HYDROLOGIC CORRELATES OF BULL TROUT (Salvelinus confluentus) SWIMMING ACTIVITY IN A HYDROPEAKING RIVER

Abstract

There is a growing need to develop quantitative relationships between specific components of river flow and the behavioural responses of fishes. Given this, we tested for an effect of hydrologic parameters on axial swimming muscle electromyograms of bull trout (Salvelinus confluentus) in a large hydropeaking river (river discharge ranging from 0 to 1790 m3/s) while controlling for other exogenous factors such as temperature and light intensity. Hourly mean discharge had a significant positive effect (R2 = 0.13–0.31; depending on the distance from the dam) on swimming muscle activity. Within‐hour changes in river flow from 0 to 1045 m3/s did not elicit a hyperactive response in bull trout. When a subset of electromyogram transmitters were calibrated to swimming speed, we found there were periods, across a range of river discharges, when bull trout were not actively beating their tails—a behaviour documented in some bottom‐dwelling species associated with moving water. Not including these periods of rest, bull trout swam at median hourly speeds of 0.53 body lengths per second. Understanding fish behaviour in the context of their physical environment may help explain population‐level responses to hydrologic change. Copyright © 2013 John Wiley & Sons, Ltd.

Repeatability of movement behaviour in a wild salmonid revealed by telemetry

“…Details of S . confluentus capture and surgical methods are also found in the study of Taylor et al (in press).…”

“…The study site was the hydropeaking reach of the Columbia River between Revelstoke Dam (REV) and the downstream Arrow Lakes Reservoir in British Columbia, Canada. Detailed site and species descriptions are found in the study of Taylor et al (in press). Salvelinus confluentus movements were estimated from manually tracking their location during a companion study of S .…”

Effects of intra‐ and interspecific competition and hydropeaking on growth of juvenile Atlantic salmon (Salmo salar)

“…Previous studies of behavioural changes in mountain whitefish (Prosopium williamsoni) concluded that fluctuating flows were no more energetically costly than stable flows (Taylor et al 2012). Also, only minor variations in the energy expenditure of bull trout (Salvelinus confluentus) living in a large hydropeaking river were explained by the water discharge pattern, in spite of a hydropeaking ratio in flow of 0:1045 m 3 Ás À1 (Taylor et al 2014). Furthermore, there are examples of increased growth rate in fish species affected by hydropeaking conditions .…”

“…E-mail: ole.berg@ bio.ntnu.no There has been a lack of controlled experiments to investigate the long-term effects of rapid and frequent discharge changes (Young et al 2011). If fish are displaced, they may have to use a high amount of energy to return to suitable habitats, which in turn may reduce their overwinter survival (Scruton et al 2005;Taylor et al 2014). If fish are displaced, they may have to use a high amount of energy to return to suitable habitats, which in turn may reduce their overwinter survival (Scruton et al 2005;Taylor et al 2014).…”

Effect of short-term regulated temperature variations on the swimming economy of Atlantic salmon smolts

“…On one hand, ecological effects of hydropeaking on fish behaviour are well known (Taylor et al ., 2014; Alexandre et al ., 2015; Boavida et al ., 2016) On the other hand, physiological effects (e.g. swimming demand, oxygen consumption and internal temperature regulation) caused by the increased environmental variability are, until this date, still poorly understood (Geist et al ., 2005; Taylor et al ., 2014).…”