Predators of White Perch at Branched Oak and Pawnee Reservoirs
Sedimentation and erosion have significantly altered the habitat of Branched Oak Lake, resulting in loss of usable littoral habitat and a predominance of turbid open-water areas. This loss of critical near-shore habitat, coupled with the introduction of the white perch, has changed the population dynamics within the fish community. White perch numbers have increased precipitously over the last decade resulting in a stunted white perch population in Branched Oak Lake. This unchecked white perch population is suspected of severely limiting recruitment of sport fishes such as walleye. Control of this stunted white perch population is thus desired. Chemical renovation of Branched Oak Lake has been considered; however, logistical difficulties have precluded this action. Research was initiated to assess the feasibility of biological control of white perch via predation.
GoalsThe purpose of this project was to quantify food habits of adult white crappie, walleye, channel catfish, flathead catfish, hybrid striped bass and white bass to determine which, if any, of these fishes prey on white perch. Like Branched Oak Lake, Pawnee Lake historically supported an active and diverse fishery, and has experienced similar habitat alterations and accidental introduction of white perch. However, unlike Branched Oak Lake, the Pawnee Lake white perch population has not yet stunted. Thus, an opportunity existed to document predators of white perch in populations with two different size structures, allowing for predictions of likely changes in food habits of predators with purposeful changes in the targeted prey (white perch) population. This project provided information about food habits of predatory fishes that could allow for refinement of the current management program for white perch populations in Nebraska reservoirs.
This project is complete with results compiled into a master's thesis. Primary research finding: The current predatory population in Branched Oak Lake is unlikely to alter (via predation) the stunted status of the white perch population. Rather, the cropping off of larger white perch via predation in Branched Oak Lake is reinforcing the stunted status of the white perch population.