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1
Lyach, Roman. "The Ten Commandments of Successful Fishery Management of Wild Brown Trout Salmo trutta Populations in Salmonid Streams in the Bohemian Region (Czech Republic)." Applied Sciences 12, no. 9 (May 3, 2022): 4602. http://dx.doi.org/10.3390/app12094602.
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The brown trout Salmo trutta is a fish species that is vulnerable to climate change and anthropogenic activities in its native range. The case studies of successful restoration of brown trout populations are rare. In this study, fishery managers who successfully restored brown trout populations are sharing their know-how and advice about their conservation strategy. Overall, twenty fishery managers were interviewed to give advice about their successful conservation practices of local brown trout populations. Using a qualitative analysis method, ten main recommendations were extracted: (1) assess the status of local brown trout populations, (2) form a union of fisheries managers and work together, (3) support the ability of the streams to retain water, (4) prevent artificial removal of water from the salmonid streams, (5) adjust the brown trout stocking strategy to individual streams, (6) set strict protection of native wild brown trout populations, (7) enforce angling bans and regulations, (8) support the rearing of brown trout in the aquaculture sector, (9) limit brown trout stocking to genetically native fish, and (10) stock smaller 0 + brown trout instead of large adult ones. In conclusion, the fishery managers agreed on the basic management steps that need to be made to conserve brown trout populations.
2
Zimmerman, Julie KH, and Bruce Vondracek. "Interactions of slimy sculpin (Cottus cognatus) with native and nonnative trout: consequences for growth." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 7 (July 1, 2006): 1526–35. http://dx.doi.org/10.1139/f06-054.
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We examined growth of native slimy sculpin (Cottus cognatus), native brook trout (Salvelinus fontinalis), and nonnative brown trout (Salmo trutta) to investigate potential interactions of a native nongame fish with native and nonnative trout. Enclosures (1 m2) were stocked with five treatments (juvenile brown trout with sculpin, juvenile brook trout with sculpin, and single species controls) at three densities. Treatments (with replication) were placed in riffles in Valley Creek, Minnesota, and growth rates were measured for six experiments. We examined the difference in growth of each species in combined species treatments compared with each species alone. We did not find evidence of inter actions between brook trout and sculpin, regardless of density or fish size. However, sculpin gained greater mass when alone than with brown trout when sculpin were >16 g. Likewise, brown trout grew more when alone than with sculpin when brown trout were >24 g. In contrast, brown trout ≤5 g grew more with sculpin compared with treatments alone. We suggest that native brook trout and sculpin coexist without evidence of competition, whereas nonnative brown trout may compete with sculpin.
3
Spens, Johan, Anders Alanärä, and Lars-Ove Eriksson. "Nonnative brook trout (Salvelinus fontinalis) and the demise of native brown trout (Salmo trutta) in northern boreal lakes: stealthy, long-term patterns?" Canadian Journal of Fisheries and Aquatic Sciences 64, no. 4 (April 1, 2007): 654–64. http://dx.doi.org/10.1139/f07-040.
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This study of 193 boreal lakes of northern Sweden suggests a long-term detrimental impact of introduced brook trout (Salvelinus fontinalis) on brown trout (Salmo trutta) populations. Thirteen of 65 (20%) brown trout populations in lakes exposed to brook trout went extinct, whereas the extinction rate in unexposed lakes was significantly lower (2%). We verified other studies that indicate that altitude strongly affects the distribution of the two species; brown trout populations in our higher altitude lakes were more sensitive to impact from brook trout. In 28 lakes above 285 m, 12 trout populations exposed to brook trout went extinct, while only one population became extinct in 37 lakes below 285 m. No effects of other environmental factors were detected (e.g., water chemistry, stocking of rainbow trout (Oncorhynchus mykiss), fish species community assembly, migration barriers, or lake morphometry on brown trout extinction). The time lag between the first record of brook trout introduction and subsequent extinction of brown trout was two decades on average (maximum 70 years). Even though further stocking of brook trout has been stopped, our analysis suggest that existing sympatric populations may continue to pose an extinction threat to brown trout.
4
Öhlund, Gunnar, Fredrik Nordwall, Erik Degerman, and Torleif Eriksson. "Life history and large-scale habitat use of brown trout (Salmo trutta) and brook trout (Salvelinus fontinalis) — implications for species replacement patterns." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 4 (April 1, 2008): 633–44. http://dx.doi.org/10.1139/f08-003.
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Simple models of temperature-mediated interference competition have generally failed to explain salmonid species replacement patterns along altitudinal gradients, a fact that emphasizes the need to link individual features and their relation to habitat characteristics to population-level dynamics. We compared life history parameters in stream-resident populations of brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) in eight boreal streams. By use of electrofishing data from 1000 sites, we analyzed and related differences in life history traits to habitat- and interaction-related patterns of growth and densities of brook and brown trout, respectively. Brown trout were competitively dominant throughout the size span of sampled sympatric sites and lowered growth rates in sympatry were mainly caused by environmental factors, revealing a link between brook trout invasions and habitat-related limitations on brown trout performance. Still, the frequency of allopatric brook trout sites increased in the smallest watersheds, indicating that localities with a high degree of brook trout dominance rarely sustain brown trout over time. Brook trout populations had higher turnover rates and proportions of mature females than brown trout populations. Our results suggest growth potential and its effect on population fecundity as a critical factor limiting competitive ability and distribution of brown trout in Swedish brook trout dominated headwaters.
5
Chivers, Douglas P., Anthony Mathiron, Janelle R. Sloychuk, and Maud C. O. Ferrari. "Responses of tadpoles to hybrid predator odours: strong maternal signatures and the potential risk/response mismatch." Proceedings of the Royal Society B: Biological Sciences 282, no. 1809 (June 22, 2015): 20150365. http://dx.doi.org/10.1098/rspb.2015.0365.
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Previous studies have established that when a prey animal knows the identity of a particular predator, it can use this knowledge to make an ‘educated guess' about similar novel predators. Such generalization of predator recognition may be particularly beneficial when prey are exposed to introduced and invasive species of predators or hybrids. Here, we examined generalization of predator recognition for woodfrog tadpoles exposed to novel trout predators. Tadpoles conditioned to recognize tiger trout, a hybrid derived from brown trout and brook trout, showed generalization of recognition of several unknown trout odours. Interestingly, the tadpoles showed stronger responses to odours of brown trout than brook trout. In a second experiment, we found that tadpoles trained to recognize brown trout showed stronger responses to tiger trout than those tadpoles trained to recognize brook trout. Given that tiger trout always have a brown trout mother and a brook trout father, these results suggest a strong maternal signature in trout odours. Tadpoles that were trained to recognize both brown trout and brook trout showed stronger response to novel tiger trout than those trained to recognize only brown trout or only brook trout. This is consistent with a peak shift in recognition, whereby cues that are intermediate between two known cues evoke stronger responses than either known cue. Given that our woodfrog tadpoles have no evolutionary or individual experience with trout, they have no way of knowing whether or not brook trout, brown trout or tiger trout are more dangerous. The differential intensity of responses that we observed to hybrid trout cues and each of the parental species indicates that there is a likely mismatch between risk and anti-predator response intensity. Future work needs to address the critical role of prey naivety on responses to invasive and introduced hybrid predators.
6
Barylo, Ye O., Yu V. Loboiko, and B. S. Barylo. "Fishery-exteriors characteristics of the brooders of brown trout, rainbow trout and brook trout." Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 21, no. 90 (April 26, 2019): 88–92. http://dx.doi.org/10.32718/nvlvet-a9015.
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This study aims to determine the reproductive indices of three types of salmon fish: brown trout (Salmo trutta morfa fario Linnaeus (1758), rainbow trout (Oncorhynchus mykiss Walbaum, 1792) and brook trout (Salvelinus fontinalis Mitchill, 1814) in aquaculture. For this purpose, 10 females and 10 males of each species were selected on an analogous basis and the main fishery-exteriors and reproductive characteristics were identified. The researching of relative fertility permit to establish that this indicator in brook trout females was 18.36% higher compared to rainbow trout, however, by 7.5% lower compared to the brown trout. It was found that brook trout eggs had less weight and size in comparison with other studied species. In particular, the weight and diameter of the eggs were 2.89 and 9.7% respectively lower than of rainbow trout, as well as 8.1 and 3.44% respectively lower compared to the brown trout. When studying the quantity of ejaculate, it was found that on average, brook trout males had 16.95% less of ejaculates compared to rainbow trout males, but 79.6% more than of brown trout males. When comparing the main indices of the brooders body of the studied species, it was found that the condition factor of the brook trout and rainbow trout females was quite high at 1.55–1.57, the brown trout one was 1.35, and the profile index respectively was 3.5, 3.52 and 4.0. The males' condition factor of brook trout, rainbow trout and brown trout was respectively 1.64, 1.52 and 1.35. Fishery-exteriors indicators met the requirements of brooders species and age specificity norms of the studied fish species.
7
Rahel, Frank J., and Nathan P. Nibbelink. "Spatial patterns in relations among brown trout (Salmo trutta) distribution, summer air temperature, and stream size in Rocky Mountain streams." Canadian Journal of Fisheries and Aquatic Sciences 56, S1 (November 30, 1999): 43–51. http://dx.doi.org/10.1139/f99-210.
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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.
8
Borgstrøm, Reidar, Sigurd Rognerud, Sondre Meland, and Bjørn Olav Rosseland. "Introduced European minnow Phoxinus phoxinus in alpine lakes may increase total mercury concentration in brown trout Salmo trutta." Fauna norvegica 41 (November 26, 2021): 41–49. http://dx.doi.org/10.5324/fn.v41i0.3967.
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In Norway, the cyprinid European minnow Phoxinus phoxinus has been spread far outside its previous natural distribution area, with lots of establishments in mountain lakes where brown trout Salmo trutta originally was the only fish species. We have analysed δ15N and total mercury (THg) concentration in brown trout from eight lakes, situated between 1031 and 1244 m a.s.l. on the Hardangervidda mountain plateau, southern Norway. One of the lakes is inhabited by brown trout and European minnow, while in the other seven lakes, brown trout is the only fish species. δ15N of brown trout were significantly higher in the population with co-existing European minnow, indicating a higher trophic position of brown trout in this population than in the allopatric populations, probably caused by piscivory, as indicated by frequent occurrence of European minnow in brown trout diet. The mercury concentrations in brown trout from this lake had values up to around 0.4 mg THg per kg wet weight. The concentrations were significantly higher than in the lakes without European minnow, and together with the δ15N values, indicating that translocation and establishment of European minnow may increase the trophic position of brown trout in previously allopatric populations, and thereby also increase the mercury level.
9
McHugh, Peter, and Phaedra Budy. "An experimental evaluation of competitive and thermal effects on brown trout (Salmo trutta) and Bonneville cutthroat trout (Oncorhynchus clarkii utah) performance along an altitudinal gradient." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 12 (December 1, 2005): 2784–95. http://dx.doi.org/10.1139/f05-184.
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Temperature-mediated competition (i.e., dominance shifts between species depending on temperature) may explain the segregation of salmonid species along altitudinal stream gradients. We evaluated this hypothesis for exotic brown trout (Salmo trutta) and native Bonneville cutthroat trout (Oncorhynchus clarkii utah) by rearing them in experimental sympatry and allopatry using enclosures constructed at six sites spaced along a 45-km segment of a mountain stream. For both species, we compared condition and growth between allopatric and sympatric treatment groups. We found that brown trout negatively affected cutthroat trout performance, whereas cutthroat trout failed to impart an effect in the reverse direction, regardless of temperature. Thus, we documented asymmetric competition between these species but found little evidence indicating that its outcome was influenced by temperature. Brown trout cutthroat trout segregation is therefore unlikely to be due to temperature-mediated competition. Instead, brown trout may have displaced cutthroat trout from downstream areas through competition or other mechanisms, while abiotic factors preclude their (brown trout) invasion of upper elevations. Given the magnitude of effect observed in our study, we recommend that brown trout receive greater consideration in cutthroat trout conservation.
10
Al-Chokhachy, Robert, David Schmetterling, Chris Clancy, Pat Saffel, Ryan Kovach, Leslie Nyce, Brad Liermann, Wade Fredenberg, and Ron Pierce. "Are brown trout replacing or displacing bull trout populations in a changing climate?" Canadian Journal of Fisheries and Aquatic Sciences 73, no. 9 (September 2016): 1395–404. http://dx.doi.org/10.1139/cjfas-2015-0293.
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Understanding how climate change may facilitate species turnover is an important step in identifying potential conservation strategies. We used data from 33 sites in western Montana to quantify climate associations with native bull trout (Salvelinus confluentus) and non-native brown trout (Salmo trutta) abundance and population growth rates (λ). We estimated λ using exponential growth state-space models and delineated study sites based on bull trout use for either spawning and rearing (SR) or foraging, migrating, and overwintering (FMO) habitat. Bull trout abundance was negatively associated with mean August stream temperatures within SR habitat (r = −0.75). Brown trout abundance was generally highest at temperatures between 12 and 14 °C. We found bull trout λ were generally stable at sites with mean August temperature below 10 °C but significantly decreasing, rare, or extirpated at 58% of the sites with temperatures exceeding 10 °C. Brown trout λ were highest in SR and sites with temperatures exceeding 12 °C. Declining bull trout λ at sites where brown trout were absent suggest brown trout are likely replacing bull trout in a warming climate.
11
Hayes, John W. "Competition for Spawning Space Between Brown (Salmo trutta) and Rainbow Trout (S. gairdneri) in a Lake Inlet Tributary, New Zealand." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 1 (January 1, 1987): 40–47. http://dx.doi.org/10.1139/f87-005.
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Effect of interference competition for spawning space on spawning success of brown (Salmo trutta) and rainbow trout (S. gairdneri) was studied in the main spawning tributary of Lake Alexandrina, New Zealand. Competition was mediated through redd superimposition and severely limited the spawning success of both species. Overall spawning success, from egg deposition to fry emergence, was 2.1% for rainbow trout and 0.2% for brown trout and was dependent on time of spawning. Brown trout spawned from April to June and rainbow trout spawned from April to October. Brown trout and early spawning rainbow trout experienced poor spawning success due to severe redd superimposition by later spawning rainbows. Late spawning rainbows experienced highest spawning success. Redd superimposition by rainbow trout caused a 94% reduction in spawning success of brown trout in an experimental section of stream. Severe intraspecific competition for spawning space, through redd super-imposition, determined pattern and timing of peak rainbow fry emergence.
12
Bazaz, Asim Iqbal, Tasaduq H. Shah, Farooz A. Bhat, Irfan Ahmad, Nafhat-ul-Arab -, Maheen Altaf, Saima Andleeb, Zaib Hafiz, Bisma Shafi, and Azra Shah. "Assessment of Spawning Fecundity and Its Relationship with Body Parameters of Rainbow Trout (Oncorhynchus mykiss) and Brown Trout (Salmo trutta fario)." International Journal of Bio-resource and Stress Management 13, no. 10 (October 31, 2022): 1115–23. http://dx.doi.org/10.23910/1.2022.3066a.
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The present investigations were carried out at Trout Culture Farm Laribal, Srinagar (J&K Govt.), India during December, 2020. Relationship between length-weight, spawning fecundity and relative fecundity was observed in rainbow trout (O. mykiss) and brown trout (S. trutta fario). The mean length of male rainbow trout was (38.77±1.38 cm) and mean length of (38.05±1.32 cm) was observed in female rainbow trout. While as, the mean length of male brown trout was (38.86±1.41 cm) and for female brown trout mean length of (37.98±1.30 cm) was observed. The mean weight of male and female rainbow trout recorded was 794.6±49.3 g and 766.3±64.3 g respectively, while as, the average weight of male and female brown trout was 772.7±41.4 g and 757.6±57.22 g respectively. The spawning fecundity female-1 of rainbow trout ranged from 2002−2804 eggs and mean relative fecundity of 3.13±0.12 g-1 body weight was observed and for brown trout the spawning fecundity female-1 fish ranged from 961 to 1604 eggs, with a relative fecundity of 1.41 g-1 body weight to 1.56 g-1 body weight. The present study recorded a significant positive correlation between total body length and total body weight of male rainbow trout (r=0.938, p<0.05) and total body length and total body weight of female rainbow trout (r=0.989, p<0.05) and for brown trout a significant positive correlation was recorded between total body length and spawning fecundity, body weight and spawning fecundity was observed. However, relative fecundity formed a significant negative correlation between total length, body weight and spawning fecundity in brown trout.
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Larranaga, Nicolas, Magnus L. Wallerius, Haoyu Guo, Julien Cucherousset, and Jörgen I. Johnsson. "Invasive brook trout disrupt the diel activity and aggregation patterns of native brown trout." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 7 (July 2019): 1052–59. http://dx.doi.org/10.1139/cjfas-2018-0110.
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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.
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Marr, J. C. A., H. L. Bergman, J. Lipton, and C. Hogstrand. "Differences in relative sensitivity of naive and metals-acclimated brown and rainbow trout exposed to metals representative of the Clark Fork River, Montana." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 9 (September 1, 1995): 2016–30. http://dx.doi.org/10.1139/f95-793.
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Naive and metals-acclimated juvenile brown (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) were exposed to a metals mixture containing zinc, copper, lead, and cadmium, to compare relative sensitivities to metals concentrations typical of the Clark Fork River, Montana. Differences in the survival responses (tolerance versus resistance) measured for naive fish indicated that the rainbow trout are more tolerant (higher 96-h LC50) of the metals mixture, yet the naive rainbow and brown trout showed similarities in resistance (mean time to death). Differences for metals-acclimated fish indicated that brown trout are more resistant. Thus, the relative sensitivity of brown and rainbow trout varies with both the survival response measured and pre-exposure effects of metals on the physiological condition of the animal. Brown trout continued to acquire metals resistance for up to 5 weeks during acclimation to chronic concentrations of the metals mixture. Hepatic metallothionein and copper residue levels were positively correlated in both naive and metals-acclimated trout, and an energetic cost of metals acclimation was evidenced by reduced weight in brown trout acclimated to the metals. In contrast, rainbow trout demonstrated the least degree of acclimation and no significant growth inhibition was observed.
15
Hitt, Nathaniel P., Erin L. Snook, and Danielle L. Massie. "Brook trout use of thermal refugia and foraging habitat influenced by brown trout." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 3 (March 2017): 406–18. http://dx.doi.org/10.1139/cjfas-2016-0255.
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The distribution of native brook trout (Salvelinus fontinalis) in eastern North America is often limited by temperature and introduced brown trout (Salmo trutta), the relative importance of which is poorly understood but critical for conservation and restoration planning. We evaluated effects of brown trout on brook trout behavior and habitat use in experimental streams across increasing temperatures (14–23 °C) with simulated groundwater upwelling zones providing thermal refugia (6–9 °C below ambient temperatures). Allopatric and sympatric trout populations increased their use of upwelling zones as ambient temperatures increased, demonstrating the importance of groundwater as thermal refugia in warming streams. Allopatric brook trout showed greater movement rates and more even spatial distributions within streams than sympatric brook trout, suggesting interference competition by brown trout for access to forage habitats located outside thermal refugia. Our results indicate that removal of introduced brown trout may facilitate native brook trout expansion and population viability in downstream reaches depending in part on the spatial configuration of groundwater upwelling zones.
16
Erdem, Ömer Alper, Başak Alkan, and Mehmet Tolga Dinçer. "Comparison on nutritional properties of wild and cultured brown trout and Atlantic salmon." Ege Journal of Fisheries and Aquatic Sciences 37, no. 1 (March 15, 2020): 37–41. http://dx.doi.org/10.12714/egejfas.37.1.05.
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Brown trout is a fish species that both is caught and is cultured. This study has presented a comparison on proximate composition, fatty acids profile and lipid quality of wild- and cultured brown trout, and Atlantic salmon. Crude protein and crude oil of Atlantic salmon were found highest than wild and cultured brown trout and significantly differences (P<0.05). Although there is no significantly difference (P<0.05) between cultured brown trout and Atlantic salmon on eicosapentaenoic acid (EPA), there are significantly differences (P<0.05) between three fish samples on linoleic acid, linolenic acid and docosahexaenoic acid (DHA) values. Cultured brown trout has given lowest oleic acid (C18:1n9c) value and ƩMUFAs (Mono unsaturated fatty acids) with 28.05% and 35.43%. Atherogenic index and thrombogenic index of all groups were found low values. Although the highest value h/H was found in Atlantic salmon, the highest value of FLQ (Flesh lipid quality) was found in cultured brown trout.
17
Rawat, M. S., Babita Bantwan, Dhyal Singh, and O. P. Gusain. "Status of brown trout (Salmo trutta fario L.) in Garhwal Himalaya with a note on it morphometric characteristics." Environment Conservation Journal 12, no. 3 (December 22, 2011): 47–52. http://dx.doi.org/10.36953/ecj.2011.120309.
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The history of introduction of brown trout in Garhwal Himalaya is 100 years. However, the scientific information on brown trout is grossly lacking. The present study is a part of investigation on various aspects of brown trout inhabiting the River Asiganga in Uttarkashi district of Uttarakhand. The status of brown trout was ascertained in River Asiganga and other reports from elsewhere in the region. The morphometric study was based on 253 fish specimens collected from River Asiganga. In addition to the 12 body measurements of the fish, red/orange and brown spots on body were also studied.
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Young, Michael K. "Mobility of brown trout in south-central Wyoming streams." Canadian Journal of Zoology 72, no. 12 (December 1, 1994): 2078–83. http://dx.doi.org/10.1139/z94-278.
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Stream-resident brown trout (Salmo trutta) have often been considered to have small home ranges. To test this hypothesis, positions of adult brown trout in two streams were monitored from mid-June to early December 1991 and from late September 1992 to early June 1993 by using radiotelemetry. Thirty-seven of the 54 brown trout that were relocated at least once had home ranges greater than 50 m, trout larger than 340 mm moved more than did smaller brown trout, and movement of all fish tended to be greater in autumn. Different movement patterns of large and small fish imply the existence of two life-history strategies.
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Arndt, Fux, Blutke, Schwaiger, El-Matbouli, Sutter, and Langenmayer. "Proliferative Kidney Disease and Proliferative Darkening Syndrome are Linked with Brown Trout (Salmo trutta fario) Mortalities in the Pre-Alpine Isar River." Pathogens 8, no. 4 (October 6, 2019): 177. http://dx.doi.org/10.3390/pathogens8040177.
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For many years, brown trout (Salmo trutta fario) mortalities within the pre-alpine Isar River in Germany were reported by the Bavarian Fisheries Association (Landesfischereiverband Bayern e.V.) and local recreational anglers during August and September. Moribund fish seemed to be affected by proliferative darkening syndrome (PDS). In addition, proliferative kidney disease (PKD) caused by Tetracapsuloides bryosalmonae was discussed. To investigate this phenomenon, the present field study monitored brown trout mortalities by daily river inspection in 2017 and 2018. Moribund brown trout (n = 31) were collected and examined using histology, immunohistochemistry, qPCR, and quantitative stereology. Our investigations identified 29 (93.5%) brown trout affected by PKD. Four brown trout (12.9%) displayed combined hepatic and splenic lesions fitting the pathology of PDS. The piscine orthoreovirus 3, suspected as causative agent of PDS, was not detectable in any of the samples. Quantitative stereological analysis of the kidneys revealed a significant increase of the renal tissue volumes with interstitial inflammation and hematopoietic hyperplasia in PKD-affected fish as compared to healthy brown trout. The identified T. bryosalmonae strain was classified as part of the North American clade by phylogenetical analysis. This study highlights PKD and PDS as contributing factors to recurrent autumnal brown trout mortalities.
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Näslund, Ingemar, Erik Degerman, and Fredrik Nordwall. "Brown trout (Salmo trutta) habitat use and life history in Swedish streams: possible effects of biotic interactions." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 4 (April 1, 1998): 1034–42. http://dx.doi.org/10.1139/f97-313.
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To test if habitat use and life history of stream-dwelling brown trout (Salmo trutta) differed between allopatric and sympatric situations, we compared three streams with differing fish communities and used data from a large national database containing electrofishing results from Swedish streams. In the three-creek study, allopatric brown trout used all habitats and shifted from nursery areas in riffles to pool habitats, where adult growth and survival were higher. Mainly females shifted habitat and this was undertaken after age 1. Sympatric brown trout under intense pressure from other fish species remained in the riffles throughout their life cycle. Under moderate pressure from other species, larger brown trout used slow-flowing habitats. Early growth was more rapid in sympatry. Sympatric brown trout also had a lower adult to juvenile growth ratio and lower adult survival and matured earlier than allopatric brown trout. The data from the nationwide database showed that frequency of occurrence and abundance of brown trout were negatively associated with the number of coexisting fish species. It was also verified that the habitat shifts between riffles and pools were more common and possibly more beneficial in terms of growth and survival in allopatry. In addition the existence of differences in juvenile growth between allopatric and sympatric populations was verified.
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Marr, J. C. A., H. L. Bergman, M. Parker, J. Lipton, D. Cacela, W. Erickson, and G. R. Phillips. "Relative sensitivity of brown and rainbow trout to pulsed exposures of an acutely lethal mixture of metals typical of the Clark Fork River, Montana." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 9 (September 1, 1995): 2005–15. http://dx.doi.org/10.1139/f95-792.
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Brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) fry and juveniles were episodically or continuously exposed to a metals mixture (Zn, Cu, Pb, Cd): the concentrations and ratios of the metals, and variations in water quality (pH, hardness), were selected to represent conditions measured during episodic storm events in the Clark Fork River, Montana. Brown trout fry were more sensitive (lower LC50) than rainbow trout fry to the metals in 8-h exposures with constant hardness and pH, but less sensitive to elevated metal concentrations in conjunction with depressed hardness and pH. Fry were more sensitive than juveniles when exposure was continuous, but neither life stage was clearly more sensitive when exposure was pulsed. Whole-body concentrations of K+ and Ca2+ but not Na+ were significantly depressed in fry exposed to metals. Results support the hypotheses that changes in water quality during thunderstorms are lethal to fry and juvenile life stages of brown and rainbow trouts and that the relative sensitivity of the species to the metals mixture may explain their distributions in the Clark Fork River. Low-frequency extreme conditions may effectively act as a bottleneck on the viability of populations whose relative sensitivities to such extremes may control distributions of species in a system.
22
Taniguchi, Yoshinori, Frank J. Rahel, Douglas C. Novinger, and Kenneth G. Gerow. "Temperature mediation of competitive interactions among three fish species that replace each other along longitudinal stream gradients." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 8 (August 1, 1998): 1894–901. http://dx.doi.org/10.1139/f98-072.
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Competitive ability changed across a range of 3-26°C among three fish species that show longitudinal replacement in Rocky Mountain streams: brook trout (Salvelinus fontinalis) at high elevations, brown trout (Salmo trutta) at middle elevations, and creek chub (Semotilus atromaculatus) at low elevations. Competitive ability was measured by food consumption and aggression in a stream tank. At 20°C, the trout species were competitively equal, and both were competitively superior to creek chub. Creek chub began to have competitive success against brook trout at 22°C and brown trout at 24°C, temperatures stressful but not lethal for the trout. Creek chub became competitively dominant over brook trout at 24°C and brown trout at 26°C, temperatures lethal to a portion of each trout species. We examined whether reduced food consumption was due to appetite loss or the presence of other species. For brook trout, interactions influenced feeding behavior at 22°C, but appetite loss became important at 24°C. For brown trout, interactions influenced feeding behavior at 24°C, but appetite loss became important at 26°C. For creek chub, there was an interaction between behavioral interactions and appetite in determining food consumption. Field data support a transition from trout to non-trout fishes at 22-25°C.
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Kocik, John F., and William W. Taylor. "Effect of juvenile steelhead (Oncorhynchus mykiss) on age-O and age-1 brown t rout (Salmo trutta) survival and growth in a sympatric nursery stream." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 1 (January 1, 1995): 105–14. http://dx.doi.org/10.1139/f95-444.
Full textAbstract:
We determined that juvenile steelhead (Oncorynchus mykiss) had little effect on the survival and growth of age-0 and age-1 brown trout (Salmo trutta) in a Lake Huron tributary. Starting in 1989, we surveyed wild brown trout juveniles in two stream sections. Unfed steelhead fry were introduced into one section in May of 1990 and 1991, establishing moderate populations. Assessments continued through 1992. Steelhead had no measurable effect on juvenile brown trout abundance or survival. Steelhead did negatively influence age-0 brown trout growth, but this effect was minor compared with intraspecific interactions and abiotic factors. We attribute much of the brown trout success to their larger size. In June sampling, brown trout were typically 42% larger than steelhead, as would be common in the region. Variability in factors such as spawner-alevin interactions or climate could alter the timing of emergence or initial abundance, causing a more substantial effect on growth and, potentially, survival. Fishery managers need to evaluate these factors for the stocks in question before combining these species.
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Mruk, A., G. Kucheruk, L. Galoyan, and N. Mykhailenko. "Study and development of methods for obtaining intergeneric hybrids of salmonids (Salmonidae (Jarocki or Schinz, 1822)) for achieving the effect of heterosis and increasing their productivity." Ribogospodarsʹka nauka Ukraïni., no. 4(58) (December 22, 2021): 40–55. http://dx.doi.org/10.15407/fsu2021.04.040.
Full textAbstract:
Purpose. To study the possibility of obtaining highly productive intergeneric salmonid hybrids between rainbow trout and brook trout; brown trout and brook trout; rainbow trout and brown trout, as well as to develop methodological approaches and determine of optimal variants of hybrid crosses. Findings. In order to obtain intergeneric hybrids, we used six variants of hybrid crosses with brood fish of three salmonids belonging to three families (Salmo, Oncorhynhus, Salvelinus). The study used age-4 female rainbow trout with average body weight of 3296.8 g, Fork length was 62.6 cm, and the average working fecundity was 7420 eggs. Age-3 rainbow trout males had an average body weight of 1613 g and an average body length of 49.8 cm; age-3 brown trout females had an average body weight of 453.8 g and average working fecundity of 1540 eggs, and males had an average weight of 458.7 g; age-3 brook trout females had an average weight of 809.7 g and a length of 38.9 cm with working fecundity of 1732 eggs, and age-4 males had an average weight of 1212.8 g and an average body length of 46.0 cm. Twelve variants of fertilization were used: six variants at normal water temperature and six variants after a temperature shock. Under natural conditions, the creation of intergeneric hybrids is almost impossible, except for variants between brown trout and brook trout, which is due to the similarity of their biology. However, the efficiency of this cross is low and economically impractical for fish farmers. When applying the temperature shock during fertilization, hybrids proved to be the most effective, where females were rainbow trout, and males were brook trout and brown trout. The average weight of young-of-the-year intergeneric hybrids was, depending on the species of fish, from 8 to 54 g. The highest results were obtained for the creation of hybrids where following broodstock was used: ♂brook trout Х ♀brown trout; ♂brown trout Х ♀rainbow trout. In these variants of crossbreeding, the survival rate of young-of-the-year during the period of cultivation was 94.8 and 92.8%, respectively. In particular, the above hybrids did not suffer from infectious diseases during the growing period. Originality. New data on the development of methods for obtaining viable offspring of newly created hybrids were obtained, and the optimal variants of crossing between females and males of these salmonids were determined. Practical value. The results can be used for artificial breeding of salmonids in specialized farms that will allow obtaining high quality products and reducing their costs. Key words:rainbow trout, brown trout, brook trout, incubation, free embryos, larvae, fry, young-of-the-year.
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Bravo, Sandra, Ken Whelan, and María Teresa Silva. "Assessment of trout populations inhabiting the Palena River, southern Chile." Latin American Journal of Aquatic Research 49, no. 1 (March 1, 2021): 29–39. http://dx.doi.org/10.3856/vol49-issue1-fulltext-2577.
Full textAbstract:
A survey of trout species was carried out to assess the trout stocks' quality inhabiting the Palena River Basin, one of the most important rivers for recreational angling in Chilean Patagonia. Six sampling campaigns were carried out over 16 selected stretches of the river between February 2012 and June 2013. A total of 912 trout were collected, 57% rainbow trout (Oncorhynchus mykiss), 33.3% brown trout (Salmo trutta), and 9.6% brook trout (Salvelinus fontinalis). Also, one tiger trout (Salmo trutta × Salvelinus fontinalis) (a hybrid between brown and brook trout) was recorded. Results showed that both rainbow trout and brown trout shared the same reaches of the river, with very similar feeding habits, while brook trout inhabited smaller and more enclosed streams. Maturity stages (V-VI) were recorded from the fish sampled over the period spring-summer-autumn in the case of rainbow trout; autumn-winter for brook trout, and summer-autumn for brook trout. One of the study's most notable features was the small size of the mature brook trout, reaching 17.5 cm in length for gravid females and 12.4 cm for mature males at age 2+. The maximum age recorded for rainbow and brown trout was 6+, with a maximum length of 69.8 and 58.5cm, respectively, while for brook trout, the maximum age recorded was 3+ for a female with a length of 29.9 cm length and 2+ for a male of 16.6 cm.
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Cucherousset, Julien, Libor Závorka, Sergine Ponsard, Régis Céréghino, and Frédéric Santoul. "Stable isotope niche convergence in coexisting native and non-native salmonids across age classes." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 8 (August 2020): 1359–65. http://dx.doi.org/10.1139/cjfas-2019-0186.
Full textAbstract:
Niche divergence resulting from coevolution is commonly believed to favour coexistence among competing species; however, recent investigations have demonstrated that an unexpected niche convergence can occur when native and non-native species coexist. Yet, our understanding of the ontogenetic characteristics of this niche convergence remains limited. In the present study, we quantified the stable isotope niche of native brown trout (Salmo trutta) in allopatry and sympatry with non-native brook trout (Salvelinus fontinalis) across four age classes. Our results demonstrated that brown trout displayed a stable isotope niche closer to brook trout in sympatry than in allopatry, which was likely driven by an increased consumption of terrestrial invertebrates by sympatric brown trout. Stable isotope niche overlap was the strongest for young-of-the-year individuals and the intensity of overlap between sympatric native brown trout and non-native brook trout decreased during ontogeny. These findings indicate that niche convergence between the species occur at the earliest age class of the native species and are maintained across ontogeny.
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Tkachenko, H., N. Kurhaluk, and J. Grudniewska. "ALTERATIONS OF LACTATE DEHYDROGENASE ACTIVITY IN THE SKELETAL MUSCLES AND CARDIAC TISSUE OF SALMONID AFTER DISINFECTING PROCEDURE WITH CHLORAMINE-T." Scientific and Technical Bulletin of the Institute of Animal Science NAAS of Ukraine, no. 125 (2021): 37–46. http://dx.doi.org/10.32900/2312-8402-2021-125-37-46.
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Chloramine-T is a widely used disinfectant for the treatment of gill diseases of fish in freshwater and can be toxic to fish. Therefore, the current study aimed to examine the safety of this disinfecting product (as it has been attracting researchers’ attention for applying in aquatic animals) for fish health using markers of aerobic and anaerobic capacity (i.e. lactate dehydrogenase activity) in the skeletal muscle and cardiac tissues of rainbow trout (Oncorhynchus mykiss Walbaum), grayling (Thymallus thymallus Linck), and brown trout (Salmo trutta m. fario). Twenty-two clinically healthy rainbow trout, twenty-one brown trout, and twenty graylings were exposed to Chloramine-T in a final concentration of 9 mg per L. The Control group of fish was handled in the same way as the exposed groups. Fish were bathed for 20 min and repeated three times every 3 days. Two days after the last bathing fish were sampled. In the skeletal muscle tissue, LDH activity was decreased in the rainbow trout and grayling after disinfection by Chloramine-T compared to the unhandled controls. On the other hand, LDH activity was increased in the skeletal muscle tissue of brown trout. In the cardiac tissue, disinfection by Chloramine-T caused the decrease of LDH activity in rainbow trout, brown trout, and grayling. Moreover, in unhandled controls, LDH activity in the cardiac tissue was higher by 107.5% (p = 0.000) in brown trout and by 57.6% (p = 0.001) in the grayling compared to the values obtained in skeletal muscles. The present investigation demonstrates the alterations in LDH activity in the skeletal muscles and cardiac tissue after the disinfecting procedure with Chloramine-T in dose 9 mg per L. Although, after disinfection, the rainbow trout, brown trout, and grayling showed decreased trends of aerobic responses in the cardiac tissue indicating adaptive response against the Chloramine-T toxicity. Similar trends were observed in the skeletal muscles of rainbow trout and grayling. On the other hand, LDH activity in the skeletal muscles of brown trout after the disinfecting procedure with Chloramine-T was increased. Therefore, these biochemical parameters can be considered as indicators for the assessment of disinfecting effects, although further studies are required for investigating the mechanism involved in this pattern.
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Chalupa, Petr, Eva Poštulková, Lenka Hadašová, and Petr Spurný. "The Influence of Fisheries Management on the Brown Trout Population in Moravice River." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 64, no. 4 (2016): 1115–23. http://dx.doi.org/10.11118/actaun201664041115.
Full textAbstract:
In 2013, an ichthyological investigation with focus on the population of brown trout (Salmo trutta m. fario) in Moravice River above Slezská Harta dam reservoir in 6 localities of two salmonid fisheries was conducted (3 locations in fishery Moravice 7 and 3 locations in fishery Moravice 8). Ichthyological investigation in 2013 found abundance of brown trout in fishery Moravice 7 1,621 pcs/ha, in fishery Moravice 8 668 pcs/ha. These results were compared with the results of ichthyological investigations from 2004 (Spurný et al. 2006) and 2012 (unpublished data) that were conducted in the same locations of salmonid fisheries of Moravice 7 and Moravice 8. Over 10 years the size structure of brown trout population has changed, which was shown as higher proportion of juvenile fish in size (TL) to 15 cm. The average abundance of brown trout with TL up to 15 cm reached in fishery Moravice 7 in 2004 15 pcs/ha (Spurný et al. 2006), in 2013 1,039 pcs/ha, in fishery Moravice 8 in 2004 719 pcs/ha and in 2012 2,234 pcs/ha. Change in size structure of population of brown trout in monitored localities between 2004, 2012 and 2013 was evaluated as statistically significant (d. f. 10; F = 12.8; P < 0.05). Ichthyologic investigations in 2004 (Spurný et al. 2006), 2012 (unpublished data) and 2013 determined also abundance of brown trout in fishing size (TL over 25 cm): 54 pcs/ha in 2004 (Spurný et al. 2006), in 2012 (unpublished data) 41 pcs/ha, and in 2013 56 pcs/ha. These values were compared with catches of anglers, and according to the results we can say that the fishing pressure had no effect on the abundance of brown trout in fishing size. Abundance of brown trout in salmonid fisheries Moravice 7 and Moravice 8 is probably affected by drought and occurrence of piscivorous predators.
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Mikheev, P. B., S. V. Prusov, J. Erkinaro, I. V. Samokhvalov, S. I. Dolotov, A. G. Potutkin, P. Orell, et al. "Tributary-Specific Contribution to a Lacustrine Mixed-Stock Fishery of Brown Trout Salmo trutta (Salmonidae) in a Diverse Sub-Arctic Watershed." Вопросы ихтиологии 63, no. 2 (March 1, 2023): 209. http://dx.doi.org/10.31857/s0042875223020157.
Full textAbstract:
Mixed-stock fisheries which simultaneously cause mortality amongst several populations of a species of fish may occur where separate stocks partially or completely overlap in the geographic area of harvest. This study aims to analyze the population-of-origin of adult and subadult adfluvial lacustrine brown trout Salmo trutta, exploited in a mixed-stock fishery in Upper Tuloma Reservoir in Eastern Fennoscandia, using otolith microchemistry. To evaluate the origin of migratory brown trout captured in these mixed-stock harvest fisheries, we undertook otolith sampling of brown trout juveniles in fluvial spawning and rearing habitats in the reservoir watershed, including 13 natal tributaries across the catchment of the reservoir in both Russia and Finland. Harvested adult and subadult brown trout otoliths were sampled from the impoundment in the central area of the reservoir and we analyzed for stock-related character differences to compare with known populations, using trace element signatures, with fish from the mixed stock fishery. The assignments-of-origin in the mixed-stock fishery-harvest samples did not follow the known distribution of populations sampled from natal streams in the watershed. For example, brown trout from the largest tributary catchments of Lotta River and Nota River were less represented in the mixed-harvest sample, which was contradictory to their contribution to the overall spawning and rearing areas of the catchment. These results point towards the importance of maintaining the diversity of different spawning and rearing tributaries required for brown trout recruitment into mixed stock fisheries, and the potential of the existence of population structure of brown trout in the reservoir catchment. Our information suggests that it is important to develop conservation and management strategies for natal habitats in multiple streams utilized by adfluvial lacustrine brown trout populations inhabiting various catchments and that are harvested in mixed-stock fisheries.
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Dürrani, Ömerhan. "Do the length-weight relationships and condition factors of farmed rainbow trout, brook, and brown trout differ from their wild counterparts?" Aquatic Research 6, no. 4 (2023): 253–59. http://dx.doi.org/10.3153/ar23024.
Full textAbstract:
This study examines the length-weight relationships (LWR) and condition factors (CF) of three farmed fish species: rainbow trout (Oncorhynchus mykiss), brook trout (Salvelinus fontinalis), and brown trout (Salmo trutta). It then compares these findings with existing literature data for their wild counterparts to gain insights into the influence of aquaculture on their growth patterns. Using a simple power function, W=α〖L_T〗^β where W represents the fish's weight, and LT represents the fish's total length, the LWR is determined. The estimated β values indicate positive allometric growth for rainbow and brook trout, whereas brown trout exhibit an isometric growth pattern. The estimated condition factors ranged from 0.992 to 1.442 for rainbow trout, 0.665 to 1.731 for brook trout, and 0.841 to 1.321 for brown trout, with significant differences observed among them (Kruskal-Wallis test, p < 0.05). Compared with literature data from their wild counterparts, notable variations in growth patterns emerge, particularly evident in rainbow and brook trout, possibly illustrating the contrasting effects of aquaculture.
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Essington, Timothy E., Peter W. Sorensen, and Dean G. Paron. "High rate of redd superimposition by brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) in a Minnesota stream cannot be explained by habitat availability alone." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 10 (October 1, 1998): 2310–16. http://dx.doi.org/10.1139/f98-109.
Full textAbstract:
This study was conducted to test the hypothesis that redd superimposition by salmonine fishes is a consequence of limited habitat availability. We monitored redd site selection by brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) for two spawning seasons in Valley Creek, Minnesota. Redd superimposition rates were high; over one half of the brook trout and one third of the brown trout superimposed redds. We tested the role of habitat availability in this process by characterizing microhabitat at sites with and without redds in four small sections of this stream and then determined whether superimposition could be explained by random dispersal of fish over available habitat. Brown trout preferred spawning sites with high flows whereas brook trout strongly preferred deep sites with upwelling groundwater. No relationship was observed between fish density and superimposition. Additionally, the observed frequency of superimposition was greater than expected by chance in six of eight instances for brown trout and in one of three instances for brook trout. Finally, a behavioral experiment provided direct evidence that females have a behavioral preference to spawn on existing redd sites, suggesting that factors other than habitat may determine redd site selection and hence superimposition.
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Piria, Marina, Ivan Špelić, Luana Velagić, Ivana Lisica, Tamara Kanjuh, Ana Marić, Ivana Maguire, Tena Radočaj, and Predrag Simonović. "Feeding Habits and Diet Overlap between Brown Trout Lineages from the Danube Basin of Croatia." Fishes 7, no. 4 (July 21, 2022): 179. http://dx.doi.org/10.3390/fishes7040179.
Full textAbstract:
Brown trout of non-native lineages have been stocked into Croatian streams and rivers primarily to meet angler demand. The diet of brown trout in the Black Sea Basin of Croatia is poorly understood, and there are no studies examining feeding competition between the Atlantic (AT) and Danube (DA) lineages of brown trout and their hybrids (HY). The aim of this study was to examine the natural diet of brown trout of both lineages and their hybrids and to compare feeding overlap. Canonical correspondence analysis was used to investigate the relationships between feeding habits of fish from different streams and of different genetic origin. The differences in variation of the consumed prey items were analysed by canonical variate analysis, and diet overlap was assessed by the Schoener index. The results indicate that stocked brown trout (AT) adapt rapidly to new habitat and food, as revealed by the consumption of a wide range of available food items and competition for food and space by taking on the feeding behaviour of wild native conspecifics. Diet overlap was also detected between brown trout of the DA and AT lineages. This study highlights the need to implement control measures to preserve and protect the native diversity of this species.
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Bylak, Aneta. "The effects of brown trout (Salmo trutta morpha fario) on habitat selection by larval Fire Salamanders (Salamandra salamandra): a predator-avoidance strategy." Canadian Journal of Zoology 96, no. 3 (March 2018): 213–19. http://dx.doi.org/10.1139/cjz-2017-0064.
Full textAbstract:
Predatory fish can have a major impact on aquatic amphibian assemblages. Knowledge regarding the influence of habitat heterogeneity on predator–prey dynamics is extensive, but not much is published on how the habitat structure influences the co-occurrence of brown trout (Salmo trutta Linnaeus, 1758 morpha fario) and Fire Salamander (Salamandra salamandra (Linnaeus, 1758)). I examined the microhabitat distribution of larval salamanders relative to the presence of brown trout and stream morphology, hypothesizing that larval salamanders will increase their habitat use in the presence of trout to avoid predation. Fish and salamanders were sampled with an electroshocker in 62 instream habitat patches. In the stream zone populated by brown trout, larval salamanders avoided high-quality habitats such as pools, whereas they strongly preferred them in the fishless zone (their densities were ∼10 times lower in pools than in riffles). Brown trout mainly occupied deeper pools. The co-occurrence of larval Fire Salamanders with trout suggests the presence of an effective predator-avoidance strategy. The predator-avoidance response and habitat-use pattern decreased interspecific overlap, leading to the use of different instream spaces. Heterogeneous habitats enable habitat partitioning between larval salamanders and brown trout, which means that the natural characteristics of streams promote coexistence between fish and amphibians.
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Bozek, Michael A., and Wayne A. Hubert. "Segregation of resident trout in streams as predicted by three habitat dimensions." Canadian Journal of Zoology 70, no. 5 (May 1, 1992): 886–90. http://dx.doi.org/10.1139/z92-126.
Full textAbstract:
We assessed the relation of three measures of habitat to the distribution of four species of Salmonidae, cutthroat trout (Oncorhynchus clarki), brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss), in streams of the central Rocky Mountains. We examined whether single measures of three habitat dimensions (climate, stream energy, and stream size) could account for current distribution patterns of four resident trout species in Wyoming. The three habitat dimensions were represented by three habitat variables: elevation, channel gradient, and wetted stream width. Considerable overlap in the ranges of elevation, gradient, and wetted width was observed among reaches where the four species were found, but differences in the mean values of these habitat features were observed among species. Using discriminant analysis, we categorized the presence and absence of individual species in stream reaches by the three habitat variables. We successfully predicted the presence of brook trout (87%), cutthroat trout (59%), brown trout (50%), and rainbow trout (39%) in streams, but the absence of each species was predicted more successfully (rainbow trout (94%), brown trout (94%), cutthroat trout (90%), and brook trout (57%)). The three habitat features were useful in describing the segregation of trout species in streams of the central Rocky Mountains.
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Olofsson, H., and H. Mosegaard. "Larger eggs in resident brown trout living in sympatry with anadromous brown trout." Ecology of Freshwater Fish 8, no. 2 (June 1999): 59–64. http://dx.doi.org/10.1111/j.1600-0633.1999.tb00054.x.
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BYRNE, C. J., C. V. HOLLAND, R. POOLE, and C. R. KENNEDY. "Comparison of the macroparasite communities of wild and stocked brown trout (Salmo trutta L.) in the west of Ireland." Parasitology 124, no. 4 (April 2002): 435–45. http://dx.doi.org/10.1017/s0031182001001330.
Full textAbstract:
The aim of the present study was to compare the helminth infra and component communities of wild and stocked brown trout in Lough Feeagh, in the west of Ireland, and also to examine the establishment and development of helminth communities in stocked brown trout. Fish were sampled in May, August and November 1997 and 1998 and an additional sample of wild brown trout was examined in April 1997. In total 217 wild trout and 122 stocked trout were examined. The acanthocephalans Acanthocephalus clavula and Pomphorhynchus laevis were the first parasite species to infect stocked trout in May 1997. In May 1998 both acanthocephalan species along with the trout specialists Eubothrium crassum and Crepidostomum farionis were the first to infect trout. Mean species richness values for stocked trout increased from May to November, in 1997 and 1998. For wild trout, mean species richness values increased from April to November, in 1997 and decreased from May to November in 1998. The parasite communities of wild trout were richer than those of stocked trout in May of both years. In August the parasite communities recorded for wild and stocked trout were similar in terms of the number of species present but differed in terms of structure, and in November the parasite communities of stocked trout were richer than those of wild trout.
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Bannon, Eileen, and Neil H. Ringler. "Optimal prey size for stream resident brown trout (Salmo trutta): tests of predictive models." Canadian Journal of Zoology 64, no. 3 (March 1, 1986): 704–13. http://dx.doi.org/10.1139/z86-104.
Full textAbstract:
The time required to handle different-sized prey (crickets) was measured in an artificial stream for eight wild brown trout (Salmo trutta L.) in two size classes (mean total lengths, 186 and 214 mm). Handling times (HTs) scaled by mouth size were described by an exponential equation: HT = 1 + 0.84e2.35(ps/ms) (ps, prey size; ms, predator (mouth) size). Cost curves based on handling time/prey weight were used to predict optimal prey lengths of 22 mm for small trout and 24 mm for large trout. A second model based on J. W. J. Wankowski's empirical results predicted slightly smaller optima. Physical constraints provided estimated minimum prey lengths of 2.8 and 3.2 mm for large and small fish, respectively; maximum prey lengths were 89 and 97 mm, respectively. We compared the predicted optimal prey size with the size distribution of invertebrates in drift and brown trout stomachs sampled in a second-order stream from July to September 1982. The most abundant prey sizes in the study stream were near the minimum size that can be effectively handled by brown trout. Prey of the predicted optimum size were rare, but feeding was size selective in spite of a limited food resource. The growth rates of these stream-dwelling brown trout were slower than the brown trout in other streams in this region. This may reflect diets consisting largely of suboptimal-sized prey.
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Muzzall, Patrick M. "Parasites of trout from the Au Sable River, Michigan, with emphasis on the population biology of Cystidicoloides tenuissima." Canadian Journal of Zoology 64, no. 7 (July 1, 1986): 1549–54. http://dx.doi.org/10.1139/z86-231.
Full textAbstract:
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.
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Ivie, Jansen, Owen George, and Scott F. Collins. "Assessing the Predatory Effects of Invasive Brown Trout on Native Rio Grande Sucker and Rio Grande Chub in Mountain Streams of New Mexico, USA." Conservation 2, no. 3 (September 6, 2022): 514–25. http://dx.doi.org/10.3390/conservation2030035.
Full textAbstract:
Invasive predators pose a critical threat to native taxa. Body size plays an important role in mediating the interactions of predator and prey. For piscivorous fishes, increased predator body size can be accompanied by the selection of increasingly larger prey or may reflect a mix of small and large prey. Knowledge of such interactions helps determine how predation affects population vital rates. Here, we assessed the predatory effects of invasive Brown Trout (Salmo trutta) on populations of native Rio Grande Sucker (Catostomus plebeius) and Rio Grande Chub (Gila pandora) in streams of the Jemez River watershed (New Mexico, USA). Trout diets were sampled every two weeks during the 2020 growing season. Predator and prey body lengths were measured to examine relationships to better understand patterns of piscivory and quantify the threat Brown Trout pose to populations of Rio Grande Chub and Rio Grande Sucker. Across all streams and sampling dates, 7% of Brown Trout diets contained fish. Predator–prey length relationships reflected a ‘wedge’ pattern, indicating that Brown Trout consumed an increasing range of prey body sizes as they grew larger. Rio Grande Sucker and Rio Grande Chub comprised 46% of consumed fishes. The findings demonstrated that Rio Grande Sucker and Rio Grande Chub experience constant predation over the growing season by Brown Trout. Moreover, our study provides evidence that these invasive predators pose a threat to the viability of Rio Grande Chub and Rio Grande Sucker populations. Conservation efforts to protect these chub and sucker populations must account for and directly address predation by invasive Brown Trout.
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Závorka, Libor, Nicolas Larranaga, Magnus Lovén Wallerius, Joacim Näslund, Barbara Koeck, Niklas Wengström, Julien Cucherousset, and Jörgen I. Johnsson. "Within-stream phenotypic divergence in head shape of brown trout associated with invasive brook trout." Biological Journal of the Linnean Society 129, no. 2 (December 21, 2019): 347–55. http://dx.doi.org/10.1093/biolinnean/blz192.
Full textAbstract:
Abstract Competition with a non-native species can lead to morphological changes in native organisms induced by phenotypic plasticity, and by selection against individuals that do not adjust their morphology to the novel selection pressure. The morphological changes in native organisms are often associated with rapid behavioural responses to competition with the invader. However, knowledge of the interaction between the behaviour and morphology of native organisms competing with a non-native species remains scarce. Here, we investigated the effect of competition with non-native brook trout Salvelinus fontinalis on head shape of native brown trout Salmo trutta in a stream system where changes in diet and territorial behaviour of sympatric brown trout have previously been demonstrated. We found that sympatric brown trout had smaller eyes, shorter lower jaws and more terminal mouth than allopatric conspecifics. These differences in head shape were highly repeatable over a period of 12 months. Apparent survival indicated that the selection on head shape of brown trout was weaker in the sympatric than in the allopatric stretch of the stream. The results suggest that these changes reinforce divergences of foraging strategies between the allopatric and sympatric brown trout, which can negatively affect their population dynamics and trophic function in the food-web.
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Jagiełło, Krzysztof, Tomasz Zalewski, Stefan Dobosz, Oliwia Michalik, and Konrad Ocalewicz. "High Rate of Deformed Larvae among Gynogenetic Brown Trout (Salmo trutta m. fario) Doubled Haploids." BioMed Research International 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/2975187.
Full textAbstract:
Mitotic gynogenesis results in the production of fully homozygous individuals in a single generation. Since inbred fish were found to exhibit an increased frequency of body deformations that may affect their survival, the main focus of this research was to evaluate the ratio of individuals with spinal deformities among gynogenetic doubled haploids (DHs) brown trout as compared to nonmanipulated heterozygous individuals. Gynogenetic development was induced by the activation of brown trout eggs by UV-irradiated homologous and heterologous (rainbow trout) spermatozoa. The subsequent exposure of the activated eggs to the high hydrostatic pressure disturbed the first cleavage in gynogenetic zygotes and enabled duplication of the maternal haploid set of chromosomes. The survival rate was significantly higher among gynogenetic brown trout hatched from eggs activated with the homologous UV-irradiated spermatozoa when compared to DHs hatched from eggs activated by the heterologous spermatozoa. More than 35% of the gynogenetic larvae exhibited body deformities, mostly lordosis and scoliosis. The percentage of malformed brown trout from the control group did not exceed 15%. The increased number of deformed larvae among DHs brown trout suggested rather a genetic background of the disease related to the fish spine deformities; however, both genetic and environmental factors were discussed as a cause of such conditions in fish.
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Hermann, Nathan T., Dominic T. Chaloner, Brandon S. Gerig, and Gary A. Lamberti. "Ecological consequences of Great Lakes salmon subsidies for stream-resident brook and brown trout." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 11 (November 2020): 1758–71. http://dx.doi.org/10.1139/cjfas-2020-0086.
Full textAbstract:
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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Lagunas, Marcos, Arnar Pálsson, Benóný Jónsson, Magnús Jóhannsson, Zophonías O. Jónsson, and Sigurður S. Snorrason. "Genetic structure and relatedness of brown trout (Salmo trutta) populations in the drainage basin of the Ölfusá river, South-Western Iceland." PeerJ 11 (September 5, 2023): e15985. http://dx.doi.org/10.7717/peerj.15985.
Full textAbstract:
Background Lake Þingvallavatn in Iceland, a part of the river Ölfusá drainage basin, was presumably populated by brown trout soon after it formed at the end of the last Ice Age. The genetic relatedness of the brown trout in Þingvallavatn to other populations in the Ölfusá drainage basin is unknown. After the building of a dam at the outlet of the lake in 1959 brown trout catches declined, though numbers have now increased. The aim of this study was to assess effects of geographic isolation and potential downstream gene flow on the genetic structure and diversity in brown trout sampled in several locations in the western side of the watershed of River Ölfusá. We hypothesized that brown trout in Lake Þingvallavatn constituted several local spawning populations connected by occasional gene flow before the damming of the lake. We also estimated the effective population size (NE) of some of these populations and tested for signs of a recent population bottleneck in Lake Þingvallavatn. Methods We sampled brown trout inhabiting four lakes and 12 rivers within and near the watershed of River Ölfusá by means of electro- and net- fishing. After stringent data filtering, 2,597 polymorphic loci obtained from ddRADseq data from 317 individuals were ascertained as putative neutral markers. Results Overall, the genetic relatedness of brown trout in the Ölfusá watershed reflected the connectivity and topography of the waterways. Ancestry proportion analyses and a phylogenetic tree revealed seven distinct clusters, some of which corresponded to small populations with reduced genetic diversity. There was no evidence of downstream gene flow from Lake Þingvallavatn, although gene flow was observed from much smaller mountain populations. Most locations showed low NE values (i.e., ~14.6 on average) while the putative anadromous trout from River Sog and the spawning population from River Öxará, that flows into Lake Þingvallavatn, showed notably higher NE values (i.e., 71.2 and 56.5, respectively). No signals of recent population bottlenecks were detected in the brown trout of Lake Þingvallavatn. Discussion This is the first time that the genetic structure and diversity of brown trout in the watershed of River Ölfusá have been assessed. Our results point towards the presence of a metapopulation in the watershed of Lake Þingvallavatn, which has been influenced by restoration efforts and is now dominated by a genetic component originated in River Öxará. Many of the locations studied represent different populations. Those that are isolated in headwater streams and lakes are genetically distinct presenting low genetic diversity, yet they can be important in increasing the genetic variation in downstream populations. These populations should be considered for conservation and direct management.
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Alimova, Aziza, Boymakhmat Kakhramanov, and Feruza Safarova. "Water quality indicators in high-density cage farming of trout." BIO Web of Conferences 65 (2023): 04003. http://dx.doi.org/10.1051/bioconf/20236504003.
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Trout fishing means raising fish in water whose temperature does not exceed +18°C under completely or partially artificial conditions. Today, several fish belonging to the salmon family are bred in cold water fisheries in the world. These are river trout (Rainbow trout - Oncorhynchus mykiss), brook trout (Brown trout - Salmo trutta), and brown trout (Brook trout - Salvelinus fontinalis). Currently, river trout breeding dominates global production. Its cultivation has been mastered in almost all regions [8]. In the article, the water quality indicators were studied during high-density breeding of trout in the cage method at the “Golden Fish” fishery LLC, located in the Khojakent reservoir in the Tashkent region of Uzbekistan. This includes water temperature, dissolved oxygen content, and water hydrogen potential, as well as information on fish growth, development, nutrition, and reproduction.
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Sorensen, Peter W., Tim Essington, Dana E. Weigel, and James R. Cardwell. "Reproductive interactions between sympatric brook and brown trout in a small Minnesota stream." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 9 (September 1, 1995): 1958–65. http://dx.doi.org/10.1139/f95-787.
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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.
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Bosakowski, Thomas, and Eric J. Wagner. "Assessment of Fin Erosion by Comparison of Relative Fin Length in Hatchery and Wild Trout in Utah." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 3 (March 1, 1994): 636–41. http://dx.doi.org/10.1139/f94-064.
Full textAbstract:
We measured all fins of 600 hatchery trout sampled from all 10 state fish hatcheries in Utah, and of wild fish sampled as controls comprising 58 rainbow trout (Oncorhynchus mykiss), 33 cutthroat trout (O. clarki), and 54 brown trout (Salmo trutta). A strong linear correlation was found between fin length and total body length (100–300 mm) for all fins of wild rainbow trout. "Relative fin length" (fin length/total body length × 100) proved to be a useful comparative measure, as this statistic was not biased by fish length in the wild fish sampled (all slopes <0.01%). Interspecific comparison of wild rainbow, cutthroat, and brown trout showed slight but statistically significant differences in some fin lengths. In intraspecific comparisons, hatchery fish had significantly shorter (10–50%) rayed fins than wild fish. The dorsal fin was most severely eroded in rainbow and brown trout, followed by the pectoral, anal, ventral, and caudal fins, in cutthroat trout the pattern was the same except that pectoral fins had more extensive erosion than dorsal fins. No species was clearly more susceptible to fin erosion in hatcheries, but the Fish Lake – DeSmet strain of rainbow trout had significantly shorter fins than other rainbow trout strains.
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Ciepiela, Lindsy R., and Annika W. Walters. "Life-history variation of two inland salmonids revealed through otolith microchemistry analysis." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 11 (November 2019): 1971–81. http://dx.doi.org/10.1139/cjfas-2018-0087.
Full textAbstract:
Increasingly, otolith microchemistry analysis is used as a tool to trace fish migrations, especially migrations of diadromous fishes. Yet, few studies have used otolith microchemistry to trace migrations in small inland watersheds, leaving major knowledge gaps in our understanding of inland fish spatial ecology. Here, we evaluate the use of tributary habitat for spawning and describe and compare fluvial brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) natal origin distribution, time spent in natal streams, and spawning site fidelity. 63% of rainbow trout and 57% of brown trout migrated after hatching. Brown trout showed greater variation in time spent in natal tributaries, suggesting that individuals are temporally distributing risk among offspring. By contrast, rainbow trout showed greater variation in natal origin, suggesting that individuals are spatially distributing risk among offspring. Our results indicate there is high inter- and intraspecific migration variation in inland salmonid populations, which may be linked to access to a mosaic of spawning and rearing habitat types.
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Duguay, Jason M., R. W. Jay Lacey, and Theodore Castro-Santos. "Influence of baffles on upstream passage of brook trout and brown trout in an experimental box culvert." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 1 (January 2019): 28–41. http://dx.doi.org/10.1139/cjfas-2017-0453.
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There is much to learn about improving baffle designs to increase successful fish passage through culverts. A fish’s motivation to attempt entry into the culvert is essential. Upon entry, successful passage will largely depend on the physiological ability of the fish to navigate the entire culvert length. In this study, the motivation of brook trout (Salvelinus fontinalis (Mitchill, 1814)) and brown trout (Salmo trutta Linnaeus, 1758) to attempt ascent of an experimental flume, which mimics a roadway culvert left bare (smooth) or fitted with either spoiler or weir baffles, is assessed. Performance, measured as maximum distance of ascent within the flume, is also quantified. The bare flume was the most motivating for brook trout, and the weirs were most motivating for brown trout. As a rule, brown trout showed less motivation to stage attempts than brook trout, except within the weir baffle treatments. Performance was greatest in the weirs for smaller trout and in the spoiler baffles for larger trout. Our findings suggest that baffle form influences passage rates at road crossings in ways previously unknown and further stresses the importance of considering fish motivation and performance together when assessing the efficacy of baffle forms.
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Woodward, Daniel F., Aïda M. Farag, Harold L. Bergman, Aaron J. DeLonay, Edward E. Little, Charlie E. Smiths, and Frederic T. Barrows. "Metals-contaminated benthic invertebrates in the Clark Fork River Montana: effects on age-0 brown trout and rainbow trout." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 9 (September 1, 1995): 1994–2004. http://dx.doi.org/10.1139/f95-791.
Full textAbstract:
Benthic organisms in the upper Clark Fork River have recently been implicated as a dietary source of metals that may be a chronic problem for young-of-the-year rainbow trout (Oncorhynchus mykiss). In this present study, early life stage brown trout (Salmo trutta) and rainbow trout were exposed for 88 d to simulated Clark Fork River water and a diet of benthic invertebrates collected from the river. These exposures resulted in reduced growth and elevated levels of metals in the whole body of both species. Concentrations of As, Cd, Cu, and Pb increased in whole brown trout; in rainbow trout, As and Cd increased in whole fish, and As also increased in liver. Brown trout on the metals-contaminated diets exhibited constipation, gut impaction, increased cell membrane damage (lipid peroxidation), decreased digestive enzyme production (zymogen), and a sloughing of intestinal mucosal epithelial cells. Rainbow trout fed the contaminated diets exhibited constipation and reduced feeding activity. We believe that the reduced standing crop of trout in the Clark Fork River results partly from chronic effects of metals contamination in benthic invertebrates that are important as food for young-of-the-year fish.
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Hanson, Chad. "Brown Trout, Pantheists and Me." Life Writing 9, no. 2 (June 2012): 221–28. http://dx.doi.org/10.1080/14484528.2012.667739.
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