How temperature affects timing and duration of yellow perch spawning in the Indiana waters of Lake Michigan

Adult yellow perch were collected from the Indiana waters of Lake Michigan during 2009, 2011, and 2012 to estimate the length and timing of the yellow perch spawning season. Sampling was conducted using gill nets at three zones near East Chicago, Burns Harbor, and Michigan City from May to August in 2009 and 2011; however, sampling was conducted twice in April before continuing from May to August in 2012. After collection, yellow perch were measured, counted, and sexed and then the maturity state was determined. Logistic regression was used to model the proportion of post-spawn (spent) fish over time for each year. The resulting models estimated the timing and duration of yellow perch spawning and allowed the determination of peak spawn (50% spent) for each year. We found that yellow perch spawning started when mean daily water temperatures at the sample sites reached approximately 11 degrees C and lasted two to four weeks with cessation occurring when water temperatures exceeded 13 degrees C. In 2009 and 2011, spawning began in mid-May and was finished in early June, while in 2012 spawning started in early May and finished before June. These differences were likely in response to unseasonably warm lake temperatures caused by record high springtime air temperatures in the Great Lakes region. These findings suggest global climate change will alter yellow perch reproductive cycles.