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.

Climate change and vulnerability of bull trout (Salvelinus confluentus) in a fire-prone landscape

2015 ◽  
Vol 72 (2) ◽  
pp. 304-318 ◽  
Author(s):  
Jeffrey A. Falke ◽  
Rebecca L. Flitcroft ◽  
Jason B. Dunham ◽  
Kristina M. McNyset ◽  
Paul F. Hessburg ◽  
...  
Keyword(s):  
Climate Change ◽  
Physical Habitat ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Management Actions ◽  
Trout Population ◽  
Fire Scenarios ◽  
Population Vulnerability ◽  
In Fire ◽  
Future Management

Linked atmospheric and wildfire changes will complicate future management of native coldwater fishes in fire-prone landscapes, and new approaches to management that incorporate uncertainty are needed to address this challenge. We used a Bayesian network (BN) approach to evaluate population vulnerability of bull trout (Salvelinus confluentus) in the Wenatchee River basin, Washington, USA, under current and future climate and fire scenarios. The BN was based on modeled estimates of wildfire, water temperature, and physical habitat prior to, and following, simulated fires throughout the basin. We found that bull trout population vulnerability depended on the extent to which climate effects can be at least partially offset by managing factors such as habitat connectivity and fire size. Moreover, our analysis showed that local management can significantly reduce the vulnerability of bull trout to climate change given appropriate management actions. Tools such as our BN that explicitly integrate the linked nature of climate and wildfire, and incorporate uncertainty in both input data and vulnerability estimates, will be vital in effective future management to conserve native coldwater fishes.

Mechanisms of coexistence between native bull trout (Salvelinus confluentus) and non-native lake trout (Salvelinus namaycush): inferences from pattern-oriented modeling

2012 ◽  
Vol 69 (4) ◽  
pp. 755-769 ◽  
Author(s):  
Jake M. Ferguson ◽  
Mark L. Taper ◽  
Christopher S. Guy ◽  
John M. Syslo
Keyword(s):  
Native Species ◽  
Fishery Management ◽  
Species Coexistence ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Process Models ◽  
Life History Strategies ◽  
Bull Trout ◽  
Vital Rates ◽  
Salvelinus Confluentus

Determining the ecological mechanisms that control population abundances is an important issue for the conservation of endangered and threatened species. We examined whether a threatened bull trout ( Salvelinus confluentus ) population could coexist at observed levels with the ecologically similar introduced species, lake trout ( Salvelinus namaycush ), using a pattern-oriented analysis of population dynamics models. We used a large suite of stage- and age-structured models to examine how both competitive and predatory interactions, combined with differing life-history strategies and species vital rates, drove salmonid coexistence patterns. In our models, an ontogenetic shift in juvenile bull trout resource use was the most important factor contributing to the two species coexistence; however, this coexistence occurred with reduced abundances in bull trout that increase the chances of extirpation for the native species. Observed levels of competition were found to have stronger effects than predation on population abundances. We used a pattern-oriented modeling approach to inference; this approach assumes process models that can generate patterns similar to the observed patterns are better supported than those that cannot. This methodology may find wide use on a number of data-limited fishery management and conservation problems.

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

Fecundity and Egg Size of a Brood Stock of Salvelinus fontinalis × S. namaycush Hybrids (Splake)

1974 ◽  
Vol 31 (2) ◽  
pp. 217-220 ◽  
Author(s):  
G. B. Ayles
Keyword(s):  
Egg Size ◽  
Lake Trout ◽  
Salvelinus Fontinalis ◽  
Lake Huron ◽  
Female Size ◽  
Brood Stock ◽  
Trout Population ◽  
Egg Diameter

Estimates of average egg diameter and average number of eggs per female from a brood stock of Salvelinus fontinalis × S. namaycush (splake) hybrids were 0.468 cm and 1169 eggs, respectively. Variation in egg size between females was attributable to variation in both size and age of the fish, whereas differences in fecundity were attributed only to differences in female size. At a given size a splake had more and larger eggs than have been reported for lake trout. The significance of the findings is discussed in relation to the reestablishment of a viable trout population in Lake Huron.

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