Largemouth Bass in Northern Wisconsin: Potential Dietary Interactions With Walleyes

Largemouth bass Micropterus salmoides abundance has increased in many northern Wisconsin lakes over the last decade and this has caused some concern among anglers and biologists because of potential interactions with walleyes Sander vitreus. Previous studies have provided evidence of a negative interaction between the two species occurring through predation of adult largemouth bass on juvenile walleyes and competition for prey.  However, the extent of these interactions remains poorly understood.  Our objective was to determine if diet overlap and predation occurs between walleye and largemouth bass in 2 northern Wisconsin lakes. Diets were collected from adult largemouth bass and walleyes at 2-week intervals during May-October 2012 on Big Sissabagama and Teal lakes in Sawyer County, WI. Whole genomic DNA extraction and sequencing was used to identify the source species for remnant fish tissue in diet samples. Diet analysis suggests that crayfish Orconectes spp. and sunfish Lepomis spp. constitute the major diet items for largemouth bass, whereas yellow perch Perca flavescens and sunfish constitute the major diet items for walleye. Diet overlap between largemouth bass and walleye ranged from high on Big Sissabagama Lake to moderate on Teal Lake. However, no largemouth bass predation on walleye was observed.