Entrainment of ichthyoplankton by a warmwater hydroelectric facility

The authors examined entrainment of ichthyoplankton associated with hydropowergeneration in 1988 and 1989 at the Pensacola Dam hydroelectric facility on Grand Lake innortheastern Oklahoma. To provide a basis for evaluating the effects of entrainment on the fishassemblage, they also estimated the total abundance of fish eggs and larvae in the top 10 m ofthe reservoir. Entrainment totalled about 10 million larval fish in 1988 and almost 100 million in1989. Only nine taxa of larval fish were entrained during the study. Entrained eggs were almostexclusively those of freshwater drum Aplodinotus grunniens. Although estimates of entrainmentwere large, they were generally low compared with the estimates of total abundance ofichthyoplankton in Grand Lake

Recovery of a warmwater fish assemblage after the initiation of a minimum-flow release downstream from a hydroelectric dam

Artificial fluctuations in streamflow caused by hydroelectric power dams can degradefish habitat and reduce the abundance and diversity of riverine fish faunas, Increased minimumwater releases and reduced fluctuations in discharge may mitigate these effects. In this study, wecompared shoreline fish abundance and diversity before and after an enhanced flow regime wasimplemented on the Tallapoosa River (Alabama) downstream of a hydroelectric dam. Before theminimum-how regime, only eight species of fish were collected 3 km downstream from the dam,and all were classified as macrohabitat generalists. After the minimum flow was initiated, speciesrichness 3 km below the dam more than doubled, and over half of the species collected wereclassified as fluvial specialists. Fish community response to the enhanced flow was not as greatat a site 37 km downstream from the dam, where species richness was similar between the twoperiods. However, more species classified as fluvial specialists were collected after the minimumflow regime than before enhanced flows at this site. Additionally, relative abundance of speciesclassified as fluvial specialists increased from less than 40% of fish collected before enhancedflows to over 80% after minimum flows began. Our results suggest that the enhanced flow regimeprovided conditions supporting a relatively abundant and diverse fish assemblage more reflectiveof a riverine system