Emigration of Fish from Two South Carolina Cooling Reservoirs

Abstract

We assessed fish escapement from two South Carolina reservoirs, Par Pond and L Lake, from spring 2002 through summer 2003. Escapement was greatest in the spring and early summer, with lake chubsucker Erimyzon sucetta dominating the escapement catch in early spring and several sunfishes Lepomis spp. dominating in late spring and early summer. Most of the escaping centrarchids were bluegill L. macrochirus, warmouth L. gulosus, and redbreast sunfish L. auritus in L Lake and warmouths, bluegills, dollar sunfish L. marginatus, and spotted sunfish L. punctatus in Par Pond. Escapement was enhanced by high reservoir water levels and surface discharge over the spillway. Escapement declined during periods of hypolimnetic release from bottom discharge gates. Location of the Par Pond discharge structure in the littoral zone rather than the pelagic zone as in L Lake contributed to greater escapement of littoral species in Par Pond. Species composition in the escapement catches and reservoirs was not significantly correlated. Relatively low escapement from L Lake and Par Pond compared with that in other reservoirs may have been related to the configuration of the discharge structures, low water levels during 2002, fish habitat preferences, species composition and abundance in the reservoirs, and low rates of discharge.