Navigating cisco restoration in Keuka Lake, New York

Alex Koeberle (PhD student), Suresh Sethi, Lars Rudstam, Evan Cooch, and Brad Hammers (NYSDEC), funded by NYSDEC 

Cisco (Coregonus artedi) constituted the historical prey fish (mid-trophic) population in Keuka Lake. Yet, by the mid-1990s, the Cisco population was considered extirpated by lake managers with introduced Alewife and Rainbow Smelt among the most important drivers of their extirpation. While Rainbow Smelt gillnet catches declined in lake-wide surveys since the 2000s, managers observed a crash in Alewife catches after 2015. Despite these declines in prey fish, Keuka Lake supports an abundant, wild-reproducing Lake Trout population and popular sport fishery among anglers. This has prompted NYSDEC to implement ongoing Cisco reintroductions to stabilize Keuka Lake’s mid trophic fish assemblage and improve recovery of the lake ecosystem. In 2024, we conducted a population viability analysis to evaluate the likelihood of re-establishing a native Cisco population to Keuka Lake. We applied in situ estimates of juvenile fish survival from an acoustic telemetry study and in situ adult mortality rates estimated from a long-term catch dataset prior to their extirpation. We found that recovery is unlikely given two demographic processes: 1) high mortality of stocked juvenile fish upon release, and 2) high wild mortality in current lake conditions. Insights from these lake-specific datasets proved valuable for accurately assessing restoration success. Additionally, we are developing a food web model for Keuka Lake to compare the structure and energy flows among pre- and post-Alewife collapse and future food web scenarios. We anticipate that this research will provide opportunities for managers to improve fisheries conservation in Keuka Lake as well as comparable lakes with fish restoration throughout New York State.