How Depth and Interstice Size of Artificial Structures Influence Fish Attraction

Adding artificial structures to lakes has been common, but guidelines for ensuring the utility of these additions are lacking. We used pop nets to evaluate fish use of artificial structures with two interstice sizes (40 and 350 mm) placed at two depths (3.0 and 4.5 m) in an Ohio reservoir. Bluegills Lepomis macrochirus preferred 40-mm interstices at 3.0 m. Pumpkinseeds Lepomis gibbosus and bullheads Ictalurus spp. also preferred denser structures but at the 4.5-m depth. White crappies Pomoxis annularis showed no preference, and their use of structures declined as summer progressed, probably because they moved to water deeper than 4.5 m. Catches of gizzard shad Dorosoma cepedianum were greatest from 4.5-m-deep structures, but no interstice size preference was evident. We found no relation between use of structures and a narrow range of physicochemical variables. Fisheries managers should use dense materials in structures to attract sunfish and bullheads. They can expect greater use of shallow structures by bluegills, whereas bullheads, gizzard shad, pumpkinseeds, and white crappies will prefer deeper structures. Adding structures to waters dominated by small centrarchids is not warranted, because substantial increases in angler harvest will not occur and structures may further decrease centrarchid mortality and growth.