Assessing Fish Communities and Habitat Dynamics at the North Platte River-Lake Mcconaughy Interface: Implications for Conservation and Management

The river-reservoir interface (RRI) provides dynamic habitat heterogeneity that influences fish communities within the reservoir and the tributary upstream. However, little is known about the North Platte River-Lake McConaughy interface. Thus, the objectives of this research were to: 1) describe fish assemblages in the North Platte River and relate their temporal differences to water quality and physical habitat parameters; and 2) compare young fish communities collected with different gears in the upper reservoir. Twenty-nine species were collected across four habitat types in the North Platte River above Lake McConaughy. Main and side channel habitats were more consistently available throughout the summer. Backwater habitats declined in abundance, and back eddies disappeared. Species richness and Shannon’s diversity were highest in backwaters. Fish communities were somewhat similar between the habitat types, but some species were more or less abundant in some habitats. Water quality did not differ between habitat types. However, discharge and water temperature appeared to influence community composition. In upper Lake McConaughy, I captured 21 taxa across four sampling gears. Fewer species were captured with the gears used in the earlier time period compared to the gears used later time period. Species richness, Shannon’s diversity, and relative abundance were highest for seines and lowest for tow nets. Boat-mounted electrofishing appeared to be the most efficient gear. Similarities were noted in fish communities between the two time periods, but abundance of individual species varied between time periods. This study provides updated and new information on fish communities in the North Platte River-Lake McConaughy system. Selecting the sampling gear or gears that best meet sampling objectives is important for understanding fish communities in RRIs. With such sampling information, fisheries managers may be able to identify water management strategies that provide habitats for fish communities in unique ecotones such as the RRI