Rivers of the Boreal Uplands

L’Abée-Lund, Jan Henning; Haugland, Svein; Melvold, Kjetil; Saltveit, Svein Jakob; Eie, Jon Arne; Hvidsten, Nils Arne; Pettersen, Vegard; Faugli, Per Einar; Jensen, Arne J.; Pettersson, Lars-Evan

doi:10.1016/b978-0-12-369449-2.00015-1

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…Their economic and societal value has been classified as high to very high (Museth et al ., ). Furthermore, 26 tributaries and seven individual river reaches have been protected within the river system through the Norwegian Protection Plan for River Systems (L'Abée‐Lund et al ., ). Two power stations already exist within the 200 km main river stem (Figure ).…”

Section: Introductionmentioning

confidence: 97%

Assessing the consequences of habitat fragmentation for two migratory salmonid fishes

Junge

Museth

Hindar

et al. 2013

Aquatic Conservation

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ABSTRACT1. Man-made barriers such as dams affect the movement of aquatic species, reducing gene flow and genetic variability. Such encroachments may also lead to selective changes in life history and behaviour. Hydropower construction worldwide has fragmented many previously continuous fish habitats, leading to loss of populations and production. It is therefore important to assess potential impacts on habitats before such developments begin.2. Here, the potential ecological and evolutionary consequences of planned hydropower development on two migratory salmonid fishes -brown trout (Salmo trutta) and European grayling (Thymallus thymallus) -were assessed, combining telemetry with population genetics. Almost 200 fish were radio-tagged and tracked weekly between March and November. Using microsatellite markers, the genetic population structure was assessed and the number of migrants among different river sections identified for both species.3. Overall, both species displayed extensive within-and between-river movement, with larger home ranges in grayling than in trout. Regular movements between distinct spawning, feeding and wintering areas were common. These vital habitats were often located within areas of planned hydropower development.4. Both species exhibited significant population genetic structuring within the study area, with waterfalls acting as impassable barriers to upstream gene flow for grayling. The structuring was more developed for trout than for grayling. However, downstream gene flow was common, resulting in a highly admixed trout population below a waterfall.5. The large-scale movement patterns and extensive connectivity of the system indicate that habitat fragmentation and changes in water flow will adversely affect both species, but most strongly the trout. The reduction in water flow over large and productive stretches of the river might select for less migratory genotypes in both species. The loss of particular genotypes may reduce the biocomplexity of the system and overall population resilience.

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Section: Introductionmentioning

confidence: 97%

Assessing the consequences of habitat fragmentation for two migratory salmonid fishes

Junge

Museth

Hindar

et al. 2013

Aquatic Conservation

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“…The Vefsna watershed is located in Norway in the northern reach of the Boreal Uplands [ 28 ]. The river mouth is located in the innermost part of the Vefsnfjorden fjord at 65°51′N, 13°11′E.…”

Section: Methodsmentioning

confidence: 99%

“…Svenningdalselva has less water than Austervefsna, with mean annual discharges of 35 and 98 m 3 s −1 , respectively. The watercourse is rather steep, with several waterfalls, and an average gradient of 2.6 m km −1 [ 28 ]. The western part of the catchment (the Svenningdalen valley) consists of strongly transformed bedrocks from the Cambro-Silurian period, while the eastern catchment (Austervefsna) has little transformed bedrock from the same period, and a wide limestone belt.…”

Section: Methodsmentioning

confidence: 99%

“…The western part of the catchment (the Svenningdalen valley) consists of strongly transformed bedrocks from the Cambro-Silurian period, while the eastern catchment (Austervefsna) has little transformed bedrock from the same period, and a wide limestone belt. This influences the water quality, with higher values of total hardness, calcium, alkalinity, pH, and conductivity reported [ 28 ]. Hence, Austervefsna is slightly more productive than Svenningdalselva.…”

Section: Methodsmentioning

confidence: 99%

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Rapid evolution of genetic and phenotypic divergence in Atlantic salmon following the colonisation of two new branches of a watercourse

et al. 2017

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Background Selection acts strongly on individuals that colonise a habitat and have phenotypic traits that deviate from the local optima. Our objective was to investigate the evolutionary rates in Atlantic salmon (Salmo salar) in a river system (the Vefsna watershed in Norway), fewer than 15 generations after colonisation of two new branches of the watercourse for spawning, which were made available by construction of fish ladders in 1889.MethodsDifferences in age and size were analysed using scale samples collected by anglers. Age and size of recaptures from a tagging experiment were compared between the three branches. Furthermore, genetic analyses of scale samples collected in the three river branches during two periods were performed to evaluate whether observed differences evolved by genetic divergence over this short period, or were the result of phenotypic plasticity.ResultsWe demonstrate that evolution can be rapid when fish populations are subjected to strong selection, in spite of sympatry with their ancestral group, no physical barriers to hybridisation, and natal homing as the only reproductive isolating barrier. After fewer than 15 generations, there was evidence of genetic isolation between the two branches based on genetic variation at 96 single nucleotide polymorphism loci, and significant differences in several life history traits, including size and age at maturity. Selection against large size at maturity appears to have occurred, since large individuals were reluctant to ascend the branch with less abundant water. The estimated evolutionary rate of change in life history traits is within the upper 3 to 7% reported in other fish studies on microevolutionary rates.ConclusionsThese findings suggest that with sufficient genetic diversity, Atlantic salmon can rapidly colonise and evolve to new accessible habitats. This has profound implications for conservation and restoration of populations and habitats in order to meet evolutionary challenges, including alterations in water regime, whether altered by climate change or anthropogenic factors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-017-0298-1) contains supplementary material, which is available to authorized users.

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“…The seventh order River Suldalslågen is 22 km long, running from the lake, Suldalsvatnet (69 m a.s.l., area 28.8 km 2 ) to the inner part of the Ryfylkefjord (59°N, 6°E) at Sand (L'Abée‐Lund et al, ; Figure ). The flow is strongly influenced by the two hydropower developments in the catchment (see below).…”

Section: The River Suldalslågenmentioning

confidence: 99%

Rivers need floods: Management lessons learnt from the regulation of the Norwegian salmon river, Suldalslågen

Saltveit

Brabrand

Brittain

2019

River Research & Apps

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The Norwegian river Suldalslågen, known for its population of large‐sized Atlantic salmon (Salmo salar), has been regulated for hydropower in 1966–1967 and in 1980. The initial regulation increased winter flows and reduced summer flows and major floods. The second regulation, involving abstraction of water to a power station in an adjacent fjord, led to a strong reduction in flow. In addition to implementing different flow regimes, many remedial actions have been taken, often concurrently, making it almost impossible to detect the effect of single measures. In addition, the monitoring data have not always been consistent as regards methods and scope, and also, few data are available for preregulation conditions. This highlights major challenges in the long‐term management of regulated rivers. The absence of major floods after regulation led to increased sedimentation and encouraged carpet mosses. This reduced interstitial spaces, creating a poor habitat for salmon fry and benthic invertebrates. The knowledge gained from the wide‐ranging studies of the different flow regimes have enabled the environmental authorities to devise a final regulation regime from 2012. The final flow regime focused on biological values and functions to sustain the strain of wild, large adult salmon. The catch of wild salmon >7 kg has in fact increased since 2010 and stabilized between 1 and 2 metric tons, although the yield of large salmon prior to 1994 is unknown. In addition, the increase in the catch of large salmon is based on hatchery fish. Hatchery fish have also to a large extent contributed to the increase in the total salmon catch in recent years. Thus, that the catches in Suldalslågen are now at an all‐time high is not due to improved conditions in the river but likely to hatchery fish.

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Rivers of the Boreal Uplands

Cited by 8 publications

References 13 publications

Assessing the consequences of habitat fragmentation for two migratory salmonid fishes

Assessing the consequences of habitat fragmentation for two migratory salmonid fishes

Rapid evolution of genetic and phenotypic divergence in Atlantic salmon following the colonisation of two new branches of a watercourse

Rivers need floods: Management lessons learnt from the regulation of the Norwegian salmon river, Suldalslågen

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