The fish known collectively as “stickleback species pairs” are small, freshwater fish descended from the marine threespine stickleback (Gasterosteus aculeatus). Their recent and unique evolutionary history has been of considerable scientific interest and value. Stickleback species pairs were known to exist in four watersheds in the Georgia Basin, British Columbia: two watersheds on Texada Island, and one each on Lasqueti and Vancouver Islands. Within the last decade the species pair on Lasqueti Island has been declared extinct, and the species pair in Enos Lake has collapsed into a single hybrid swarm. The present global range is restricted to four small lakes in two watersheds on northern Texada Island. Stickleback species pairs consist of separate benthic and limnetic forms. The pairs spawn in littoral areas in the spring, rear in littoral and pelagic areas in spring and summer, and overwinter in deep water habitats during the fall and winter. The lakes in which pairs developed have abundant and productive littoral and pelagic habitat, and a simple fish community comprised only of stickleback and cutthroat trout. Specific environmental conditions required to maintain abundance and reproductive isolation of limnetic and benthic species include water quality, light transmission, nutrients, littoral habitat, and macrophytes. The greatest known threats to stickleback species pairs are introductions of exotic species, and impacts from water management and land use. Some proposed features of critical habitat, a collection of environmental features whose alteration or loss will lead to reduction in abundance to an unviable population level or breakdown of reproductive barriers sufficient to cause collapse into a hybrid swarm, are described in the strategy. The goal of the recovery strategy is to secure the long-term viability of all remaining populations of stickleback species pairs.
National Recovery Team for Stickleback Species Pairs.. 2007. Recovery Strategy for Paxton Lake, Enos Lake, and Vananda Creek Stickleback Species Pairs (Gasterosteus spp.) in Canada. Ministry of Environment. Recovery Plan
Topic: Recovery Planning
Keywords: SARA, endangered, species, recovery, threatened, species at risk