Science Advisory Report 2009/077
Recovery potential assessment of Vancouver Island lamprey (Lampetra macrostoma Beamish)
Summary
- The species has been reported in Cowichan Lake and Mesachie Lake, in south-central Vancouver Island. Neither total abundance nor abundance specific to the various habitats have been reliably estimated. COSEWIC (2000) provides a population abundance estimate of 1,000-2,000 adults.
- Results of a trapping study in Mesachie Lake suggest the population may have declined in the last fifteen years. Thirty years of informal records from an annual fishing derby on Mesachie Lake suggest decreased catch-per-unit-effort in recent years.
- Adults are not believed to guard their egg nests but they expend energy in creating spawning nests by carrying gravel in their mouths. Spawning nests should thus be considered short-term residences. The ammocoete stage has a residence requirement for silty substrate in which to construct burrows.
- Threats to survival or recovery from human impacts include incidental angling mortality in the recreational fishery, residential development and recreation, forestry, water withdrawal and prey availability.
- The low and highly uncertain population abundance estimates, the noted reports of a recent decline in catch indices and the restricted, endemic population range of the species indicate that there is no scope for human-induced mortality.
- The locations of principal spawning and ammocoete rearing sites have been identified in the better studied Mesachie Lake population. It is recommended that these areas be identified as potential critical habitat. Similar habitat types in the less studied Cowichan Lake are likely important but where there is uncertainty in the use and specific boundaries of the habitat, they are not recommended as critical habitat at this time.
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