Survival and growth rates of juvenile salmonids reared in lowland streams

Abstract The aim of this study was to assess the efficiency of propagating juvenile trout, Salmo trutta L. in small lowland streams and to evaluate the impact of the environmental conditions in the streams on the juvenile fish. Brown trout (Salmo trutta fario) and sea trout (Salmo trutta trutta) early fry fed under controlled conditions were used to stock third-order lowland streams. During summer, fall, and spring catches, fry were counted, measured, and weighed. The following parameters were calculated using the data collected: fry stocking density (ind. m-2); survival; specific mortality rate (SMR); length range; mean specimen length; body weight; mean body weight; specific growth rate (SGR); body condition (Fulton’s index). The ichthyological studies were accompanied by simultaneous analyses of environmental conditions that were performed monthly, and benthic macroinvertebrates were sampled in spring and fall. No differences were observed in the biological parameters analyzed between sea trout and brown trout. Variability in environmental parameters such as temperature, oxygenation, conductivity, and stream width and depth were associated with differentiation in the biological parameters of the fry. The results clearly indicate that the considerable potential of small lowland streams for the propagation of salmonid juvenile stages is currently underexploited.

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Individual differences in dominance-related traits drive dispersal and settlement in hatchery-reared juvenile brown trout

Scientific Reports ◽

10.1038/s41598-021-86613-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jorge R. Sánchez-González ◽

Alfredo G. Nicieza

Keyword(s):

Body Size ◽

Brown Trout ◽

Environmental Conditions ◽

Salmo Trutta ◽

Spatial Scales ◽

Juvenile Fish ◽

Structured Populations ◽

Dispersal Ability ◽

Introduced Fish ◽

Juvenile Brown Trout

AbstractEffective management of exploited populations is based on an understanding of population dynamics and evolutionary processes. In spatially structured populations, dispersal is a central process that ultimately can affect population growth and viability. It can be influenced by environmental conditions, individual phenotypes, and stochastic factors. However, we have a limited knowledge of the relative contribution of these components and its interactions, and which traits can be used as reliable predictors of the dispersal ability. Here, we conducted a longitudinal field experiment aimed to identify traits which can be used as proxy for dispersal in juvenile brown trout (Salmo trutta L.). We measured body size and standard metabolic rates, and estimated body shapes for 212 hatchery-reared juvenile fish that were marked with individual codes and released in a small coastal stream in northwest Spain. We registered fish positions and distances to the releasing point after 19, 41, 60 and 158 days in the stream. We detected a high autocorrelation of dispersal distances, demonstrating that most individuals settle down relatively soon and then hold stable positions over the study period. Body size and fish shape were reliable predictors of dispersal, with bigger and more robust-set individuals being more likely to settle closer to the release site than smaller and more elongated fish. In addition, the analysis of spacing and spatial patterns indicated that the dispersal of introduced fish could affect the distribution of resident conspecifics. All together, these results suggest that stocking programs aimed to the enhancement of overexploited populations at fine spatial scales can be optimized by adjusting the size and shape of the introduced fish to specific management targets and environmental conditions.

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Unidirectional Natural Hybridization between Brown Trout (Salmo trutta) and Atlantic Salmon (S. salar) in Newfoundland

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-216 ◽

1992 ◽

Vol 49 (9) ◽

pp. 1953-1958 ◽

Cited By ~ 51

Author(s):

Colin McGowan ◽

William S. Davidson

Keyword(s):

Atlantic Salmon ◽

Brown Trout ◽

Salmo Trutta ◽

Dna Analysis ◽

Juvenile Fish ◽

Natural Hybridization ◽

Major Influence ◽

Isolating Mechanisms ◽

Brown Trout Salmo Trutta ◽

Sexually Mature

Protein electrophoresis and mitochondrial DNA analysis were used to detect the frequency and direction of natural hybridization between brown trout (Salmo trutta) and Atlantic salmon (S. salar) in nine Newfoundland rivers. In total, 37 hybrids were discovered in a sample of 792 juvenile fish for a regional frequency of 4.67%. Local frequencies ranged from 0.00 to 18.75% and were significantly heterogeneous. All of the hybrids sampled were produced from matings between female brown trout and male Atlantic salmon. Possible reasons for the breakdown of prereproductive isolating mechanisms between these species are considered. Reproductive characteristics of the populations involved appear to have a major influence on the dynamics of hybridization between these species in Newfoundland. It is proposed that an abundance of sexually mature Atlantic salmon parr in Newfoundland streams is responsible for both the frequency and direction of hybridization observed in this study.

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Spawning characteristics of brown trout and sea trout Salmo trutta L. in Kirk Burn, River Tweed, Scotland

Journal of Fish Biology ◽

10.1111/j.1095-8649.1977.tb04115.x ◽

1977 ◽

Vol 11 (3) ◽

pp. 217-229 ◽

Cited By ~ 46

Author(s):

J. S. Campbell

Keyword(s):

Brown Trout ◽

Salmo Trutta ◽

Sea Trout

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The Relation Between Growth and Food Consumption in the Brown Trout (Salmo Trutta)

Journal of Experimental Biology ◽

10.1242/jeb.16.4.446 ◽

1939 ◽

Vol 16 (4) ◽

pp. 446-473

Author(s):

F. T. K. PENTELOW

Keyword(s):

Body Weight ◽

Brown Trout ◽

Salmo Trutta ◽

Simple Relation ◽

The Body ◽

Average Weight ◽

Loss Of Weight ◽

Brown Trout Salmo Trutta ◽

Summer Growth ◽

Food Produce

1. The growth of brown trout (Salmo trutta), fed on Gammarus pulex, in their first and second years has been studied. 2. The growth in weight varies considerably from week to week but, generally speaking, it increases with increasing size of the fish. It is assumed that in these experiments the second point of inflection of the normal S-shaped growth curve was not reached because the fish were too young. 3. In all the fishes studied there was a period of slow growth during the winter and during the summer. Growth is at its maximum at temperatures between 50 and 60° F. 4. By careful adjustment of the rations it was possible to keep the body weight of the fish approximately constant from week to week. The amount of food required for this purpose varied from 51 to 270 mg./g. of body weight per week, but was mainly between 70 and 102 mg. and was apparently affected by the water temperature, being higher when the water was warmer. 5. Starved fish lost more weight at higher temperatures than at lower, but the loss of weight could not be related to the amount of food required to maintain the body weight constant at a given temperature. 6. The appetite of fully fed fish increases as the temperature rises to 60° F. but generally declines at temperatures higher than this. Between 40 and 50° F. the amount of growth made is roughly directly proportional to the amount of food eaten, but above 50° no such simple relation exists. 7. G. pulex is a very efficient food for trout; generally speaking about 5 g. of this food produce 1 g. increase in weight. If from this amount the quantity required to maintain the body weight constant is subtracted, it is found that 1 g. increase in weight is produced by about 3 g. of food available for growth. 8. The average weight of the Gammarus used as food in this experiment was 0.026 g., and it is estimated that for every gram increase of weight each fish consumed between 200 and 300 Gammarus.

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The Impact of Hydropeaking on Juvenile Brown Trout (Salmo trutta) in a Norwegian Regulated River

Sustainability ◽

10.3390/su12208670 ◽

2020 ◽

Vol 12 (20) ◽

pp. 8670

Author(s):

Svein Jakob Saltveit ◽

Åge Brabrand ◽

Ana Juárez ◽

Morten Stickler ◽

Bjørn Otto Dønnum

Keyword(s):

Power Plant ◽

Brown Trout ◽

Salmo Trutta ◽

Water Levels ◽

Regulated River ◽

Low Flow ◽

High Survival ◽

Power Station ◽

Brown Trout Salmo Trutta ◽

The Impact

The Norwegian electrical energy supply system is based on hydropower. The now deregulated energy market has led to increased use of hydropeaking production, leading to greater fluctuations in discharge and water levels below hydropower stations. The power station HOL 1, with an outlet to the Storåne River, is a large hydropeaking facility. With over 300 rapid flow increases and decreases per year since 2012, it is a river subjected to frequent hydropeaking. To quantify the stranding risk downstream of the power plant, the effect of a series of different turbine shutdown scenarios was simulated in an earlier study. The residual flow of 6 m3·s−1 and a full production of 66 m3·s−1 were considered as the baselines for the calculation of dewatered areas. A three-year study of juvenile fish density both upstream as a reference and downstream of the power plant was undertaken. There were very low densities or even an absence of brown trout (Salmo trutta) older than young-of-the-year (YoY) below the outlet of the power station, despite high densities of YoY in previous years. This is probably due to the large and rapid changes in flow below the power station. Hydropeaking has less impact on the earliest life stages of brown trout during spring and summer, as well as on spawning and egg development during winter. This is attributed spawning in late autumn occurring at a low flow seldom reached during hydropeaking. The high survival of YoY during the first summer and early autumn is likely due to a lower frequency of hydropeaking and higher residual flows, leaving a larger wetted area.

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Competition among juvenile brown trout, grayling and landlocked Atlantic salmon in flumes - predicting effects of interspecific interactions on salmon reintroduction success

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2020-0155 ◽

2020 ◽

Author(s):

Anna Hagelin ◽

Eva Bergman

Keyword(s):

Atlantic Salmon ◽

Brown Trout ◽

Salmo Trutta ◽

Interspecific Interactions ◽

Juvenile Fish ◽

Active Species ◽

Major Interest ◽

Brown Trout Salmo Trutta ◽

Riverine Habitats ◽

Juvenile Brown Trout

Abstract Worldwide declines in salmonid populations have generated major interest in conservation and restoration of wild populations and riverine habitats. Species reintroductions to previous habitats raises questions about their potential impact on these systems. In River Klarälven, landlocked Atlantic salmon (Salmo salar) has been extinct from upper reaches for over 50 years due to hydropower dams. Here we study competitive interactions between salmon, grayling (Thymallus thymallus) and brown trout (Salmo trutta), that occur in the upper reaches of the river. We examine foraging rates, aggression and activity of juvenile fish in allopatry at three different densities and in sympatry with one or both potential competitors in laboratory flumes. Salmon captured prey less frequently in the presence of brown trout and grayling, whereas grayling and brown trout were unaffected by salmon, but affected each other. Grayling was the most aggressive and active species whereas salmon the least. Consequently, re-introduction of salmon probably will have little impact on grayling and brown trout, whereas grayling and brown trout could affect the success of re-introducing salmon.

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