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D.W. Willis

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Little is known about the distribution, movement, and home ranges of bluegills Lepomis macrochirus in lentic environments. Therefore, the objectives of this study were to evaluate the seasonal and diel differences in movement rates, site fidelity, and home range of bluegills in a shallow, natural Great Plains lake. A total of 78 bluegills (200-273 mm total length) were implanted with radio transmitters in March and May 2000. Of these fish, 10 males and 10 females were randomly selected and located every 2 h during one 24-h period each month from April to September 2000. Bluegill movement peaked during midsummer: however, there was little difference in diel movements, suggesting relatively consistent movement throughout...
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Habitat use by bluegill Lepomis macrochirus may be dictated by the avoidance of predators and the availability of prey. Previous work suggests that bluegills large enough to avoid predators will select habitats based on foraging profitability. However, these studies focused on smaller fish (<150 mm standard length) in laboratory experiments or in natural systems with distinct vegetated and open-water habitats. Our objective was to use radio telemetry to determine monthly and diel vegetation selection by larger (>200 mm total length [TL]) bluegills in a shallow (mean depth = 1.2 m), 332-ha, natural lake (Pelican Lake, Nebraska) with both emergent and submergent vegetation distributed throughout. A total of 78 bluegills...
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The gizzard shad (Dorosoma cepedianum) was introduced into 1,955-ha Angostura Reservoir, South Dakota to provide increased prey resources for walleye (Sander vitreus). Linear correlation analysis indicated that following gizzard shad introduction, walleye catch-per-unit-effort and mean length at age have increased over time (r = 0.68 to 0.85, P = 0.02 to 0.001). Walleye stomach contents were collected monthly from April through September, 2004 to determine the extent to which age-0 gizzard shad were being utilized as prey during the growing season. Age-0 gizzard shad were absent from walleye diets from April to mid-July (pre-shad-available period); however, from mid-July through early September (shad-available period),...
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Fisheries managers throughout the Prairie Pothole Region of Minnesota often use semi-permanent and permanent wetland basins to extensively culture walleye Sander vitreus fry. Waterfowl managers have expressed concern over this practice because of the potential influence that fish have on food resources used by waterfowl during development and migration. It is well known that native fathead minnows Pimephales promelas can have detrimental effects on macroinvertebrates, zooplankton, water clarity, epiphyton, and macrophytes in wetlands. Because walleye commonly become piscivorous as soon as mouth gape allows, walleye fry may suppress fathead minnow populations and improve wetland conditions for waterfowl. In this...
Categories: Publication; Types: Citation; Tags: Ecology of Freshwater Fish
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We explored relationships among black bullhead (Ameiurus melas) population characteristics and physicochemical attributes in shallow lakes and quantified relationships between population characteristics of black bullhead and sport fishes. Lake characteristics and fisheries survey data were collected from the Sandhills region of northcentral Nebraska from May through June, 1998 and 1999. Relative abundance of black bullheads was inversely related to proportional stock density (r=-0.672, df=15, P=0.004); however, neither relative weight nor growth was significantly (P ??? 0.20) related to black bullhead relative abundance. Population characteristics of common panfish species such as bluegill (Lepomis macrochirus),...
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