Growth and mortality of sympatric Atlantic salmon and brown trout fry in fluctuating and stable flows

Abstract

The growing demand for fossil-free energy makes hydroelectric power generation an important technology for flexible and renewable energy (Ashraf et al., 2018). Hydropower plants alter the natural flow regime of up-and downstream river reaches, however, with potential negative effects on aquatic organisms (Kuriqi et al., 2021;Poff et al., 1997). Particularly when electricity is generated to meet sub-daily fluctuations in energy demand, rapid changes in discharge downstream of hydropower plants can be extreme (Carolli et al., 2015;Cushman, 1985); these hydropeaking flow regimes, which result in rapid changes in stream flow patterns, have been shown to severely affect riverine biota (Moreira et al., 2019;Smokorowski et al., 2011;Zimmerman et al., 2010). The ecological effects of hydropeaking on riverine organisms are linked to alterations in the natural river hydrology, morphology (e.g. river depth, width, velocity, riverbed material and grain size) and water quality (e.g. temperature and turbidity) (Charmasson & Zinke, 2011;Hauer et al., 2014). Specific to fish and their instream habitat, alterations in river depths, velocity and water temperature are the major sources

Increased Temperature and Discharge Influence Overwinter Growth and Survival of Juvenile Salmonids in a Hydropeaking River: Simulating Effects of Climate Change Using Individual-Based Modelling

“…Further modelling studies to investigate the potential non-linear effects and tipping points (using more than two levels of each treatment) should prove to be useful, together with species-specific physiological parameters, to assess the combined effects of different climatechange scenarios. We demonstrated potential trends in growth and survival of sympatric salmonid populations in hydropeaking rivers [34] caused by a future environment with warmer and wetter winters in temperate areas, which may influence the relative competitive abilities of juvenile salmonid species [30,32].…”