Journal
JOURNAL OF FISH BIOLOGY
Volume 88, Issue 6, Pages 2236-2250Publisher
WILEY
DOI: 10.1111/jfb.12985
Keywords
flow variation; hydro power; pulse flows; river regulation; salmonids; stranding
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Funding
- EnviPEAK within the research centre CEDREN (Centre for Environmental Design of Renewable Energy) - research centre of the Norwegian Research Council [193818, 201779]
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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. (C) 2016 The Fisheries Society of the British Isles
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