Effects of Vegetation Removal on Bluegill and Largemouth Bass in Two Minnesota Lakes

Abstract

Abstract Abundance and growth of bluegill Lepomis macrochirus, diet and growth of largemouth bass Micropterus salmoides, and abundance of age-0 largemouth bass were evaluated in two treatment and three reference lakes in Minnesota to assess the effects of whole-lake herbicide treatments. Lakes were evaluated 1 year prior (1993), during (1994), and after (1995) treatment. In reference lakes, vegetation, fish growth, abundance, and diet remained relatively unchanged throughout the study. Herbicide applications in May 1994 decreased the percentage of sampling stations with vascular vegetation from 100% to 33% in Parkers Lake and 63% in Zumbra Lake between Aug 1993 and 1994. Vegetation returned to some areas of Parkers Lake in 1995 (77%) but continued to decline in Zumbra Lake (43%). Purse-seine catch per effort (CPE) of small bluegill (60–100 mm) decreased following treatment but returned to pretreatment levels the following year, whereas CPE of large bluegill (>100 mm) increased in 1994 in trap nets and rem...