Introgressive hybridization between native and introduced species is a growing conservation concern. For native cutthroat trout and introduced rainbow trout in western North America, this process is thought to lead to the formation of hybrid swarms and the loss of monophyletic evolutionary lineages. Previous studies of this phenomenon, however, indicated that hybrid swarms were rare except when...

—Cutthroat trout Oncorhynchus clarkii frequently are displaced by nonnative brook trout Salvelinus fontinalis, but the ecological mechanisms of displacement are not understood. Competition for food and predation between greenback cutthroat trout O. c. stomias and brook trout were investigated in montane streams of Colorado. A replicated field study was used to describe the population density, d...

Background Many fish species have been introduced in wild ecosystems around the world to provide food or leisure, deliberately or from farm escapes. Some of those introductions have had large ecological effects. The north American native rainbow trout (Oncorhynchus mykiss Walbaum, 1792) is one of the most widely farmed fish species in the world. It was first introduced in Spain in the late 19th...

I used multiple approaches to study brook trout invasions in mountainous streams of Idaho and Montana, USA. After studying marked fish in experimental reaches and fish distributions throughout a drainage, I concluded that larger brook trout (95mm) moved more than smaller ones and were probably responsible for most dispersal leading to invasion. Contrary to earlier hypotheses, poor swimming abil...

Sympatric populations occur in many freshwater fish species; such populations are typically detected through morphological distinctions that are often coupled to food niche and genetic separations. In salmonids, trophic and genetically separate sympatric populations have been reported in landlocked Arctic char, whitefish and brown trout. In Arctic char and brown trout rare cases of sympatric, g...

—Invasions of nonnative species are a leading cause of the loss of populations of cutthroat trout Oncorhynchus clarki in the western United States, but effective control of invasions of species such as brook trout Salvelinus fontinalis are expensive, labor intensive, and not species specific. Because salmonids respond to chemical cues, we hypothesized that pheromonal attraction could be exploit...

Dams and water diversions can dramatically alter the hydraulic habitats of stream ecosystems. Predicting how water depth and velocity respond to flow alteration is possible using hydraulic models, such as Physical Habitat Simulation (PHABSIM); however, such models are expensive to implement and typically describe only a short length of stream (10m). If science is to keep pace with development, ...

—This work summarizes pre-1998 studies of population abundance of stream resident redband trout Oncorhynchus mykiss ssp. in Oregon, and compares basin-level surveys of habitat and fish populations in streams of two ecoregions. Interquartile values of density and biomass were used to develop benchmarks of high, moderate, and low abundance. Comparison among Crooked River streams (Blue Mountain ec...

—Theoretical models and empirical evidence suggest that the invasion of nonnative species in freshwaters is facilitated through the interaction of three factors: habitat quality, biotic resistance, and connectivity. We measured variables that represented each factor to determine which were associated with the occurrence of nonnative brook trout Salvelinus fontinalis in Panther Creek, a tributar...