Smallmouth Bass Diet Analysis in a Warmwater Central Wisconsin Stream
Colin Staley (Not Pictured)
Simon Bienvenue (Not Pictured) Fisheries and Aquatic Sciences
Mason Scheffer (Not Pictured)
Fisheries and Aquatic Sciences
Fisheries and Aquatic Sciences
Smallmouth bass Micropterus dolomieu (SMB) are an important opportunistic top predator and highly sought after gamefish in a variety of warm and cool water systems. The number of suitable SMB streams is expected to increase as water temperatures rise with climate change; however, limited information exists regarding important SMB diet items in smaller streams. Our objectives were to determine if certain prey were more common in SMB diets and if prey differed based on SMB total length. In fall 2022, 2023, 2024, and 2025, we sampled the Pigeon River in central Wisconsin. We used backpack electrofishing to sample all fish species at two distinct sites, totaling 700 yards each year. All fish (n = 1545) were identified and measured for total length. If SMB were >130 mm, a gastric lavage was conducted (n = 136). We calculated an Index of Relative Importance (IRI) and a reduced IRI (rIRI). Results indicate that crayfish, fish (including remnants), and insects all occur with high frequency in SMB diets. However, based on the IRI and rIRI, SMB <200 mm feed heavily on aquatic insects, specifically ephemeropterans and trichopterans, while SMB >200 mm feed heavily on crayfish. Our results contribute to baseline data on SMB in small streams including important diet items and available prey, aiding in future management as small streams respond to climate change impacts.
Advisors: Joshua Raabe, Ph.D. Jeffrey Dimick, Ph.D.
Subject Area: Fisheries and Water
Type: Poster
85
UW-Stevens Point College of Natural Resources
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