Science Advisory Report 2018/045

Stocking Strategy for the Establishment of Self-sustaining Atlantic Whitefish Population(s) and Development of a Framework for the Evaluation of Suitable Lake Habitat

Summary

• The Atlantic Whitefish is an endangered species that is at high risk for global extinction. The only remaining source stock is from the Petite Riviére Lakes (Minamkeak, Milipsigate, and Hebb).
• The introduction of invasive predatory species (Smallmouth Bass and Chain Pickerel) throughout the remaining critical habitat of Atlantic Whitefish remains a significant and emergent threat to their continued survival. Within Hebb Lake, Atlantic Whitefish have declined below detectable thresholds since the introduction of Chain Pickerel, further reducing the species global distribution by approximately one third.
• Atlantic Whitefish population abundance within the Petite Lakes has never been quantitatively assessed and therefore abundance, relative to minimum viable population size, is unknown. The number of Atlantic Whitefish that can be safely removed from the Petite Lakes to support recovery activities is unknown.
• Range expansion efforts, whether lake-resident or anadromous, will require propagation to secure sufficient numbers of Atlantic Whitefish to meet release targets that provide a reasonable likelihood of success for establishing a self-sustaining population(s).
• Conservation release programs of related Coregonid species have been successful at establishing self-sustaining populations. Comparable egg and larvae propagation targets for Atlantic Whitefish would require, approximately 220 – 320 mature adults exhibiting the traits (i.e. size, fecundity) of the lake-resident donor population or approximately 95 - 135 mature adults using wild-caught fish maintained in a captive environment.
• Propagated Atlantic Whitefish should be released into the wild at the earliest possible life stage to reduce risks associated with domestication selection. Post-yolk sac larvae are recommended as the preferred release life stage for Atlantic Whitefish recovery efforts.
• Releases should occur incrementally as fish are produced, and should be continued until the release targets have been achieved for a suitable number of years. It is unlikely that sufficient numbers will be available to permit more than a single population for the first several years of any newly developed propagation program.
• At a minimum, release site selection criteria for freshwater-resident populations should include systems that: are free of invasive species and/or possess a barrier to upstream fish passage, maintain a pH >5.0, and are of sufficient size and depth to provide a well oxygenated coldwater hypolimnion during summer conditions. For anadromous populations, the same criteria would be generally applicable; however, a system providing direct access to the sea would be necessary.
• It is highly unlikely that objectives to establish additional freshwater populations (for survival) and the establishment of anadromous populations (for recovery) can be achieved without significant and long-term human intervention.  

This science advisory report is from the November 1-2, 2017, meeting Stocking Strategy for the Establishment of Self-sustaining Atlantic Whitefish Population(s) and Development of a Framework for the Evaluation of Suitable Lake Habitat. 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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