Science Advisory Report  2015/038

Recovery Potential Assessment for the Salish Sucker in Canada

Summary

• The current Canadian distribution of Salish Sucker encompasses 11 watersheds (each supporting a population or meta-population) within the Fraser Valley.  No extirpations are known to have occurred, but indirect evidence suggests that distributions and population sizes within watersheds have contracted.
• Current estimates of abundance, based on mark-recapture work, are available for parts of, or all of, seven of the eleven watersheds; there are no long term data to estimate trends in any of them.
• Salish Sucker life history characteristics (small body size, early maturation, protracted spawning period) are typical of species with high intrinsic rates of population growth, which facilitate rapid recovery from episodic mortality and colonization of newly available habitats. However, widespread habitat degradation and current habitat quality may have affected the species’ vital rates. The potential for natural recovery is limited by habitat quality.
• Severe hypoxia in summer habitats is believed to limit recovery of all populations and threaten survival of some; it is considered the predominant threat.
• Most watershed population targets proposed herein have been reduced from those in the 2012 Proposed Recovery Strategy. Total population target is proposed at 31,500 adult fish.
• The recommended level of allowable harm is two adult fish, or two percent of the lower 95% confidence limit of the most recent population estimate, whichever is greater, to a maximum of 10 adult fish per watershed per annum.
• Information on habitat and land use trajectories is needed to infer future population recovery. Given that more habitat is being lost then gained every year, future work should be directed to model habitat changes and Salish Sucker population responses to those changes.

This Science Advisory Report is from the March 23, 2015 Recovery Potential Assessment (RPA) for Salish Sucker. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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