Effects of Highly Fluctuating Flows on Nest Success of Redbreast Sunfish in the Tallapoosa River, Alabama

Robert O. Andress, Kevin Kleiner and Elise R. Irwin
Alabama Cooperative Fish and Wildlife Research Unit, Auburn University, 103 Swingle Hall, Auburn University, Auburn, Alabama 36849, USA. 334-844-9318; Fax 334-844-9208; andrer1@mail.auburn.edu

To quantify spawning success, 140 redbreast sunfish (Lepomis auritus) nests were observed from late May through June 1999, in the Tallapoosa River, Alabama, 22 km below R.L. Harris Dam, a peaking hydropower facility. Underwater observations using snorkeling techniques were made at least three times a week on redbreast sunfish nests to examine survival of early life history stages in relation to flow regime. Nests were subject to pulse flows from 6,000 cfs to greater than 10,000 cfs daily. Our data suggest that nest persistence is dependent upon developmental stage of eggs and larvae and position of the nest. Eggs and yolk sac larvae were more likely to survive high flow events than swim-up fry. In addition, nests located close to cover were less likely to be destroyed than nests positioned away from structure. Only eight nests of the 140 yielded swim-up fry during observation. Provision of stable flow periods would likely increase recruitment of centrarchids in this system.