Low Toxicity of the Black Fly LarvicideBacillus thuringiensisvar.israelensisto Early Stages of Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), and Steelhead Trout (Oncorhynchus my kiss) following Direct and Indirect Exposure

1994 ◽  
Vol 51 (6) ◽  
pp. 1451-1458 ◽  
Author(s):  
Mark S. Wipfli ◽  
Richard W. Merritt ◽  
William W. Taylor
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Fork Length ◽  
Scanning Electron Micrographs ◽  
Steelhead Trout ◽  
Brown Trout Salmo Trutta ◽  
Low Toxicity ◽  
Carbon Dioxide Levels

Mortality of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and steelhead trout (Oncorhynchus mykiss) from eyed embryo to 82 mm fork length, exposed to Bacillus thuringiensis var. israelensis (B.t.i.) in the laboratory increased when dosages exceeded recommended rates by 12 000× or more. There was generally no toxicity difference between denatured (autoclaved) and nondenatured B.t.i. for all three trout species at all B.t.i. concentrations tested, indicating that mortality was due to formulation components and not B.t.i. toxin. The 48-h LC50values for brown and brook trout alevins ranged from 1561 to 2321 ppm for both denatured and nondenatured B.t.i. Scanning electron micrographs showed particle and mucus accumulation on gill surfaces from fish exposed to 2000 ppm B.t.i. for 4 h. Oxygen and carbon dioxide levels in blood from exposed (4000 ppm B.t.i. for 4 h) and unexposed fish were similar. Brown trout of 43 mm fork length fed excess B.t.i.-killed or live black flies (Cnephia dacotensis) ate similar quantities of each larval type, and both groups experienced similar mortalities and growth rates at 30-d postexposure.

Invasive brook trout disrupt the diel activity and aggregation patterns of native brown trout

2019 ◽  
Vol 76 (7) ◽  
pp. 1052-1059 ◽  
Author(s):  
Nicolas Larranaga ◽  
Magnus L. Wallerius ◽  
Haoyu Guo ◽  
Julien Cucherousset ◽  
Jörgen I. Johnsson
Keyword(s):  
Brown Trout ◽  
Ecosystem Functioning ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Behavioral Flexibility ◽  
Diel Activity ◽  
Aggregation Pattern ◽  
Competition Mode ◽  
Brown Trout Salmo Trutta

In European streams, native brown trout (Salmo trutta) feed primarily on aquatic prey but consume a higher proportion of terrestrial prey in sympatry with non-native brook trout (Salvelinus fontinalis). This is a rare example of diet convergence that may be associated with changes in diel activity or aggregation pattern by brown trout in sympatry. We recorded the activity and positions of brown trout from two origins and in two competition modes (allopatry versus sympatry, four combinations) placed in replicated stream enclosures for 29 days to test these hypotheses. Brown trout originating from or placed in sympatry were more diurnal and aggregated than those originating from or placed in allopatry. Changes in the diel activity of brown trout placed in a novel competition mode occurred progressively throughout the study. Thus, brown trout show strong behavioral flexibility in response to the non-native competitor and can revert to allopatric behavior when brook trout is removed from the system. These behavioral adjustments may have unsuspected effects on food webs and ecosystem functioning, which deserve further attention.

scholarly journals Interspecific association of brown trout (Salmo trutta ) with non-native brook trout (Salvelinus fontinalis ) at the fry stage

Ethology ◽  
2017 ◽  
Vol 123 (12) ◽  
pp. 933-941 ◽  
Author(s):  
Magnus Lovén Wallerius ◽  
Joacim Näslund ◽  
Barbara Koeck ◽  
Jörgen I. Johnsson
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Interspecific Association ◽  
Brown Trout Salmo Trutta

Parasites of trout from the Au Sable River, Michigan, with emphasis on the population biology of Cystidicoloides tenuissima

1986 ◽  
Vol 64 (7) ◽  
pp. 1549-1554 ◽  
Author(s):  
Patrick M. Muzzall
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Population Biology ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Seasonal Pattern ◽  
Abundant Species ◽  
Mean Intensity ◽  
Brown Trout Salmo Trutta ◽  
Hexagenia Limbata

Trout (212 brook trout, Salvelinus fontinalis, and 231 brown trout, Salmo trutta, Salmonidae) were collected from the Au Sable River, Michigan, and examined for parasites between April 1982 and July 1984. One hundred seventy-six brook trout and 153 brown trout were infected with at least one of the following parasites: Crepidostomum cooperi, Neascus sp., Eubothrium sp., Proteocephalus sp., Truttaedacnitis sp., Cystidicoloides tenuissima, Rhabdochona canadensis, Spinitectus gracilis, Epistylis sp., Trichodina sp., and Salmincola edwardsii. Cystidicoloides tenuissima, the most common and abundant species, did not exhibit a pronounced seasonal pattern in prevalence; mean intensity, however, was highest in July 1982, 1983, and 1984 in both trout species. The intensity of C. tenuissima increased as trout became older and then decreased in brook and brown trout 3 and 4 years of age, respectively. Data on the seasonality of S. gracilis and C. cooperi infecting trout are also presented. The muscles of trout were negative for parasites. Over 500 mayfly nymphs (Ephemeroptera) representing at least seven species were examined for parasites. Cystidicoloides tenuissima infected Ephemera simulans. Crepidostomum sp., Rhabdochona sp., and S. gracilis occurred in Hexagenia limbata.

Reproductive interactions between sympatric brook and brown trout in a small Minnesota stream

1995 ◽  
Vol 52 (9) ◽  
pp. 1958-1965 ◽  
Author(s):  
Peter W. Sorensen ◽  
Tim Essington ◽  
Dana E. Weigel ◽  
James R. Cardwell
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Population Census ◽  
Sexually Active ◽  
Behavioral Interactions ◽  
Brown Trout Salmo Trutta ◽  
Reproductive Activities ◽  
Redd Superimposition

The reproductive activities of sympatric brook (Salvelinus fontinalis) and brown trout (Salmo trutta) in a Minnesota stream were documented on a regular basis for 3 years to determine whether behavioral interactions between these species might influence their spawning activities and success. The spawning seasons of brook and brown trout consistently overlapped by 2–4 weeks, during which time nearly 10% of all sexually active females were simultaneously courted by males of both species. Male brook trout attempted to hybridize most frequently; however, both our behavioral observations and population census suggested that these fish had little success. There was also strong evidence of frequent redd superimposition, particularly by the later spawning and larger brown trout. Analysis of redd site habitat demonstrated that these species had overlapping preferences. Although it seems likely that attempted hybridization and redd superimposition work to the disadvantage of both species, the effects of these activities are likely to be particularly severe for the brook trout, which spawns earlier in the season, is smaller in size, and rarely survives to be old enough to spawn twice. Thus, reproductive interactions may be partially responsible for the displacement of brook trout by brown trout in many regions of North America.

Winter Habitat Utilization by Stream Resident Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta)

1986 ◽  
Vol 43 (10) ◽  
pp. 1970-1981 ◽  
Author(s):  
Richard A. Cunjak ◽  
Geoffrey Power
Keyword(s):  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Focal Point ◽  
Age Groups ◽  
Habitat Utilization ◽  
Point Sources ◽  
Energetic Cost ◽  
Brown Trout Salmo Trutta

Habitat utilization by brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) is described from three winters of underwater observations in a southern Ontario river. Older trout (>age 1) generally occupied positions in deeper and faster water than age 0+ trout. In winter, at sites of sympatry, brown trout occupied greater focal point water depths than brook trout; both species had similar focal point water velocities. At all sites, and for both age groups and species, there was a strong preference for positions beneath cover. Relative to summer, trout positions in winter were characterized by slower water velocities and greater overhead cover, In winter, most trout were in aggregations, usually in pools beneath cover and close to point sources of groundwater discharge. Gregarious behaviour appeared to increase as water temperatures decreased; no such relationship was evident in the summer. Specific strategies for overwintering varied between sites and age groups but generally conformed to the theory of energetic cost minimization for position choice. These variable patterns appear to be adaptive.

Exploitation of Self-Sustaining Ontario Stream Populations of Brown Trout (Salmo trutta) and Brook Trout (Salvelinus fontinalis)

1970 ◽  
Vol 27 (6) ◽  
pp. 1087-1102 ◽  
Author(s):  
T. Lawrence Marshall ◽  
Hugh R. MacCrimmon
Keyword(s):  
Population Structure ◽  
Brown Trout ◽  
Brook Trout ◽  
Standing Crop ◽  
Salmo Trutta ◽  
Salvelinus Fontinalis ◽  
Catch Per Unit Effort ◽  
High Quality ◽  
Exploitation Rate ◽  
Brown Trout Salmo Trutta

The August standing crop of harvestable brown trout (Salmo trutta, 90%), and brook trout (Salvelinus fontinalis, 9%) in the upper Sydenham River, Ont., was estimated at 499 trout/ha (63.2 kg/ha) during 1966 and 1967. Brown trout were of age I (68%), age II (23%), and the remainder of ages III, IV, V, and XIII. Brook trout were ages I (95%) and II only.The average annual harvest by 1501 anglers was 1135 fish (64% brown, 35% brook trout) at a rate of 0.34 fish/hr. Exploitation of the preseason standing populations of brown and brook trout was 23 and 59%, respectively. Catch per unit effort from the downriver section (all brown trout of ages II–IV and mean length of 34.0 cm) averaged 0.10 at an angling pressure of 264 hr/ha. An upriver section occupied predominantly (90%) by brown trout of age I–III and mean length of 26.8 cm yielded 0.67 trout/hr at an angling pressure of 251 hr/ha.The population structure, growth, and exploitation rate of naturalized brown trout favours its use in providing continuous angling of creditable quality in heavily fished headwater streams. Coexistence of self-sustaining populations of brown and brook trout provide a sustained, high-quality mixed fishery.

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