Science Advisory Report 2020/039

Recovery Potential Assessment of Warmouth (Lepomis gulosus) in Canada

Summary

• In Canada, the current and historic distribution of Warmouth is limited to just three locations (Point Pelee, Rondeau Bay, and Long Point Bay) in the Lake Erie drainage (Figure 1). Results of a population status assessment ranked all three populations as Poor.
• Warmouth uses shallow (< 2 m), heavily-vegetated embayments of lakes, slow-moving streams and wetlands. Important habitat features include submergent and emergent vegetation as well as soft bottom substrates consisting of sand, silt, clay, or organic material.
• To achieve 99% probability of persistence, given a 15% chance of catastrophic decline (50% reduction in abundance) per generation, there would need to be ~ 6,000 adults for a minimum viable population (MVP) using an independent correlation structure. The minimum area required to support this population (i.e., minimum area for population viability [MAPV]) is approximately 41 ha. The effects of intra-annual correlation in vital rates were explored and were found to have a large impact on MVP estimates.
• Warmouth are most sensitive to perturbations to the adult stage. Chronic annual mortalities of greater than 24.7% to the adult stage or 13.2% to all age-classes is likely to cause population decline.
• The greatest threats to Warmouth populations are aquatic vegetation removal, wetland draining for agricultural purposes, and natural system modifications due to the establishment of invasive plants.
• For Canadian populations, knowledge gaps exist related to Warmouth life cycle, distribution, habitat needs, and population abundance. This includes uncertainty with population trajectories and age-specific mortality used in population modelling. Research is required to identify spawning and nursery grounds and to identify the spatial extent of suitable Warmouth habitat. There is also a need for causative studies to evaluate the impact of threats on Warmouth populations.

This Science Advisory Report is from the December 12th, 2018 Recovery Potential Assessment – Warmouth (Lepomis gulosus). Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2020/039 (PDF, 749 KB)

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