Multiscale hydrogeomorphic influences on bull trout (Salvelinus confluentus) spawning habitat

2015 ◽  
Vol 72 (4) ◽  
pp. 514-526 ◽  
Author(s):  
Jared R. Bean ◽  
Andrew C. Wilcox ◽  
William W. Woessner ◽  
Clint C. Muhlfeld
Keyword(s):  
Stream Water ◽  
Spatial Scales ◽  
Hydraulic Modeling ◽  
Considerable Proportion ◽  
Shear Stresses ◽  
Bull Trout ◽  
Spawning Habitat ◽  
Alluvial Valley ◽  
Salvelinus Confluentus ◽  
Spawning Period

We investigated multiscale hydrogeomorphic influences on the distribution and abundance of bull trout (Salvelinus confluentus) spawning in snowmelt-dominated streams of the upper Flathead River basin, northwestern Montana. Within our study reaches, bull trout tended to spawn in the finest available gravel substrates. Analysis of the mobility of these substrates, based on one-dimensional hydraulic modeling and calculation of dimensionless shear stresses, indicated that bed materials in spawning reaches would be mobilized at moderate (i.e., 2-year recurrence interval) high-flow conditions, although the asynchronous timing of the fall–winter egg incubation period and typical late spring – early summer snowmelt high flows in our study area may limit susceptibility to redd scour under current hydrologic regimes. Redd occurrence also tended to be associated with concave-up bedforms (pool tailouts) with downwelling intragravel flows. Streambed temperatures tracked stream water diurnal temperature cycles to a depth of at least 25 cm, averaging 6.1–8.1 °C in different study reaches during the spawning period. Ground water provided thermal moderation of stream water for several high-density spawning reaches. Bull trout redds were more frequent in unconfined alluvial valley reaches (8.5 versus 5.0 redds·km−1 in confined valley reaches), which were strongly influenced by hyporheic and groundwater – stream water exchange. A considerable proportion of redds were patchily distributed in confined valley reaches, however, emphasizing the influence of local physical conditions in supporting bull trout spawning habitat. Moreover, narrowing or “bounding” of these alluvial valley segments did not appear to be important. Our results suggest that geomorphic, thermal, and hydrological factors influence bull trout spawning occurrence at multiple spatial scales.

Geomorphology, hyporheic exchange, and selection of spawning habitat by bull trout (Salvelinus confluentus)

2000 ◽  
Vol 57 (7) ◽  
pp. 1470-1481 ◽  
Author(s):  
Colden V Baxter ◽  
F Richard Hauer
Keyword(s):  
Spatial Scale ◽  
Stream Water ◽  
Spatial Scales ◽  
Hyporheic Exchange ◽  
Bull Trout ◽  
Spawning Habitat ◽  
Alluvial Valley ◽  
Salvelinus Confluentus ◽  
Multiple Spatial Scales ◽  
Swan River

The distribution and abundance of bull trout (Salvelinus confluentus) spawning were affected by geomorphology and hyporheic groundwater - stream water exchange across multiple spatial scales in streams of the Swan River basin, northwestern Montana. Among spawning tributary streams, the abundance of bull trout redds increased with increased area of alluvial valley segments that were longitudinally confined by geomorphic knickpoints. Among all valley segment types, bull trout redds were primarily found in these bounded alluvial valley segments, which possessed complex patterns of hyporheic exchange and extensive upwelling zones. Bull trout used stream reaches for spawning that were strongly influenced by upwelling. However, within these selected reaches, bull trout redds were primarily located in transitional bedforms that possessed strong localized downwelling and high intragravel flow rates. The changing relationship of spawning habitat selection, in which bull trout selected upwelling zones at one spatial scale and downwelling zones at another spatial scale, emphasizes the importance of considering multiple spatial scales within a hierarchical geomorphic context when considering the ecology of this species or plans for bull trout conservation and restoration.

scholarly journals Seasonal timing of reproductive migrations in adfluvial bull trout: an assessment of sex, spawning experience, population density, and environmental factors

2018 ◽  
Vol 75 (12) ◽  
pp. 2172-2183 ◽  
Author(s):  
R. Niloshini Sinnatamby ◽  
Madalena C. Pinto ◽  
Fiona D. Johnston ◽  
Andrew J. Paul ◽  
Craig J. Mushens ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Upstream Migration ◽  
Swimming Ability ◽  
Bull Trout ◽  
Spawning Habitat ◽  
Salvelinus Confluentus ◽  
Intrinsic Factors ◽  
Migration Timing ◽  
First Time ◽  
Experienced Female

Using individual tags combined with a fish fence operated at the mouth of Smith-Dorrien Creek, the primary spawning habitat for Lower Kananaskis Lake bull trout (Salvelinus confluentus), we approximated a complete census of the spawning population from 1996 to 2000 to assess whether timing of upstream and downstream spawning migrations varied with extrinsic and intrinsic factors. The timing of both upstream and downstream migrations varied with sex, previous spawning experience, density, and temperature. Inferred spawning duration based on the predicted upstream and downstream migration dates indicated that experienced female spawners spent the least amount of time upstream and first-time spawners spent the most time upstream. No consistent differences in upstream migration timing were observed between non-repetitive and repetitive spawners. We suggest that variations in spawning migration timing observed in Lower Kananaskis Lake may be linked to environmental factors that influence upstream swimming ability and acquisition and expenditure of energy with respect to reproduction.

Detecting declines in the abundance of a bull trout (Salvelinus confluentus) population: understanding the accuracy, precision, and costs of our efforts

2009 ◽  
Vol 66 (4) ◽  
pp. 649-658 ◽  
Author(s):  
Robert Al-Chokhachy ◽  
Phaedra Budy ◽  
Mary Conner
Keyword(s):  
Spatial Scales ◽  
Sampling Effort ◽  
Bull Trout ◽  
Time Intervals ◽  
Salvelinus Confluentus ◽  
High Sampling ◽  
Empirical Field ◽  
Stage Class ◽  
Considerable Resource ◽  
Spatial Stratification

Using empirical field data for bull trout ( Salvelinus confluentus ), we evaluated the trade-off between power and sampling effort–cost using Monte Carlo simulations of commonly collected mark–recapture–resight and count data, and we estimated the power to detect changes in abundance across different time intervals. We also evaluated the effects of monitoring different components of a population and stratification methods on the precision of each method. Our results illustrate substantial variability in the relative precision, cost, and information gained from each approach. While grouping estimates by age or stage class substantially increased the precision of estimates, spatial stratification of sampling units resulted in limited increases in precision. Although mark–resight methods allowed for estimates of abundance versus indices of abundance, our results suggest snorkel surveys may be a more affordable monitoring approach across large spatial scales. Detecting a 25% decline in abundance after 5 years was not possible, regardless of technique (power = 0.80), without high sampling effort (48% of study site). Detecting a 25% decline was possible after 15 years, but still required high sampling efforts. Our results suggest detecting moderate changes in abundance of freshwater salmonids requires considerable resource and temporal commitments and highlight the difficulties of using abundance measures for monitoring bull trout populations.

Geographic distribution, species displacement, and niche overlap for lake trout and bull trout in mountain lakes

1993 ◽  
Vol 71 (2) ◽  
pp. 238-247 ◽  
Author(s):  
David B. Donald ◽  
David J. Alger
Keyword(s):  
Trophic Structure ◽  
Lake Trout ◽  
Niche Overlap ◽  
Mountain Lakes ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
East Central ◽  
Allopatric Populations ◽  
Trout Population ◽  
The One

Indigenous lacustrine populations of bull trout (Salvelinus confluentus) and lake trout (S. namaycush) are spatially separated within the southern part of the zone of distributional overlap (northern Montana, southwestern Alberta, and east-central British Columbia). In this area, lake trout occurred primarily in mountain lakes of 1032–1500 m elevation, while bull trout were found primarily in lakes between 1500 and 2200 m. Introductions of lake trout in the twentieth century and data obtained from beyond the study area indicated that both fishes can establish significant allopatric populations (more than 5% of the catch) in large, deep lakes (>8 ha in area and >8 m deep) over a wide elevation range. We tested the hypothesis that lake trout displace or exclude bull trout from lakes by determining the outcome of introductions of lake trout into two lakes that supported indigenous bull trout. Lake trout were introduced into Bow Lake in 1964, and by 1992 the bull trout population was decimated there and in another lake (Hector) situated 15 km downstream. Thus, lake trout can displace bull trout and may prevent bull trout from becoming established in certain low-elevation lakes. Population age-structure analyses also suggest that lake trout adversely affected bull trout. Bull trout populations in sympatry with lake trout, including the one extirpated from Hector Lake, had few old fish (18% were more than 5 years old; N = 40 fish from three lakes) compared with allopatric populations (49% were more than 5 years old; N = 235 fish from seven lakes). Niche overlap and the potential for competition between the two char species were substantial. In lakes with trophic structure ranging from simple to complex, bull trout and lake trout fed on similar foods and had similar ecological efficiencies (growth rates). Predation by lake trout on bull trout was not documented during the study.

Reach-scale movements of bull trout (Salvelinus confluentus) relative to hydropeaking operations in the Columbia River, Canada

Ecohydrology ◽  
2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
Mark K. Taylor ◽  
Caleb T. Hasler ◽  
Scott G. Hinch ◽  
Bronwen Lewis ◽  
Dana C. Schmidt ◽  
...  
Keyword(s):  
Columbia River ◽  
Bull Trout ◽  
Salvelinus Confluentus

scholarly journals Using decades of spawning data and hydraulic models to construct a temperature dependent resource selection function for management of an endangered salmonid

2021 ◽  
Author(s):  
Peter N Dudley ◽  
Sara N John ◽  
Miles E Daniels ◽  
Eric M. Danner
Keyword(s):  
Water Temperature ◽  
Environmental Variables ◽  
Resource Selection ◽  
Oncorhynchus Tshawytscha ◽  
Linear Models ◽  
Low Cost ◽  
Hydraulic Modeling ◽  
Selection Function ◽  
Spawning Habitat ◽  
Increasing Temperature

In North America, impassable, man-made barriers block access to salmonid spawning habitat and require costly restoration efforts in the remaining habitats. Evaluating restored spawning habitat quality requires information on salmon water velocity and depth preferences, which may vary in relation to other variables (e.g. water temperature). We demonstrate a generalizable, low cost method to gather and analyze this data by combining aerial redd surveys of winter-run Chinook salmon (Oncorhynchus tshawytscha), 2D hydraulic modeling, and generalized linear models to calculate spawning resource selection functions (RSFs). Our method permits the examination of interactions between environmental variables on habitat selection, which are frequently treated as independent. Our methods resulted in a RSF that shows interactions between both velocity and depth preference with changing temperature. Preferred depth increased and preferred velocity decreased with increasing temperature. Spawning RSFs for environmental variables may change as other environmental conditions (i.e. water temperature) change, thus it is importance to account for potential interactions when using or producing RSFs.

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