ALAN MCGUCKIN, University of Oklahoma, Department of Zoology, 730 Van Vleet Oval, Norman, Oklahoma 73069-0235, USA

GENE GILLILAND, Oklahoma Fisheries Research Laboratory, 500 E. Constellation, Norman, Oklahoma 73072, USA

Preferences of three centrarchid genera were determined for four types of man-made habitat in Thunderbird Reservoir and Arbuckle Reservoir, Oklahoma from May, 1994 through April, 1995. Twelve habitat sites and three control sites were randomly chosen and sampled in each reservoir. Habitat consisted of cedar brush piles, hardwood brush piles, shoreline tree felling, and "pup-tent" shaped structures made of Geoweb, a synthetic plastic material. All structures were placed at depths of less than two meters. Electrofishing surveys conducted at night, twice monthly at all sites in each reservoir revealed that fish densities at man-made habitat sites were significantly higher than at control sites. Cedar brush piles contained the greatest overall densities of all sizes and species of fish collected. Largemouth bass Micropterus salmoides and Kentucky spotted bass M. punctulatus were found to be most dense at cedar piles. Crappie Pomoxis spp. showed no significant differences in habitat selection in this study. Sunfish Lepomis spp. selected cedar brush piles significantly more at both reservoirs. Although habitat type had a significant impact on witnessed fish densities, perhaps the biggest determinant of fish found at these sites was a function of available interstitial space within each differing form of habitat. Brush structures with larger interstitial spaces had higher numbers of legal-sized largemouth bass (>351 mm) and the largest crappie collected. A cost:benefit analysis indicated that addition of brush was a more efficient means of habitat enhancement than were synthetic materials such as Geoweb.