Have brook trout (Salvelinus fontinalis) displaced bull trout (Salvelinus confluentus) along longitudinal gradients in central Idaho streams?

2006 ◽  
Vol 63 (1) ◽  
pp. 63-78 ◽  
Author(s):  
Bruce E Rieman ◽  
James T Peterson ◽  
Deborah L Myers
Keyword(s):  
Regression Analysis ◽  
Brook Trout ◽  
Native Species ◽  
Salvelinus Fontinalis ◽  
Hierarchical Regression ◽  
Bull Trout ◽  
Salvelinus Confluentus ◽  
Longitudinal Gradients ◽  
Local Extinctions ◽  
Central Idaho

Invasions of non-native brook trout (Salvelinus fontinalis) have the potential for upstream displacement or elimination of bull trout (Salvelinus confluentus) and other native species already threatened by habitat loss. We summarized the distribution and number of bull trout in samples from 12 streams with and without brook trout in central Idaho and used hierarchical regression analysis to consider whether brook trout have displaced bull trout along gradients of temperature and elevation. Brook trout generally were observed in higher numbers downstream of bull trout. Brook trout presence, number, and both temperature and elevation were important variables explaining the observed distributions and number of bull trout among streams. Our analyses support the hypothesis that brook trout have displaced bull trout, but results were highly variable and stream dependent. Although brook trout appeared to have displaced bull trout to higher elevations or colder temperatures, there was no clear influence on overall number of bull trout. Brook trout probably do influence bull trout populations and facilitate if not cause local extinctions, but threats probably vary strongly with environmental conditions. Bull trout in smaller streams could be more vulnerable than those in larger streams.

Assessing the effects of fish density, habitat complexity, and current velocity on interference competition between bull trout (Salvelinus confluentus) and brook trout (Salvelinus fontinalis) in an artificial stream

2013 ◽  
Vol 91 (9) ◽  
pp. 619-625 ◽  
Author(s):  
Will G. Warnock ◽  
Joseph B. Rasmussen
Keyword(s):  
Current Velocity ◽  
Brook Trout ◽  
Habitat Complexity ◽  
Salvelinus Fontinalis ◽  
Interference Competition ◽  
Foraging Strategies ◽  
Fish Density ◽  
Stream Velocity ◽  
Bull Trout ◽  
Salvelinus Confluentus

In this experiment, competition was observed among native bull trout (Salvelinus confluentus (Suckley, 1859)) and non-native brook trout (Salvelinus fontinalis (Mitchill, 1814)) in artificial streams. In intraspecific competitions, brook trout engaged in territorial interference foraging strategies, and their foraging success was correlated with occupancy of the lead position in the stream. No correlation was apparent for bull trout, most of which engaged in nonterritorial scramble foraging tactics. In interspecific competitions, four stream environments were constructed in which fish density, habitat complexity, and current velocity were altered. Bull trout outcompeted brook trout for food in simple pool habitat devoid of cover when competition was head-to-head (density = 3 fish·m−2) between the species. When competitor number was doubled in this habitat, the two became equal competitors. At this higher density, bull trout again outcompeted brook trout for food when the habitat was changed to a complex riffle with substrate cover. Brook trout were more aggressive towards bull trout than vice versa, and interspecific aggression was decreased by low density, cover, and high stream velocity. Territorial brook trout aggressively interfere with their competitor for access to resources, but the success and intensity of this tactic against bull trout may be mitigated by environmental factors.

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.

Role of climate and invasive species in structuring trout distributions in the interior Columbia River Basin, USA

2011 ◽  
Vol 68 (6) ◽  
pp. 988-1008 ◽  
Author(s):  
Seth J. Wenger ◽  
Daniel J. Isaak ◽  
Jason B. Dunham ◽  
Kurt D. Fausch ◽  
Charles H. Luce ◽  
...  
Keyword(s):  
Flow Regime ◽  
River Basin ◽  
Climate Warming ◽  
Brook Trout ◽  
Native Species ◽  
Cutthroat Trout ◽  
Columbia River ◽  
Columbia River Basin ◽  
Bull Trout

Recent and projected climate warming trends have prompted interest in impacts on coldwater fishes. We examined the role of climate (temperature and flow regime) relative to geomorphology and land use in determining the observed distributions of three trout species in the interior Columbia River Basin, USA. We considered two native species, cutthroat trout ( Oncorhynchus clarkii ) and bull trout ( Salvelinus confluentus ), as well as nonnative brook trout ( Salvelinus fontinalis ). We also examined the response of the native species to the presence of brook trout. Analyses were conducted using multilevel logistic regression applied to a geographically broad database of 4165 fish surveys. The results indicated that bull trout distributions were strongly related to climatic factors, and more weakly related to the presence of brook trout and geomorphic variables. Cutthroat trout distributions were weakly related to climate but strongly related to the presence of brook trout. Brook trout distributions were related to both climate and geomorphic variables, including proximity to unconfined valley bottoms. We conclude that brook trout and bull trout are likely to be adversely affected by climate warming, whereas cutthroat trout may be less sensitive. The results illustrate the importance of considering species interactions and flow regime alongside temperature in understanding climate effects on fish.

Abiotic and biotic factors associated with brook trout invasiveness into bull trout streams of the Canadian Rockies

2013 ◽  
Vol 70 (6) ◽  
pp. 905-914 ◽  
Author(s):  
Will G. Warnock ◽  
Joseph B. Rasmussen
Keyword(s):  
Brook Trout ◽  
Native Species ◽  
Abiotic Factors ◽  
Theoretic Approach ◽  
Bull Trout ◽  
Biotic Factors ◽  
Canadian Rockies ◽  
Negatively Associated ◽  
Trout Streams ◽  
Abiotic And Biotic Factors

An information-theoretic approach was used to determine the association between brook trout (Salvelinus fontinalis) invasiveness and a suite of abiotic and biotic factors, measured at 80 sites from 51 streams in the Canadian Rockies. The streams selected had confirmed brook trout invasions and were identified as current or historical nursery habitat for native bull trout (Salvelinus confluentus). The biomass at most sites was strongly or completely dominated (95%–100%) by one species or the other, and sites were classified as having high brook trout invasiveness (>60% of the biomass of the community relative to remnant bull trout) or low invasiveness (<40%). Among abiotic factors, high brook trout invasiveness was positively associated with stream temperature and undercut bank habitat, but negatively associated with large in-stream substrate (cobbles and boulders). Among biotic factors, brook trout invasiveness was negatively associated with co-occurring rainbow trout (Oncorhynchus mykiss) or brown trout (Salmo trutta), two other introduced species. Brook trout appear to dominate communities over native bull trout where thermal or habitat niche opportunities are provided for them, although other non-native species may restrict their invasion into bull trout streams.

Tests of Competition between Native and Introduced Salmonids in Streams: What Have We Learned?

1988 ◽  
Vol 45 (12) ◽  
pp. 2238-2246 ◽  
Author(s):  
Kurt D. Fausch
Keyword(s):  
Empirical Evidence ◽  
Brook Trout ◽  
Native Species ◽  
Salvelinus Fontinalis ◽  
Experimental Tests ◽  
Salmo Gairdneri ◽  
Review Of Literature ◽  
Inadequate Knowledge ◽  
Current Controversy ◽  
Stream Salmonids

Salmonids have been introduced worldwide to regions where they were not indigenous, usually without considering the effects on native species. This has led to many combinations of species in unnatural sympatry, some of which are suspected to interact strongly, but we currently have inadequate knowledge to allow us to predict the outcome of most such introductions. For example, despite current controversy about the potential effects of Pacific salmonids now stocked in Atlantic waters, we have only empirical evidence with which to judge whether they will be detrimental to Atlantic salmon (Salmo salar). Moreover, most experimental tests of interspecific competition between other pairs of stream salmonids have not been rigorous. A review of literature about the suspected competition between brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) in streams reveals that despite empirical evidence that water temperature and velocity play a critical interacting role in determining the outcome, most experiments have failed to elucidate the important mechanisms involved. Carefully designed experiments that compare the strength of interspecific versus intraspecific competition for different size classes will allow us to improve predictions about the effects of introduced salmonids on native species in streams.

Power, Conflict, and Effectiveness

2000 ◽  
Vol 5 (1) ◽  
pp. 28-33 ◽  
Author(s):  
M. Afzalur Rahim ◽  
David Antonioni ◽  
Krum Krumov ◽  
Snejana Ilieva
Keyword(s):  
United States ◽  
Regression Analysis ◽  
Interpersonal Conflict ◽  
The United States ◽  
Hierarchical Regression ◽  
Hierarchical Regression Analysis ◽  
Referent Power ◽  
Legitimate Power ◽  
Power Base ◽  
Effectiveness Data

This study investigated the relationships of bases of leader power (coercive, reward, legitimate, expert, and referent) and styles of handling interpersonal conflict (integrating, obliging, dominating, avoiding, and compromising) to subordinates' effectiveness. Data for this study were collected with questionnaires from the United States and Bulgaria and analyzed with hierarchical regression analysis for each country. Results indicated that in the United States referent power base of supervisors and integrating style of handling conflict of subordinates were positively associated with effectiveness. In Bulgaria, legitimate power base of supervisors was positively associated with effectiveness, but the subordinates' conflict styles were not associated with effectiveness.

scholarly journals Spotting Loneliness at School: Associations between Self-Reports and Teacher and Peer Nominations

2021 ◽  
Vol 18 (3) ◽  
pp. 971
Author(s):  
Flore Geukens ◽  
Marlies Maes ◽  
Antonius H. N. Cillessen ◽  
Hilde Colpin ◽  
Karla Van Leeuwen ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Children And Adolescents ◽  
Social Behaviors ◽  
Peer Status ◽  
Hierarchical Regression ◽  
Moderate Correlation ◽  
Hierarchical Regression Analysis ◽  
Teacher Nominations ◽  
Self Reports ◽  
Peer Nominations

In two independent studies, we aimed to examine the extent to which teacher and peer nominations of loneliness are associated with children’s and adolescents’ self-reported loneliness, respectively. Additionally, we examined whether loneliness nominations from teachers and peers were informative above and beyond peer status and social behaviors associated with loneliness. In Study 1 (N = 1594, Mage = 9.43 years), teacher nominations of loneliness showed a small to moderate correlation with children’s self-reported loneliness as assessed using the Loneliness and Social Dissatisfaction Questionnaire (LSDQ). The results of a hierarchical regression analysis showed that teacher nominations of loneliness predicted children’s self-reported loneliness above and beyond teacher nominations of peer status and social behaviors. In Study 2 (N = 350, Mage = 13.81 years), peer nominations of loneliness showed a small to moderate correlation with adolescents’ self-reported loneliness as assessed using the peer-related loneliness subscale of the Loneliness and Aloneness Scale for Children and Adolescents (LACA). The results of a hierarchical regression analysis showed that peer nominations of loneliness predicted adolescents’ self-reported loneliness above and beyond peer nominations of peer status and social behaviors. We conclude that loneliness nominations are valuable, but caution is needed when they are used exclusively to identify lonely children and adolescents.

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