Managing Macrophytes to Improve Fish Growth: A Multi-lake Experiment

Abstract

Macrophyte harvesting often has been suggested as a way to improve fish growth and size structure in lakes with high densities of submergent macrophytes and stunted fish populations. However, previous experimental tests have provided no clear consensus on whether the technique works for management. We conducted a series of whole‐lake manipulations to test the effects of macrophyte removal on growth of bluegill and largemouth bass. We selected four lakes in southern and central Wisconsin for experimental manipulation and nine others for controls. In August 1994, we removed macrophytes from approximately 20% of the littoral zone by cutting a series of evenly spaced, deep channels throughout each treatment lake. In the first year after manipulation, we observed substantially increased growth rates of some age classes of both bluegill and largemouth bass in treatment lakes relative to controls. Growth rates of other age classes were less responsive to manipulation. We observed increased bluegill and largemouth bass growth despite rapid regrowth of macrophytes in our treatment lakes. By May 1996, fewer than 25% of the channels remained. Our results suggest that harvesting macrophytes in a series of deep channels may be a valuable tool for integrated management of fish and macrophytes.

Structural Complexity Influences Littoral Coarse Woody Habitat Selection by Juvenile Muskellunge

“…Piscivores often use complex habitats for foraging and ambush opportunities (Ekl€ ov 1997;Olson et al 1998;Sass et al 2006a). In addition to Muskellunge, other fishes are also attracted to CWH and their abundance may increase with CWH structural complexity (Newbrey et al 2005).…”

Diets of Micropterus Salmoides Lac. And Esox Lucius L. In Lake Trasimeno (Umbria, Italy) and Their Diet Overlap.

“…Fish and shrimps seemed to be the food alternatives of pike and largemouth bass based on their abundance and vulnerability which vary seasonally. M. salmoides are less efficient foragers than E. lucius in areas that are thick with hydrophytes that provide refuge for the fish prey (OLSON et al, 1998) and its foraging success has been shown to decrease with the increasing abundance of submerged vegetation (GODINHO et al, 1997). In manipulative experiments in a Texas reservoir BETTOLLI et al (1992) have found that before aquatic vegetation removal the diet of largemouth bass was made mainly of insects, amphipods and P. antennarius, whereas after the removal of the vegetation piscivory increased significantly.…”

Spatial and temporal occurrence of hypoxia influences fish habitat quality in denseHydrilla verticillata

“…The open water area adjacent to dense hydrilla habitat at Sandmine Lake was approximately 1 ha, and was not large enough to influence DO on dense hydrilla bed edges or interior. Increasing ecotonal habitat via channelization can promote macroinvertebrate and fish communities with increased hydrilla branching and fish foraging, provide alternative fish habitat during hypoxic periods, and benefit recreational boaters for navigation (Lillie & Budd 1992;Trebitz & Nibbelink 1996;Olson et al 1998). With recent advances in GPS and deep-water mechanical removal of dense macrophytes, longer term control in channels may now be possible (Haller & Jones 2012).…”