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For the past two years, Acroloxus Wetlands Consultancy has been working closely with the Texada Stickleback Recovery Implementation Group to develop and implement a Recovery Strategy and Recovery Implementation (Action) Plan for Texada Island Sticklebacks. Texada Island Stickleback species pairs are small freshwater fish descended from the ocean-dwelling Threespine Stickleback (Gasterosteus aculeatus). They are among the rarest and most threatened species in the world. Federally listed as endangered, recovery planning for these species is mandated by law.
Distribution Of five known Stickleback species pairs, four are restricted to small lakes on Texada Island (Priest, Balkwill, Paxton and Emily Lakes). A fifth species pair is found in Enos Lake on Vancouver Island has collapsed to one hybridized population probably due to the accidental introduction of crayfish. A sixth species pair that once inhabited Lake Hadley on Lasquiti Island went extinct in the mid 1990s due to the introduction of catfish to the lake. Although biologists have surveyed many lakes along the BC, Washington, and Alaskan Coast, they have failed to discover any more of these unique fish. It is possible that species once existed in other coastal lakes but went extinct before they were discovered by biologists.
 Location of Stickleback Species Pairs, Texada Island, BC (Map by Canadian Wildlife Service)
Stickleback species pairs are of great interest to scientists because of their evolutionary history and fascinating biology. Each species pair consists of a benthic species which lives near the bottom of the lake, and a limnetic species which lives in the water column. The two species differ in appearance, diet, and habitat. Adult limnetics generally feed in the surface water away from the lake margins, where they hunt in loose schools for invertebrates and zooplankton. Adult benthics typically feed along the shallow margins of the lake for larger prey including snails, clams, dragonfly nymphs, amphipods, and chironomid larvae.
Benthic (top) and Limnetic (bottom) Stickleback Pair from Paxton Lake Recent Evolution Thought to have evolved since the end of the last glaciation, 13,000 years ago, Stickleback species pairs are among the youngest species on earth. As the evolution of new species is normally believed to take millions of years, the great speed with which these species evolved has intrigued and excited the scientific community. As glaciers retreated from coastal areas of British Columbia, the land rebounded and formed a number of small islands between Vancouver Island and the BC mainland. As the islands rose, lakes formed and gradually became brackish and then fresh water. Marine sticklebacks trapped in these lakes became adapted to a fresh water existence. No more than two species occur in any one lake, but pairs of species in different lakes seem to have evolved completely independently of other pairs. There is debate among the scientific community about whether species pairs in each lake originated from a single invasion event or a double invasion event. Researchers from the University of British Columbia are currently examining the DNA of these fish investigate this issue further.
Conservation The recent extinction of the Lake Hadley Stickleback species pair on Lasqueti Island, and the hybridization of the species pair in Lake Enos on Vancouver Island illustrates the fragility of these rare fish. The species are restricted to tiny coastal lakes surrounded by land and salt water, all of which is uninhabitable for the fist. They are dependant on humans not to destroy or degrade these lakes through their activities such as logging, land clearing, water removal, road building, or introduction of exotics. The goal of the Texada Stickleback Group is to ensure the maintenance of self-sustaining populations of stickleback species pairs, and prevent their extinction or collapse into one hybridized population. The Recovery Strategy includes a program of stewardship, education, conservation, monitoring, and research. Specific conservation actions address issues related to exotic species, water use and water quality, recreational fishing, forestry and other land uses.
Acroloxus Wetlands Consultancy. 2005. Framework for Texada Stickleback Action Plan. Hatfield, T., J. Rosenfeld, C. Murray, C. Foote, D. Jesson, J.D. McPhail, J. Richardson, D. Schluter, E. Taylor, and P. Wood. 2003. National Recovery Strategy for Stickleback Species Pairs (Gasterosteus spp.) in British Columbia. Prepared for British Columbia Ministry of Water, Land and Air Protection, and Fisheries and Oceans Canada.
Stickleback Species Pairs brochure. BC Minstry of Environment, Lands and Parks. 1999. Text by Todd Hatfield.
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