Interactive effects of introduced Pacific salmon and brown trout on native brook trout: an experimental and modeling approach

2018 ◽  
Vol 75 (4) ◽  
pp. 538-548 ◽  
Author(s):  
Brandon S. Gerig ◽  
David N. Weber ◽  
Dominic T. Chaloner ◽  
Lillian M. McGill ◽  
Gary A. Lamberti
Keyword(s):  
Simulation Model ◽  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Pacific Salmon ◽  
Interactive Effects ◽  
Isotopic Ratios ◽  
Food Quantity ◽  
Salmon Eggs ◽  
Brown Trout Salmo Trutta

Pacific salmon (Oncoryhnchus spp.) and brown trout (Salmo trutta) are introduced species stocked in the Laurentian Great Lakes. In their native range, salmon deliver material that enhances growth, alters isotopic ratios, and increases contaminant burdens of resident fish. However, whether salmon subsidies mediate interactions between competing species is unknown. Here, we employed a mesocosm experiment and a simulation model to determine if salmon tissue consumption influences brook trout (Salvelinus fontinalis) growth, isotopic ratios, and mercury concentrations and whether these were modified by brown trout. Our results indicate that brook trout growth did not increase with provision of salmon tissue and was not reduced by brown trout. However, brook trout exhibited isotopic enrichment and increased mercury concentrations, suggesting dietary intake of salmon tissue. Because salmon eggs have a higher energy density and lower mercury concentration compared with salmon tissue, our simulation model suggests that consumption of salmon eggs rather than tissue can increase growth while reducing mercury accumulation. Overall, our results suggest that the role of introduced Pacific salmon is dependent on both food quantity and quality along with diet contaminant concentrations.

Bacterial Kidney Disease in Feral Populations of Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), and Rainbow Trout (Salmo gairdneri)

1979 ◽  
Vol 36 (11) ◽  
pp. 1370-1376 ◽  
Author(s):  
Douglas L. Mitchum ◽  
Loris E. Sherman ◽  
George T. Baxter
Keyword(s):  
Rainbow Trout ◽  
Kidney Disease ◽  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
Age Classes ◽  
Bacterial Kidney Disease ◽  
Live Fish ◽  
Brown Trout Salmo Trutta

Incidence and effects of bacterial kidney disease (BKD) were determined in wild, naturally reproducing populations of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Salmo gairdneri) in a small lake and stream system in southeastern Wyoming, USA where BKD epizootics have been observed since 1972. During 1976, dead fish were collected at three upstream stations, and 60 live fish were collected from each of 11 stations. All fish were necropsied, and virological, bacteriological, and parasitological examinations were conducted by standard methods. An indirect fluorescent antibody technique was used to detect the BKD organism in cultures and kidney tissue smears. Bacterial kidney disease was diagnosed in 100% of the dead brook trout collected. Incidence among live fish ranged from 83% at an upstream station to only 3% at the most downstream location, and was highest in brook trout and lowest in rainbow trout. Two longnose suckers (Catostomus catostomus), the only non-salmonids collected, were found negative for BKD. Clinical signs of infection and the most severe infections were found only in brook trout. Five age-classes of feral brook trout were involved in the epizootics. Since other known pathogens were essentially absent, it is believed that all deaths were due to BKD. Relationships between species susceptibility to BKD, age-classes, water chemistry and water temperatures, and certain ecological conditions are discussed. Key words: bacterial kidney disease, feral trout, epizootics, brook trout, brown trout, rainbow trout

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.

Spatial patterns in relations among brown trout (Salmo trutta) distribution, summer air temperature, and stream size in Rocky Mountain streams

1999 ◽  
Vol 56 (S1) ◽  
pp. 43-51 ◽  
Author(s):  
Frank J Rahel ◽  
Nathan P Nibbelink
Keyword(s):  
Spatial Patterns ◽  
Air Temperature ◽  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Rocky Mountain ◽  
Thermal Window ◽  
Small Streams ◽  
Brown Trout Salmo Trutta ◽  
Stream Size

Stream size interacted with mean July air temperature to influence the distribution of brown trout (Salmo trutta) in southeastern Wyoming streams. The geographic range of brown trout was positively associated with mean July air temperatures of 19-22°C. Within this thermal zone, brown trout were more likely to occur in large streams (>4 m wetted width) than in small streams. We used a geographic information system to examine spatial patterns in the distribution of anomalous sites (i.e., sites predicted to have brown trout but which lacked this species). Sites that lacked brown trout but contained brook trout (Salvelinus fontinalis) tended to be on small streams at the cold margin of the 19-22°C thermal window. Sites lacking both brown trout and brook trout tended to be on small streams clustered in three of the six study drainages. The spatial aggregation of these sites suggests that additional regional factors influence the occurrence of brown trout in southeastern Wyoming. It is hypothesized that these factors could involve land-use practices interacting with basin geology and geomorphology. Classification models that incorporate a few general habitat factors are useful for identifying stream reaches with the potential to support brown trout and for directing management efforts to sites where this potential is not realized.

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.

Ecological consequences of Great Lakes salmon subsidies for stream-resident brook and brown trout

2020 ◽  
Vol 77 (11) ◽  
pp. 1758-1771 ◽  
Author(s):  
Nathan T. Hermann ◽  
Dominic T. Chaloner ◽  
Brandon S. Gerig ◽  
Gary A. Lamberti
Keyword(s):  
Great Lakes ◽  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Pacific Salmon ◽  
Resource Subsidies ◽  
Resource Pulse ◽  
Lower Growth ◽  
Environmental Preferences ◽  
Resource Pulses

Introduced Pacific salmon (Oncorhynchus spp.) deliver novel, pulsed resource subsidies to Great Lakes streams. We explored interactions between native brook trout (Salvelinus fontinalis) and non-native brown trout (Salmo trutta) in the context of this resource pulse. Diets surveyed before and during salmon spawning showed that, regardless of species, trout consumed 4.5-fold more biomass during than before salmon runs. Brook trout grew more quickly than brown trout under controlled feeding regimes due, in part, to their higher food conversion efficiency of 36% compared with 21%. Bioenergetics model simulations explored the influence of temperature on the exploitation of resource pulses and found 35% lower growth rates and increased gorging at colder temperatures. Overall, we found evidence that brook trout and brown trout foraging and growth are modulated by the salmon resource pulse, especially through gorging on eggs. However, these species exhibit distinct physiological adaptations and environmental preferences that may influence their ultimate capacity to exploit resource pulses. The effects of environmental conditions and salmon subsidies on stream-resident trout have broader consequences for fisheries management and conservation efforts.

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