Comparison of Summer Gill Netting and Trap Netting to Fall Trap Netting forSampling Crappie Populations in Minnesota Lakes

摘要

Summer (June through August) gill netting and trap netting for sampling blackcrappie Pomoxis nigromaculatus and white crappie P. annularis was compared to fall trap netting in Minnesota lakes. No clear advantage for evaluating abundance and size structure of crappie populations was evident in 40 lakes netted during both summer and fall. Catch-per-unit-effort (CPUE) of black crappie in gill nets was significantly lower than CPUE in trap nets for 2,811 surveys from the statewide data base, but white crappie CPUE in gill nets was significantly higher than CPUE in trap nets. Significantly smaller individuals of both species were captured in gill nets. Black crappie CPUE in gill nets was more precise, while black crappie CPUE in trap nets was better correlated with angler catch per hour and harvest per hectare. White crappie CPUE in gill nets was also more precise, but neither CPUE in gill nets nor in trap nets was significantly correlated with angler catch indices. A negative correlation existed between net catch length frequencies and angler harvest length frequencies.