based on its occurrence at three locations, and threats to habitat.

Criterion E (Quantitative Analysis):  Data are not available to apply this criterion.

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