Habitat utilization by brook char (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) in Newfoundland streams

1983 ◽  
Vol 61 (6) ◽  
pp. 1214-1219 ◽  
Author(s):  
Richard A. Cunjak ◽  
John M. Green

Recent range extension of introduced salmonid species in insular Newfoundland has caused concern over their effects on native fish species. The present study was designed to investigate the stream habitat utilization of the exotic rainbow trout and the native brook char. Results of underwater field observations in a stream where the two species coexisted showed that brook char occupied positions with significantly lower water velocities and more cover than similar-sized rainbow trout. Brook char showed similar microhabitat preferences in a nearby stream where they were allopatric. The extent of species segregation was largely affected by local stream morphology, specifically the availability of preferred habitat. The implications for future introductions of exotic salmonids to native brook char streams are discussed.

1986 ◽  
Vol 64 (6) ◽  
pp. 1288-1291 ◽  
Author(s):  
Richard A. Cunjak ◽  
John M. Green

Interspecific behavioural interactions between paired brook char (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) were compared at different water temperatures to test the hypothesis that a species realizes a competitive advantage within its optimal thermal range. Three test temperatures were used: 19 °C (optimal temperature for rainbow trout), 13 °C (optimal temperature for brook charr), and 8 °C (below the optima for both species). Brook charr dominated rainbow trout at both 8 and 13 °C. At 19 °C, neither species displayed an obvious competitive advantage. The time (days) to the establishment of a dominance hierarchy reflected specific optimal temperatures; it was shortest for rainbow trout and brook charr at 19 and 13 °C, respectively. The implications of optimal temperatures and competitive ability are discussed in relation to habitat partitioning in the stream environment.


1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.


1979 ◽  
Vol 20 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Torill Bergsjø ◽  
Inger Nafstad ◽  
Kristian Ingebrigtsen

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