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Science Response 2021/037

Lake Utopia Rainbow Smelt, Small-bodied Population (LURS-SbP) Population Abundance and Allowable Harm Estimate

Context

Lake Utopia is part of the Magaguadavic River watershed in southwestern New Brunswick. Two populations of Lake Utopia Rainbow Smelt (LURS) co-exist in Lake Utopia, a small-bodied form (LURS-SbP) and a large-bodied form (LURS-LbP). Lake Utopia represents one of the only three confirmed occurrences in Canada where genetically divergent smelt populations co-exist (Taylor and Bentzen 1993, Bradbury et al. 2011).

The LURS-SbP was originally designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in April 1998 and was listed under the Species at Risk Act (SARA) as Threatened in June 2003. The rationale for the designation was:

the population is part of a genetically divergent sympatric pair of Osmerus that is endemic to a single lake in Canada with an extremely small index of an area of occupancy (6 sq. km). It spawns in only three (3) small streams in the watershed and could quickly become extinct through degradation of spawning streams from increasing development around the lakeshore and impacts of the dip-net fishery. This population is threatened by the introduction of exotic species and by increasing eutrophication. (COSEWIC 2008)

A Recovery Potential Assessment (RPA) for Lake Utopia Rainbow Smelt (Osmerus mordax) (both SbP and LbP) was undertaken in 2010 (DFO 2011), and SbP Recovery Strategy developed (DFO 2016). LURS-SbP was re-assessed as Endangered by COSEWIC in 2018 (COSEWIC 2018). The most recent abundance estimate for the LURS-SbP is from 2009 (DFO 2011). Therefore, an update of this information, along with further investigation of new sampling information to address questions related to the relative contribution of the spawning streams to the population productivity of the LURS-SbP, is needed.

Science advice on the population status and allowable harm level for LURS-SbP was requested by the Species at Risk Program (SARP), Maritimes Region. This request intended to seek updated information on LURS-SbP abundance estimate, abundance target, and allowable harm, where available. The objectives were:

  • Provide an updated population abundance estimate for LURS-SbP in Second Brook, Unnamed Brook, Smelt Brook, and Mill Lake Stream.
  • Evaluate the relative contribution of each of the previously mentioned spawning streams to the overall productivity of LURS-SbP.
  • Review, and update as necessary, the interim recovery-abundance target that was identified in the Recovery Strategy (DFO 2016).
  • Review, and update as necessary, the current allowable-harm level that LURS-SbP can sustain without jeopardizing survival or recovery.
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    The request for advice submitted by SARP sought updated information on population abundance; however, it was noted that estimates of absolute population abundance were not possible and available data are not representative of the entire SbP population. Rather, the abundance estimates presented within this document represent stream specific nightly estimates of LURS-SbP abundance.

    This Science Response Report results from the Regional Science Response Process of November 19, 2019, for Lake Utopia Rainbow Smelt, Small-bodied Population (LURS-SbP) Population Abundance and Allowable Harm Estimate.

    Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.

    Science Response 2021/037 (PDF, 632 KB)

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