Prey selection and diets of bluegill Lepomis macrochirus with differing population characteristics in two Nebraska natural lakes

Fisheries Management and Ecology (Impact Factor: 1.76). 01/2003; 10(1):31 - 40. DOI: 10.1046/j.1365-2400.2003.00323.x


Abstract  Environmental prey samples and stomach contents of bluegill Lepomis macrochirus (Rafinesque) were collected in spring and summer 2000 from two Nebraska Sandhill lakes. Watts Lake contained a low-density bluegill population, whereas Cozad Lake contained a high-density bluegill population. Bluegill diets from both lakes were compared to determine if bluegill prey preference differed between the two populations. The highest median per cent (by calories) of zooplankton in the diet was 1.3%; the remainder was macroinvertebrates. Watts Lake bluegills preferred (based on Manly's alpha) amphipods in spring and chironomids in summer. Cozad Lake bluegills did not show a strong preference (compared with Watts Lake) for any macroinvertebrates, but still utilized amphipods and chironomids during both seasons. Larger bluegills in Watts Lake preferred chironomids in summer, but Cozad Lake bluegills did not exhibit this relationship. The higher density Cozad Lake bluegill population appeared to be more opportunistic than the lower density Watts Lake population, but both preferred macroinvertebrates.

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    • "In contrast to northern natural lakes where adult bluegill inhabit pelagic areas and forage extensively on zooplankton (Werner et al., 1983; Werner & Hall, 1988), several studies of bluegill diet and feeding behavior in reservoirs and natural lakes in the lower Midwest and southeastern United States have found that bluegills rely primarily on littoral macroinvertebrates independent of size or population density (Schramm & Jirka, 1989; Dewey et al., 1997; Olson et al., 2003). These differences may be caused by changes in the relative profitability of benthic versus pelagic resources due to environmental differences between lakes such as in water clarity, littoral habitat, and/or nutrient levels and should be investigated further. "
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