Stickleback species pairs final recovery strategy: chapter 2
Species Information
The status report and assessment summary for stickleback species pairs is available from the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) Secretariat).
Common Name: Threespine stickleback, species pairs denoted as “limnetic” and “benthic” species.
Scientific Name: Gasterosteus spp. (no formal taxonomic designation for the species pairs, although there is strong evidence that indicates the forms are true biological species independently derived from marine Gasterosteus aculeatus)
COSEWIC Assessment Summary:
Enos Lake species pair. November 2002
Hadley Lake species pair. May 2000
Paxton Lake species pair. May 2000
Vananda Creek (Balkwill, Priest and Emily Lakes) species pair. May 2000
COSEWIC Status:
Enos Lake species pair. Endangered
Hadley Lake species pair. Extinct
Paxton Lake species pair. Endangered
Vananda Creek species pair. Endangered
SARA Status:
Enos Lake species pair: Endangered, January 2005
Hadley Lake species pair: Extinct
Paxton Lake species pair: Endangered, June 2003
Vananda Creek species pair: Endangered, June 2003
COSEWIC Reason for Designation:
Enos Lake species pair. These fish are restricted to a single, small lake on Vancouver Island are experiencing severe decline in numbers due to deteriorating habitat quality and the introduction of exotics. Since the COSEWIC designation, the species pair has collapsed into a hybrid swarm. A captive breeding program is ongoing with pure limnetics and benthics.
Hadley Lake species pair. This Canadian endemic fish was known only from Hadley Lake, Lasqueti Island, British Columbia. It was lost as a result of nest predation by the introduced brown bullhead.
Paxton Lake species pair. This unique Canadian endemic is impacted by habitat loss and/or degradation from human disturbance. It is in danger of extinction by the introduction of exotic species.
Vananda Creek species pair. This unique Canadian endemic is impacted by habitat loss and/or degradation from human disturbance. It is in danger of extinction by the introduction of exotic species.
Canadian Occurrence: Stickleback species pairs are restricted to specific coastal lakes in the Georgia Basin, British Columbia. Present occurrence is four lakes (in two watersheds) on northern Texada Island. Historically, species pairs also existed in Hadley Lake, Lasqueti Island, and in Enos Lake, Vancouver Island. The species pair in Hadley Lake went extinct following introduction of brown bullhead, and the species pair in Enos Lake has been reduced to a hybrid swarm following introduction of signal crayfish.
COSEWIC Status history:
Enos Lake species pair. Original designation (including both Benthic and Limnetic species) was Threatened in April 1988. Split into two species when re-examined. Designated Endangered in November 2002. Last assessment based on an update status report.
Hadley Lake species pair. Designated Extinct in April 1999. Status confirmed in May 2000. Last assessment based on an existing status report.
Paxton Lake species pair. Designated Threatened in April 1998. Status re-examined and confirmed in April 1999. Status re-examined and uplisted to Endangered in May 2000. Last assessment based on an existing status report.
Vananda Creek species pair. Designated Threatened in April 1999. Status re-examined and uplisted to Endangered in May 2000. Last assessment based on an existing status report.
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