Relative Activity of Brook Trout and Walleyes in Response to Flow in a Regulated River

Abstract

Coded electromyogram telemetry transmitters were used to examine the effects of varying flows on the relative activity of brook trout Salvelinus fontinalis and walleye Sander vitreus in a regulated river. The relative activity levels of two brook trout and two walleyes were continuously monitored for a minimum of 24 h, and measurements were compared with river flow values logged at nearby gauging stations. Generally, fish relative activity levels mimicked patterns of flow change, peaks in activity level corresponding to peaks in flow. Mean relative activity was generally greatest at extreme high (≥25‐m3/s) and low (<15‐m3/s) flows. High flows may have elicited hyperactivity (increased activity) as fish sought suitable refugia, increased activity to hold position in the water column, or increased feeding activity on increased levels of drifting invertebrates. Hyperactivity at low flows may have been caused by relocation due to habitat loss or ease of movement at lower flow regimes. Physiological telemetry provides researchers with a method of quantifying the immediate effects of flow changes on fish. Increasing our knowledge of the effects of river regulation on fish is essential to the development of more effective management strategies that balance ecology and economics.

Fish response to modified flow regimes in regulated rivers: research methods, effects and opportunities

“…EMG transmitters; Cooke et al, 2004a) have been used for the study of regulated rivers (e.g. Murchie and Smokorowski, 2004). Once calibrated, EMG transmitters could be used to estimate the bioenergetic costs of different flow conditions.…”

Osmoregulatory, metabolic, and nutritional condition of summer-run male Chinook salmon in relation to their fate and migratory behavior in a regulated river

“…Recent studies have demonstrated delays (Thorstad et al 2003, Keefer et al 2004, 2008, Pon et al 2009a or failure of mature adult salmon to reach spawning grounds (e.g. Gowans et al 2003, Thorstad et al 2003 and higher energetic costs for salmonids exposed to variable water flows (Murchie & Smokorowski 2004, Tiffan et al 2010 in regulated rivers. Although numerous studies have measured fish behaviors in association with hydropower operations and infrastructure, only Pon et al (2009a,b) and Roscoe et al (2011) have assessed the physiological status of free-swimming fish relative to their encountering a barrier, their ability to pass the structure, and post-passage survival.…”

Rainbow trout Oncorhynchus mykiss energetic responsesto pulsed flows in the American River, California, assessed by electromyogram telemetry

“…Some fish, however, may sustain increased swimming at peak flows. Murchie and Smokorowski (2004) recorded increased EMGs in walleye (Sander vitreus) and brook trout (Salvelinus fontinalis) as pulsed flows increased. In the laboratory we found a difference between the two types of EMG transmitters used.…”

“…Thus, it is likely that EMG generated by each myomere, and the activity of a whole segment of myomeres, will be closely correlated with their oxygen consumption rate (Weatherley et al 1982). EMG telemetry has been used to determine the energetic cost of migration (Hinch and Rand 1998;Standen et al 2002), the activity exhibited during pulses of flow in a regulated river (Murchie and Smokorowski 2004;Geist et al 2005), passage through potential barriers such as weirs, dams, and rapids (Hinch et al 1996;Quintella et al 2004), and to identify spawning activity (Brown et al 2006). For example, oxygen consumption rates inferred from EMGs showed that energy costs for sockeye salmon were highest during the dominant phases of the reproductive period and spawning (Healey et al 2003).…”

“…This work was concurrent with our radio-tracking study in the same river reach of 20 additional rainbow trout (Klimley et al 2007). From the minimal literature regarding such measurements (Murchie and Smokorowski 2004), we hypothesized that the trout's swimming speeds and energy costs would increase as river discharges increased to peak flows and that they would decrease as the river discharges decreased to pre-pulse levels.…”