Ecology of fish communities in Nebraska Sandhill lakes

Fish populations recruitment, growth, and mortality are regulated by biotic and abiotic factors. The first study objective was to evaluate the influence of biotic and abiotic characteristics on the fish communities in Nebraska Sandhill lakes. I selected 30 lakes and measured fish community characteristics, invertebrate populations, and habitat in all lakes. I also evaluated angler impact by using creel data and studied populations in three lakes that were closed to fishing. Finally, I used radio telemetry to determine habitat selection of bluegills Lepomis macrochirus in one Sandhill lake.; There was little evidence of density-dependent growth for any fish species in these Sandhill lakes. For panfish (bluegill and yellow perch Perca flavescens), growth and condition were typically high among all lakes. However, northern pike Esox lucius exhibited relatively low condition when compared to other fish species. Quality bluegill and yellow perch populations were influenced by their environment; however, predation by largemouth bass Micropterus salmoides and northern pike appeared to be more influential.; Nebraska Sandhill lakes presumably have limited exploitation. Creel survey data for Pelican and Hackberry lakes (Cherry County) suggested that bluegill exploitation was <10%. However, one unexploited yellow perch population in a privately owned water body exhibited high condition, fast growth, and was composed of a high proportion of large fish. In contrast, two other unexploited yellow perch populations exhibited population structure similar to exploited populations, suggesting that exploitation is not the only factor contributing to the structure and dynamics of these populations. A simulated 200-mm bluegill minimum length limit provided limited benefit if the management objective was to increase abundance of larger (e.g., ≥200 mm) bluegills. However, anglers interviewed were in favor of restrictive regulations. These bluegill populations exhibited a slight increase in size structure, but a reduction in yield and number of fish harvested with the simulated length limit.; Larger bluegills generally selected for emergent vegetation across spring, summer, and fall. Because these fish were sufficiently large to avoid predation, the selection for vegetation may be related to foraging. In addition, invertebrate densities were most likely sufficiently high enough for bluegill to prey effectively in vegetated areas.