The Survival of Atlantic Salmon (<scp><i>Salmo salar</i></scp>) Eggs During Dewatering in a River Subjected to Hydropeaking

Casas‐Mulet, Roser; Saltveit, Svein Jakob; Alfredsen, Knut

doi:10.1002/rra.2827

Cited by 67 publications

(73 citation statements)

References 41 publications

(59 reference statements)

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“…Moreover, it is worth noting that the daily drying of spawning areas, which can increase eggs and juvenile fish mortality, depends more strongly on the variation of wetted area than of the rate on change of the water level (e.g. Casas‐Mulet et al , ).…”

Section: Methodsmentioning

confidence: 99%

Eco‐hydraulic modelling of the interactions between hydropeaking and river morphology

2015

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Hydropeaking related to hydropower operations produces adverse ecological effects that depend on its interaction with the channel morphology. A first quantitative attempt is proposed to investigate the eco-hydraulic response of different river morphologies to hydropeaking waves based on a two-dimensional hydraulic modelling approach. Physical habitat diversity, macroinvertebrate drift and fish stranding, all relevant for hydropeaking, are quantitatively investigated with reference to realistic hydro-morphological conditions of regulated alpine streams. Habitat diversity and fish stranding have the strongest dependence on channel morphology and show nearly opposite behaviours with increasing morphological complexity. Braided reaches are the most resilient to hydropeaking offering the highest habitat diversity and very limited base-to-peak variation of macroinvertebrate drift, while alternate bars are extremely sensitive environments to drift and offer safer regions from stranding. Transitional morphologies between single-thread and multi-thread offer the best eco-hydraulic trade-offs. The method allows quantifying to which extent same eco-hydraulic targets can be achieved by either morphological restorations or base flow increases: in transitional morphologies, identical reduction in reach-averaged stranding risk might be obtained either by halving the channel width or by a threefold base flow increase; analogously, the same improvement in macroinvertebrate-fed areas can be achieved in a channel with alternating bars either by a threefold base flow increase or by increasing 2.5 times the channel width. Such quantification of the eco-hydraulic effectiveness of complementary management strategies offers a powerful tool to support design of restoration measures in hydropeaking rivers.

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Section: Methodsmentioning

confidence: 99%

Eco‐hydraulic modelling of the interactions between hydropeaking and river morphology

2015

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“…A study by Casas‐Mulet et al . (), however, suggests that egg survival rates in areas exposed to hydropeaking will depend heavily on ground water and surface‐water dynamics. Consequently, dewatering of spawning redds due to the regulation of hydropeaking does not always cause absolute egg mortality.…”

Section: Discussionmentioning

confidence: 99%

Effects of hydropeaking on the spawning behaviour of Atlantic salmonSalmo salarand brown troutSalmo trutta

Vollset

Skoglund

Wiers

et al. 2016

Journal of Fish Biology

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An in situ camera set-up was used to study the spawning activity of Atlantic salmon Salmo salar and brown trout Salmo trutta throughout two consecutive seasons in a spawning area affected by hydropower-related pulse flows due to hydropeaking. The purpose was to test whether the flow variation discouraged spawning in shallow areas or motivated spawning into areas with elevated risk of incubation mortality. There were more S. salar observed on the spawning ground during days with high discharge. The presence of S. salar in the spawning grounds was not affected by the hydropeaking cycles of the preceding night. Female S. salar were observed preparing nests within the first hour after water discharge had increased to levels suitable for spawning. In contrast, the number of S. trutta was not correlated with flow and nest preparation was also observed at a discharge corresponding to the lowest discharge levels during a hydropeaking cycle. Survival was generally high in nests excavated the following winter, with only 5·4% suffering mortality due to dewatering. The results suggest that S. salar may respond rapidly to variable-flow conditions and utilize short windows with suitable flows for spawning. Smaller S. trutta may utilize low-flow conditions to spawn in areas that are not habitable by larger S. salar during low flow.

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“…For optimal survival in regulated rivers, discharge release operations should take into account not only man‐made changes in the hydrological regime, but also the influence of subsurface water on spawning areas (Casas‐Mulet et al . , ,b).…”

Section: Introductionmentioning

confidence: 99%

“…When moist, salmonid eggs can survive de‐watering for weeks (Saltveit & Brabrand ; Casas‐Mulet et al . ,b), but newly hatched alevins are more vulnerable and may die 4–10 h after de‐watering (Becker & Neitzel ; Becker et al . , ; Neitzel & Becker ; Reiser and White ).…”

Section: Introductionmentioning

confidence: 99%

“…The influence of hydropower regulation type and the importance of groundwater and interstitial water for the survival of eggs have been discussed previously regarding two Norwegian rivers: the Lundesokna, which is subjected to hydropeaking (Casas‐Mulet et al . ), and the Suldalslågen, which is subjected to permanent winter drawdown (Casas‐Mulet et al . ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydropower operations in groundwater‐influenced rivers: implications for Atlantic salmon, Salmo salar, early life stage development and survival

Casas‐Mulet

Alfredsen

Brabrand

et al. 2016

Fisheries Management Eco

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During their early-life stages (egg maturation, hatching, alevin development), between late autumn and 4 early spring, young Atlantic salmon are exposed to surface-groundwater interactions in the hyporheic 5 zone and may depend on influx of sub-surface water during periods of regulated low discharge for 6 survival. Two recent studies, one in a seasonally regulated river and one in a river exposed to 7 hydropeaking, displayed unexpectedly high survival of eggs in surface de-watered areas because of the 8 influx of oxygen-rich sub-surface water. Field observations of newly-hatched alevins in these two 9 rivers showed them to be more sensitive (i.e. suffered higher mortality from) to surface de-watering 10 than were eggs. Exposure to dry conditions in drawdown areas was highlighted as the main cause for 11 alevin mortality. Therefore, shorter periods of surface de-watering in the river with hydropeaking 12 resulted in higher alevin survival compared to the seasonally-regulated river when still permanently 13 drained after egg hatching. Greater consideration should be given to all early life-history stages when 14 implementing discharge release strategies, and the extent of groundwater influence and the potential 15 for flexible hydropower operations should be taken into account. 16 17 Keywords: hydropower regulation, hydropeaking, sub-surface water influx, egg survival, hatching 18 success, alevin survival 19 20

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The Survival of Atlantic Salmon (Salmo salar) Eggs During Dewatering in a River Subjected to Hydropeaking

Cited by 67 publications

References 41 publications

Eco‐hydraulic modelling of the interactions between hydropeaking and river morphology

Eco‐hydraulic modelling of the interactions between hydropeaking and river morphology

Effects of hydropeaking on the spawning behaviour of Atlantic salmonSalmo salarand brown troutSalmo trutta

Hydropower operations in groundwater‐influenced rivers: implications for Atlantic salmon, Salmo salar, early life stage development and survival

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