The influence of redd site selection, groundwater upwelling, and over-winter incubation temperature on survival of bull trout (Salvelinus confluentus) from egg to alevin

1999 ◽  
Vol 77 (8) ◽  
pp. 1233-1239 ◽  
Author(s):  
James S Baxter ◽  
J D McPhail
Keyword(s):  
Survival Rate ◽  
Surface Water ◽  
Site Selection ◽  
Incubation Temperature ◽  
Groundwater Discharge ◽  
Population Viability ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Embryo Survival ◽  
Water Recharge

We measured survival of bull trout (Salvelinus confluentus) embryos to the alevin stage in areas selected and not selected by females for spawning. In this study we tested the hypotheses that (1) females are utilizing habitats influenced by discharging groundwater and that (2) there is a reproductive advantage to spawning at these selected sites. Embryo survival was assessed by placing fertilized eggs in capsules that could be retrieved once they were placed in selected and nonselected locations. The survival rate was significantly higher (88.6 vs. 76.1%) and less variable in the selected area, but alevin lengths did not differ significantly between areas. The selected areas were, on average, locations of groundwater discharge and higher water temperatures over the incubation period, while nonselected locations were in areas of surface-water recharge and lower water temperatures. The results suggest that appropriate reproductive habitats which offer the best incubation environments may be limited in bull trout systems, and that site selection by females may increase fitness and be critical for population viability.

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
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