Effects of biotic and abiotic factors on the distribution of trout and salmon along a longitudinal stream gradient

Abstract

SynopsisWe examined the influence of biotic and abiotic factors on the distribution, abundance, and condition of salmonid fishes along a stream gradient. We observed a longitudinal change in fish distribution with native cutthroat trout, Oncorhynchus clarki utah, and introduced brown trout, Salmo trutta, demonstrating a distinct pattern of allopatry. Cutthroat trout dominated high elevation reaches, while reaches at lower elevations were dominated by brown trout. A transition zone between these populations was associated with lower total trout abundance, consistent changes in temperature and discharge, and differences in dietary preference. Variation in cutthroat trout abundance was best explained by a model including the abundance of brown trout and diel temperature, whereas variation in brown trout abundance was best explained by a model including the abundance of cutthroat trout and discharge. These results suggest the potential for condition-mediated competition between the two species. The results from our study can aid biologists in prioritizing conservation activities and in developing robust management strategies for cutthroat trout.

Predation on native sculpin by exotic brown trout exceeds that by native cutthroat trout within a mountain watershed (Logan, UT, USA)

“…Diet samples were collected as part of other research (de la Hoz Franco & Budy 2005;McHugh et al 2008) and/or were a component of annual surveys occurring from July to November, during the years 2001-2009. Diet samples were collected as part of other research (de la Hoz Franco & Budy 2005;McHugh et al 2008) and/or were a component of annual surveys occurring from July to November, during the years 2001-2009.…”

“…Previous research suggests that brown trout in the Logan River consume more fish than native Bonneville cutthroat trout of a similar size (de la Hoz Franco & Budy 2005;McHugh et al 2008), which may contribute to the species' competitive advantage over cutthroat trout. in the Logan River.…”

Invasion of north European streams by brook trout: hostile takeover or pre-adapted habitat niche segregation?

“…Flebbe 1994;Rahel and Nibbelink 1999;Korsu et al 2007). Thus, distribution patterns of salmonids are regulated by processes effective at multiple spatial scales, eventually shaping the zonation pattern through the combined effect of speciesspecific niche adaptations and environmentally driven ecological performances (De Staso and Rahel 1994;Taniguchi and Nakano 2000;De la Hoz Franco and Budy 2005). Nevertheless, the relative roles of competitive interactions and adaptive habitat segregation to salmonid invasions remain unclear in most cases, making invasions look idiosyncratic and largely unpredictable (Korsu et al 2008;Fausch 2008).…”

Coeur d'Alene Tribe Fisheries Program : Implementation of Fisheries Enhancement Opportunities on the Coeur d’Alene Reservation : 2007 Annual Report.

“…Cutthroat trout have been found to remain in tributary habitats and to display minimal displacement to downriver reaches during the summer if suitable foraging habitat was readily available nearby (Schrank and Rahel 2006). Given the consistently higher densities of cutthroat trout in tributary than in mainstem habitats, the mid-summer differences in rearing temperatures between tributary and mainstem reaches likely explain in part the distributional patterns of cutthroat trout observed during our population surveys (Dunham et al 1999;Paul and Post 2001;Sloat et al 2001;de la Hoz Franco and Budy 2005).…”