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Understanding and Forecasting Potential Recruitment of Lake Michigan Fishes

Yellow perch and alewife are ecologically, economically, and culturally important fish species in Lake Michigan whose populations support recreational and commercial fisheries. However, both of these species’ populations have been in decline for over 20 years. This project seeks to understand the factors affecting variability in offspring survival of yellow perch and alewife in Lake Michigan in order to project survival under scenarios of future climate change. Like other fish species, yellow perch and alewives produce huge numbers of small offspring, but most die early in life. Small changes in survival at this early stage can have a strong impact on the number of fish that ultimately contribute to fisheries. Recruitment of young fish (i.e. surviving the first 60 days of life) is known to vary widely from year to year and has been correlated with a number of different climate conditions. However, the exact causes underlying past recruitment variation are generally unknown and the consequences of future climatic conditions on potential fish recruitment are unclear. Researchers will evaluate factors affecting yellow perch and alewife recruitment variability using a series of models. These factors include past observed weather conditions and future projections of local climatic conditions. The models will simulate future water temperatures and currents, light levels, and zooplankton prey, which all affect feeding and movement of young fish. Additionally, the research team will work with fishery managers to simulate relevant future scenarios of interest and assess the potential for yellow perch and alewife to sustain strong recruitments.