A synopsis of ‘hydropeaking’ studies on the response of juvenile Atlantic salmon to experimental flow alteration

Abstract

In insular Newfoundland, Canada, studies were conducted from 1999 to 2003 on the effects of 'simulated' hydropeaking power generation on juvenile Atlantic salmon (Salmo salar). In 1999, Atlantic salmon parr were released into an experimental reach below a hydroelectric facility and flow was manipulated over a range of discharge (1.0-4.2 m 3 s -1 ) during a series of 'experiments' simulating hydropeaking in both summer and fall. Fish were implanted with radio transmitters, manually tracked, precisely located (±1 m), habitat selection evaluated, and movement response determined. Experiments were continued in 2002 and 2003 to contrast response of salmon between summer and winter, the magnitude of flow changes were greater (0.7-5.2 m 3 s -1 ) and changes were made more rapidly (instantly). As discharge was increased, velocity and depth use by parr increased, and fish adapted behaviourally by increased contact with the substrate. Salmon parr also exhibited two distinct movement patterns in the summer and fall of 1999 studies; high site fidelity or considerable movement during trials. Salmon were more mobile during both static and dynamic flow conditions and throughout the diel cycle in the summer of 2002 experiment, and 2 fish were stranded and died, the only time this happened in the four series of experiments. Within each experiment generally there were no differences between movements at static high and low flows for day and night movements, with one exception, and night time movements were always greatest, again with one exception. During dynamic flow changes, within each experiment, distances moved during down ramping and up ramping were not significantly different except in the summer of 1999. Overall, comparing between experiments for up and down ramping events, distances moved in the summer of 2002 were statistically higher than for all other experiments. Not surprisingly, the home ranges of fish in the summer of 2002 were also the greatest while the smallest home ranges were in the winter of 2003. Results suggest hydropeaking regimes may be energetically costly potentially affecting over-winter survival which is related to energy reserves obtained during summer. Collectively these studies provide comprehensive information on the response of juvenile Atlantic salmon parr to hydropeaking, on both diel and seasonal scales, and will assist hydro producers and regulators design and operate hydropeaking regimes to minimize ecological impact.

Modelling Tools to Analyze and Assess the Ecological Impact of Hydropower Dams

“…It is one of the main stressors on aquatic ecosystems [58] as it can, despite its intermittent nature, modify stream banks and channel morphology, water depth, wetted area, velocity distribution, substrate composition, suspended matter, temperature, habitat structure and heterogeneity [59].…”

Attractiveness of a lateral shelter in a channel as a refuge for juvenile brown trout during hydropeaking

“…Daily peak flows can reach up to 10-40 times the base flow, which generally corresponds to the natural flow or a residual flow. The negative impacts of such artificial flow regimes have been studied for over three decades (Baumann and Klaus 2003;Scruton et al 2008). The ecological value of river reaches that are affected by hydropeaking can often be greatly reduced by significant changes in the river hydrological regime downstream of the restitution location of the turbinated water.…”

“…(Scruton et al 2005(Scruton et al , 2008). Significant differences between modified and natural flowing rivers have been observed in terms of the abundance and distribution of some sensitive invertebrate taxa, fish diversity and the energy base of the food web (Smokorowski et al 2011).…”

“…This challenge may be met by using specially designed lateral refuges in riverbanks of channelized rivers that serve both as fish shelters and stable habitats for small aquatic organisms. Fish shelters are not new and have been commonly used to mitigate the effects of high flow velocities (Scruton et al 2008). Valentin (1995) and Korman and Campana (2009) highlighted the significance of using lateral bank refuges to protect fish and other aquatic organisms from rapid variations in hydraulic parameters and to provide better growth conditions.…”

Effects of Changes in Arctic Lake and River Ice

“…This will have implications for the operational strategies of hydropower producers toward a peaking schedule, and must be considered when impacts of changes in river ice are evaluated. Generally, peaking operation of hydropower plants in rivers is considered an environmental challenge, and peaking during the ice season further increases potential problems (Scruton et al 2008). Balancing the variable production from non-storable renewables could lead to a less regular operation of the hydropower system, thereby increasing the potential problems linked to breakup and ice jamming in rivers downstream of hydropower outlets.…”