In large lakes like Lake Michigan, larval fish are carried passively to different parts of the lake by currents created by the interaction of temperature, wind, and water. However, as the climate changes, the timing of when fish hatch may no longer align well with the best timing for their transport or food availability (like free floating algae).  

To understand potential timing mismatches, Midwest CASC-supported researchers simulated hatch and transport of fish larvae in Lake Michigan. The researchers evaluated patterns of timing overlap between suitable water temperatures and prey availability and considered the potential consequences of changes in hatch time in the future. They found that more fish larvae were transported offshore earlier in warm years than in cool years. In warmer years, the fish larvae tend to be carried earlier to offshore parts of the lake that are less suitable for their growth and development. Consequences of these timing mismatches could impact future fish recruitment and population sizes if warmer years occur more frequently. 

Species such as the yellow perch, which emerges in mid- to late-spring, and the alewife, which emerges in early summer, may have varied responses to changing water and climate conditions. This Midwest CASC-supported study provides insights into how changing conditions may affect species that emerge at different times of the year. 

This research was supported by the Midwest CASC Project titled “Understanding and Forecasting Potential Recruitment of Lake Michigan Fishes.”