| Summary: | 2014 Spring. Includes bibliographical references. The 20th century was a period of rapid reservoir construction in the western United States. Initially, many of these reservoirs hosted productive recreational fisheries for introduced salmonids, but then waned from oligotrophication, dam operations, and the effects of introduced opossum shrimp Mysis diluviana. Managers have sought alternative fish species that could withstand these trophic constraints. In 1990 the state of Colorado introduced Arctic Char Salvelinus alpinus into Dillon Reservoir hoping they would prey on Mysis and produce a valuable "boutique fishery". My study investigated the outcomes of this introduction. I found that the introduction resulted in a reproducing population, creating one of the only public fisheries for Arctic Char in the lower 48 states of the USA, and the southernmost population in the world. Arctic Char diet was composed primarily of Mysis shrimp, and their growth was among the fastest of lacustrine populations worldwide. While bioenergetics simulations showed that approximately 3-6 times as many Arctic Char would need to be stocked annually to effectively control Mysis shrimp, Arctic Char did channel energy formerly sequestered in Mysis into desirable recreational fish biomass. Despite this desirable ecosystem service, the stocking program is paradoxical. In an era when nonnative species comprise a primary threat to aquatic biodiversity, condoning new introductions is concerning. However, in many human-dominated environments such as reservoirs, exotic fishes already comprise the majority of species. Fishery managers are left with the problem of choosing relatively innocuous strategies that can still provide recreational benefits in systems plagued by a variety of anthropogenic stressors.
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