Environmental influences on the size and recruitment of inland Cisco populations in three Minnesota Sentinel lakes.

This article examines how environmental and biological factors influence the size structure and recruitment success of inland Cisco (Coregonus artedi) populations in three Minnesota lakes—Carlos, Elk, and Ten Mile—over a seven-year period. Using hydroacoustic sonar, gill nets, zooplankton sampling, and temperature and dissolved oxygen profiling, the study found that zooplankton prey availability, particularly cyclopoid copepod densities, and oxythermal habitat conditions (measured as growing degree-days at the temperature where dissolved oxygen is 3.0 mg/L, or GDD at TDO3) significantly affect Cisco maximum size and age-0 density. Internal population dynamics, such as age-1+ Cisco biomass, also correlated with recruitment variability. The findings highlight the importance of lake-specific thermal and biological conditions in shaping Cisco populations, providing insights for fisheries management regarding the vulnerability of this key forage species amid environmental changes like climate warming and invasive species.