Effects of Macrophytes on Growth of Age-0 Largemouth Bass in Experimental Enclosures

Growth during the summer and fall is critical to the overwinter survival and year-class strength of age-0 Largemouth Bass, yet the aquatic macrophytes that these fish utilize as habitat may often be removed by shoreline property owners. We used experimental enclosures to test the influence of aquatic macrophytes on age-0 Largemouth Bass growth. We placed twelve open-bottomed net pens (9 m²) over substrates with varying (0, 50, and 100%) coverages of aquatic macrophytes in the littoral zone of Chancellor Lake, MI, USA. We stocked the pens with wild, age-0 Largemouth on July 3, August 1, and September 3, 2014 and removed the fish after ~30 d, resulting in three experimental periods. The best-fitting generalized linear mixed model across all periods estimated 30-d growth to be heavier by 0.59 g ± 0.24 (mean ± SD) or ~104% for Largemouth Bass raised in net pens with vegetation present (50% or 100% coverage). Similarly, fish in net pens with vegetation present were 4.9 mm ± 0.15 or ~35% longer than their counterparts. Results from this research can inform efforts to conserve macrophytes through improved understanding of the consequences to Largemouth Bass growth, survival, and year class strength.