Terms of Reference

Assessment of the Population Abundance for Lake Utopia Rainbow Smelt, Large-Bodied Population

Regional Peer Review - Maritimes Region

November 6-7, 2024

Dartmouth, NS

Chairperson: Lei Harris

Context

Lake Utopia is part of the Magaguadavic River watershed in southwestern New Brunswick. The native Rainbow Smelt (Osmerus mordax) inhabiting Lake Utopia consists of two sympatric morphologically, ecologically, and genetically differentiated populations: a small-bodied population (SbP) and a large-bodied population (LbP). SbP and LbP were listed as threatened under SARA in 2003 and 2019, respectively. In 2018, both populations were reassessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as endangered and subsequently reclassified under SARA in 2020.

Former CSAS processes (DFO 2016b, 2018, 2024) have reviewed and updated the LbP abundance objective, the minimum fork length for distinguishing the two populations, the maximum level of allowable harm that LbP can sustain without jeopardizing the species survival or recovery, whether abundance estimates have met the minimum target, and indicators of whether the genetic objective is being met. A new recovery abundance target of “A recovery abundance target of 5,000 adults in Mill Lake Stream observed on nights of peak spawning would be consistent with the broad goal of maintaining current population of LURS-LbP” was recommended and considered feasible for this population (DFO 2018). The threshold minimum fork length used to distinguish LbP from SbP was recommended to be reduced to 130 cm from previous thresholds of 143 (DFO 2018) and 170 (DFO 2011) based on genetic analysis (DFO 2024). LbP maximum nightly spawner abundance estimates declined over 4 years from 23,421 in 2014 to 12,201 in 2017 to 6,736 in 2018; however, spawning runs overall have exceeded the recovery abundance target in each of these years. The high variability of LbP spawner abundance estimates, declining minimum fork length criterion required to distinguish LbP smelt, a higher rate of gene flow from SbP into LbP, and the presence of hybrids, warrant further sampling, analyses, and review to track these trends and to determine if the LbP recovery abundance and genetic objectives are being met.

The DFO Species at Risk Program has requested an updated LbP population abundance estimate from DFO Science to assess progress against the abundance objectives of the Recovery Strategy.

Objectives

• Provide an updated population abundance estimate for LURS-LbP in Mill Lake Stream based on sampling conducted in 2023 and on genetic analysis of these samples.
• Has the recommended updated recovery abundance objective of 5,000 individuals occupying Mill Lake Stream on at least one night been met?
• Review the minimum fork length criterion for distinguishing LURS-LbP from LURS-SbP based on the new genetic analysis.

Expected Publications

• Science Advisory Report

Expected Participation

• DFO Science and Ecosystem Management
• Academics
• Indigenous Organizations
• Environmental Non-government Organizations

References

• COSEWIC. 2018. COSEWIC assessment and status report on the Rainbow Smelt (Osmerus mordax), Lake Utopia large-bodied population and the Lake Utopia small-bodied population, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xvi + 40 pp.
• DFO. 2011. Recovery Potential Assessment for Lake Utopia Rainbow Smelt (Osmerus mordax) Designatable Units. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2011/004.
• DFO. 2016a. Recovery Strategy for the Lake Utopia Rainbow Smelt (Osmerus mordax), Small-bodied Population (sympatric with the Large-bodied Population), in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada. Ottawa. viii + 57 pp.
• DFO. 2016b. Estimating Lake Utopia Rainbow Smelt (Osmerus mordax) Spawner Abundance and Allowable Harm. DFO Can. Sci. Advis. Sec. Sci. Resp. 2016/024.
• DFO. 2018. Updated Estimate of Lake Utopia Rainbow Smelt (Osmerus mordax), Large-bodied Population, Spawner Abundance and Allowable Harm. DFO Can. Sci. Advis. Sec. Sci. Resp. 2018/019.
• DFO. 2020. Action Plan for the Lake Utopia Rainbow Smelt (Osmerus mordax), Small-bodied Population (Sympatric with the Large-bodied Population), in Canada. Species at Risk Act Action Plan Series. Fisheries and Oceans Canada, Ottawa. vi+ 36 pp.
• DFO. 2024. Lake Utopia Rainbow Smelt, Large-bodied Population (LURS-LbP): Updated Population Abundance and Genetic Analyses. DFO Can. Sci. Advis. Sec. Sci. Resp. 2024/031.