MELISSA SMITH AND ELISE IRWIN, Alabama Cooperative Fish and Wildlife Research Unit, Auburn University, 103 Swingle Hall, Alabama 36849, USA

Three gears were evaluated for collecting flathead catfish Pylodictis olivaris and channel catfish Ictalurus punctatus in Alabama; small and large hoop nets, electrofishing grids, and a catfish "rigged" electrofishing boat. Catfishes were collected monthly from four sites on the Tallapoosa River, May-September 1996. Type of gear and time of day introduced bias in terms of both species and size of fish captured. Small and large hoop nets selected for large flathead catfish (>350 mm). Electrofishing grids set at night targeted small channel catfish (8-200 mm), but captured only two flathead catfish. Daytime electrofishing grids were not effective for catching catfishes. The electrofishing boat captured both species and a larger size range of catfish (20-950 mm) than the other two gears. However, catfish > 550 mm were rarely captured. Electrofishing technique was also important, whereas, catch-per-unit-effort usually doubled when a "chase boat" was employed. Gear biases are likely caused by temporal and spatial variation in habitats sampled and size selectivity. For example, electrofishing grids sample shallow water and are effective only at night for small individuals. Because of differences in species and size of catfishes collected and the habitats targeted by each gear type, all three gears are needed to sample catfish populations effectively.