Geology topics

Research about Logan River

Source-linked reports with geographic coverage including Logan River.

6 recordsLinked to original sources

USGS2022

High densities of conspecifics buffer native fish from negative interactions with an ecologically similar invasive

Invasive species are a leading cause for native species declines, but it remains unclear whether maintenance of high native densities influence native persistence in freshwater systems. We designed complementary laboratory and field experiments to test whether high native cutthroat trout (Oncorhynchus clarkii) densities affect competition with invasive brown trout (Salmo trutta). We manipulated density of native cutthroat trout while holding brown trout density constant. Interspecific aggressive interactions towards native cutthroat trout were 66% fewer in the highest cutthroat trout density treatment compared to the lowest density treatment. At high densities of conspecifics, cutthroat trout, sympatric with brown trout, lost 33-81% less weight and demonstrated 1.5 times greater survival in both experiments than at low conspecific densities. Cutthroat trout held at low densities in laboratory experiments experienced greater stress-related disease virulence and negative effects of harassment, apparently owing to more frequent aggressive interactions with brown trout. These results support the hypothesis that reduced per capita effects of invaders on native fish at high densities buffers native species from negative effects of invaders, reducing the potential for invasive fish to displace high density native fish populations.

Utah↗

USGS2018

Modeling the fish community population dynamics and forecasting the eradication success of an exotic fish from an alpine stream

Management actions aimed at eradicating exotic fish species from riverine ecosystems can be better informed by forecasting abilities of mechanistic models. We illustrate this point with an example of the Logan River, Utah, originally populated with endemic cutthroat trout ( Oncorhynchus clarkii utah ), which compete with exotic brown trout ( Salmo trutta ). The coexistence equilibrium was disrupted by a large scale, experimental removal of the exotic species in 2009–2011 (on average, 8.2% of the stock each year), followed by an increase in the density of the native species. We built a spatially-explicit, reaction-diffusion model encompassing four key processes: population growth in heterogeneous habitat, competition, dispersal, and a management action. We calibrated the model with detailed long-term monitoring data (2001–2016) collected along the 35.4-km long river main channel. Our model, although simple, did a remarkable job reproducing the system steady state prior to the management action. Insights gained from the model independent predictions are consistent with available knowledge and indicate that the exotic species is more competitive; however, the native species still occupies more favorable habitat upstream. Dynamic runs of the model also recreated the observed increase of the native species following the management action. The model can simulate two possible distinct long-term outcomes: recovery or eradication of the exotic species. The processing of available knowledge using Bayesian methods allowed us to conclude that the chance for eradication of the invader was low at the beginning of the experimental removal (0.7% in 2009) and increased (20.5% in 2016) by using more recent monitoring data. We show that accessible mathematical and numerical tools can provide highly informative insights for managers (e.g., outcome of their conservation actions), identify knowledge gaps, and provide testable theory for researchers.

Utah↗

USGS2016

Assessing conditions influencing the longitudinal distribution of exotic brown trout (Salmo trutta) in a mountain stream: a spatially-explicit modeling approach

Trout species often segregate along elevational gradients, yet the mechanisms driving this pattern are not fully understood. On the Logan River, Utah, USA, exotic brown trout ( Salmo trutta ) dominate at low elevations but are near-absent from high elevations with native Bonneville cutthroat trout ( Onchorhynchus clarkii utah ). We used a spatially-explicit Bayesian modeling approach to evaluate how abiotic conditions (describing mechanisms related to temperature and physical habitat) as well as propagule pressure explained the distribution of brown trout in this system. Many covariates strongly explained redd abundance based on model performance and coefficient strength, including average annual temperature, average summer temperature, gravel availability, distance from a concentrated stocking area, and anchor ice-impeded distance from a concentrated stocking area. In contrast, covariates that exhibited low performance in models and/or a weak relationship to redd abundance included reach-average water depth, stocking intensity to the reach, average winter temperature, and number of days with anchor ice. Even if climate change creates more suitable summer temperature conditions for brown trout at high elevations, our findings suggest their success may be limited by other conditions. The potential role of anchor ice in limiting movement upstream is compelling considering evidence suggesting anchor ice prevalence on the Logan River has decreased significantly over the last several decades, likely in response to climatic changes. Further experimental and field research is needed to explore the role of anchor ice, spawning gravel availability, and locations of historical stocking in structuring brown trout distributions on the Logan River and elsewhere.

Utah↗

USGS2014

Demographic changes following mechanical removal of exotic brown trout in an Intermountain West (USA), high-elevation stream

Exotic species present a great threat to native fish conservation; however, eradicating exotics is expensive and often impractical. Mechanical removal can be ineffective for eradication, but nonetheless may increase management effectiveness by identifying portions of a watershed that are strong sources of exotics. We used mechanical removal to understand processes driving exotic brown trout ( Salmo trutta ) populations in the Logan River, Utah. Our goals were to: (i) evaluate the demographic response of brown trout to mechanical removal, (ii) identify sources of brown trout recruitment at a watershed scale and (iii) evaluate whether mechanical removal can reduce brown trout densities. We removed brown trout from 2 km of the Logan River (4174 fish), and 5.6 km of Right Hand Fork (RHF, 15,245 fish), a low-elevation tributary, using single-pass electrofishing. We compared fish abundance and size distributions prior to, and after 2 years of mechanical removal. In the Logan River, immigration to the removal reach and high natural variability in fish abundances limited the response to mechanical removal. In contrast, mechanical removal in RHF resulted in a strong recruitment pulse, shifting the size distribution towards smaller fish. These results suggest that, before removal, density-dependent mortality or emigration of juvenile fish stabilised adult populations and may have provided a source of juveniles to the main stem. Overall, in sites demonstrating strong density-dependent population regulation, or near sources of exotics, short-term mechanical removal has limited effects on brown trout populations but may help identify factors governing populations and inform large-scale management of exotic species.

Utah↗

USGS2014

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

We explored potential negative effects of exotic brown trout ( Salmo trutta ) on native sculpin ( Cottus sp.) on the Logan River, Utah, USA by (i) examining factors most strongly correlated with sculpin abundance (e.g., abiotic conditions or piscivory?), (ii) contrasting the extent of brown trout predation on sculpin with that by native cutthroat trout ( Oncorhynchus clarkii utah ) and (iii) estimating the number of sculpin consumed by brown trout along an elevational gradient using bioenergetics. Abundance of sculpin across reaches showed a strong ( r ≥ 0.40) and significant ( P < 0.05) correlation with physical variables describing width (positive) and gradient (negative), but not with abundance of piscivorous brown trout or cutthroat trout. In mainstem reaches containing sculpin, we found fish in 0% of age‐1, 10% of age‐2 and 33% of age‐3 and older brown trout diets. Approximately 81% of fish consumed by brown trout were sculpin. Despite a similar length–gape relationship for native cutthroat trout, we found only two fish (one sculpin and one unknown) in the diets of native cutthroat trout similar in size to age‐3 brown trout. Based on bioenergetics, we estimate that an average large (> 260 mm) brown trout consumes as many as 34 sculpin per year. Nevertheless, results suggest that sculpin abundance in this system is controlled by abiotic factors and not brown trout predation. Additional research is needed to better understand how piscivory influences brown trout invasion success, including in‐stream experiments exploring trophic dynamics and interactions between brown trout and native prey under different environmental conditions.

Utah↗

USGS2012

A study of the spawning ecology and early life history survival of Bonneville Cutthroat Trout

We completed a large‐scale field experiment in four tributaries of the Logan River, Utah, where the largest metapopulation of imperiled Bonneville cutthroat trout Oncorhynchus clarkii utah persists. We documented the spatial and temporal distributions of spawners, quantified substrate use versus substrate availability, and evaluated differences in hatch and emergence fry success between and among sites in relation to habitat characteristics. We observed considerable variability in the timing, magnitude, and duration of spawning among study areas (streams), in part as a function of a variable, multipeaked hydrograph. Nevertheless, across study areas, >70% of redds were constructed on the final descending limb of the hydrograph. Despite large differences in the amount of spawning substrate available, Bonneville cutthroat trout utilized a narrow range of substrate and sizes (3–80 mm) similar to that utilized by other subspecies of cutthroat trout, albeit biased towards larger sizes. Water temperatures generally remained below the recommended range (6–17°C) for spawning; however, the viability of this metapopulation of cutthroat trout suggests that the recommended temperature range for spawning is overestimated for this subspecies and (or) does not account for local thermal adaptation. Hatch varied from 43% to 77% and emergence survival from 39% to 65% among streams, and within‐stream variability was substantial; both survival rates declined significantly as a function of increased fine sediment concentrations. Egg development rates were nearly 50% greater in a high‐elevation tributary where redd counts were also lowest. In high, mountain systems with short growing seasons, this incubation delay likely presents a significant growth disadvantage for age‐0 trout. Our research enhances our understanding of Bonneville cutthroat trout spawning ecology and early survival and provides critical information for aiding in the development of benchmarks for their recovery. Effective conservation efforts should be directed towards minimizing anthropogenic activities that result in excess sedimentation in their critical spawning tributaries.

Utah↗