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Anthropogenic changes to the Pyramid Lake–Truckee River ecosystem in Nevada are suspected to have altered the predator–prey balance between American white pelican Pelecanus erythrorhynchos and Cui‐ui Chasmistes cujus. We estimated the loss of the adult Cui‐ui population to pelican predation over a 13‐year period by netting and tagging Cui‐uis as they aggregated at the mouth of the Truckee River prior to their spawning migration into the Truckee River. Cui‐ui access to the Truckee River typically required traversing a shallow delta (a foraging advantage for these American white pelicans). Dams and greater frequency of low stream flows also contributed to American white pelican foraging success. We used tag recoveries from Pyramid Lake's nesting colony of American white pelicans along with an experiment to estimate the chance of tag recovery within the colony to calculate the number of tagged fish taken by American white pelicans. We also used numbered tags to test whether there was a size preference for Cui‐uis taken. Our results showed that the primary source of adult Cui‐ui mortality was from American white pelican predation in the Truckee River. Within a 13‐year period American white pelicans had taken 90% of the tags deployed during the first 7 years of the interval. There was no preference for the size of Cui‐uis taken. A better understanding of the effects of heavy cropping by American white pelicans on Cui‐ui population dynamics is still needed.Received March 26, 2013; accepted October 8, 2013Published online January 24, 2014

Non-native fish generally cause native fish decline, and once non-natives are established, control or elimination is usually problematic. Because non-native fish colonization has been greatest in anthropogenically altered habitats, restoring habitat similar to predisturbance conditions may offer a viable means of non-native fish control. In this investigation we identified habitats favoring native over non-native fish in a Mojave Desert oasis (Ash Meadows) and used this information to restore one of its major warm water spring systems (Kings Pool Spring). Prior to restoration, native fishes predominated in warm water (25-32°C) stream and spring-pool habitat, whereas non-natives predominated in cool water (•23°C) spring-pool and marsh/ slack water habitat. Native Amargosa pupfish (Cyprinodon nevadensis) and Ash Meadows speckled dace (Rhinichthys osculus nevadensis) inhabited significantly faster mean water column velocities (MWCV) and greater total depth (TD) than non-native Sailfin molly (Poecilia latipinna) and Mosquitofish (Gambusia affinis) in warm water stream habitat, and Ash Meadows speckled dace inhabited significantly faster water than non-natives in cool water stream habitat. Modification of the outflow of Kings Pool Spring from marsh to warm water stream, with MWCV, TD, and temperature favoring native fish, changed the fish composition from predominantly nonnative Sailfin molly and Mosquitofish to predominantly Ash Meadows pupfish. This result supports the hypothesis that restoring spring systems to a semblance of predisturbance conditions would promote recolonization of native fishes and deter non-native fish invasion and proliferation.