Prevalence and Timing of Piscivory within of Age-0 Largemouth Bass Cohorts in Wisconsin Lakes

Largemouth bass Micropterus salmoides advance through a series of dietary shifts during early life, eventually switching to piscivory. The onset of piscivory is important to the survival and growth of age-0 largemouth bass and affects the number of fish that will eventually recruit to the fishery. Recent increases in largemouth bass abundance in Wisconsin lakes have prompted renewed interest in the factors regulating largemouth bass recruitment. The onset of piscivory has been poorly studied in largemouth bass populations at the northern edge of their native range. A better understanding of the prevalence and onset of piscivory in Wisconsin largemouth bass populations would allow fishery managers to better understand increases in largemouth bass population dynamics.  The objectives of our study were to 1) determine if piscivory was evident in age-0 largemouth bass collected from Wisconsin Lakes and 2) determine if the extent of piscivory was related to bass length or latitude. Currently, we have observed little evidence of piscivory in three of the four lakes; bass diets have largely consisted of invertebrates of various orders including: Amphipoda, Cladocera, Copepoda, and Hemiptera.  In one lake, age-0 largemouth bass appeared to have switched to piscivory at an average length of 73 mm.