Spatio-temporal dynamics of yellow perch-alewife interactions in Lake Michigan: Implications for yellow perch recruitment (Perca flavascens, Alosa pseudoharengus)

Yellow perch recruitment in Lake Michigan has been extremely low since the early 1990s, prompting intensive research efforts to determine the mechanisms regulating year-class strength. Much is unknown about the early-life history spatial and temporal distribution of the species, due in part to inefficiencies of traditional sampling gear, which do not capture yellow perch larvae >8mm. Additionally, the potential influence of predation, particularly by adult alewives, on early life stage survival of yellow perch has not been determined. This study evaluated the ability of side-looking hydroacoustics to detect and estimate densities of larval yellow perch. Also, the dynamics of spatial and temporal overlap between larval yellow perch and their potential predators in southwestern Lake Michigan from 1999–2001 were explored. Hydroacoustics proved to be highly efficient at detecting larval yellow perch with swim bladders, but field density estimates were highly influenced by water surface conditions. The spatial and temporal overlap of larval yellow perch and potential predator distributions varied greatly among years, with highest predation likely occurring in offshore waters in 2000. This study provides insight into new methods for sampling larval yellow perch, and shows that predation on larval yellow perch may be a factor influencing yellow perch year-class strength.