D. A. Scruton

Seasonal Response of Juvenile Atlantic Salmon to Experimental Hydropeaking Power Generation in Newfoundland, Canada

Abstract Variable hydropower production leads to hydropeaking, which causes discharge fluctuations that are potentially harmful to aquatic organisms. In this study, an experimental approach was used to investigate hydropeaking effects and associated hydraulic and habitat conditions on the home range and movement of juvenile Atlantic salmon Salmo salar. Prior studies examined the responses of Atlantic salmon and brook trout Salvelinus fontinalis to experimental hydropeaking during summer and autumn. The present study focused on Atlantic salmon, involved more rapid and extreme discharge manipulation, and included winter experiments to reflect influences of reduced temperature, ice conditions, and seasonal differences in behavior and habitat selection. Experiments were conducted over a range in discharge (0.5–5.0 m3/s) that resulted in dramatic habitat changes in the wide, shallow, boulder-strewn study reach. Experiments were repeated in summer and winter; however, the winter range in discharge was narrower ...

Assessment of a retrofitted downstream fish bypass system for wild Atlantic salmon (Salmo salar) smolts and kelts at a hydroelectric facility on the Exploits River, Newfoundland, Canada

In 2002 and 2003, the Bishops Falls hydroelectric generating facility on the Exploits River, insular Newfoundland, Canada, underwent extensive refurbishing including replacement of turbines and installation of a ‘retrofitted’ bypass and fish handling system. The effectiveness of this new bypass system has been assessed during the annual downstream run of wild Atlantic salmon smolt and kelt in 2003 and 2004. In 2003, 195 smolt were radio tagged and released between June 9 and July 2, in the forebay of the hydro plant (19 releases) and one upstream (in-river) release. Fish guidance efficiency (FGE) of the system overall was 63% (123 of 195 fish) with 36 fish passing through the turbines, and six known mortalities. In 2004, between June 9 and July 2, a total of 358 smolt and 103 kelt were released in the forebay in 45 and 13 releases (n = 8 per release), respectively. The FGE of the system for smolt was 71.7% (257 of 358 fish) and for kelt was 92.3% (95 of 103 fish). In 2004, 96 tagged smolt passed through the turbines and 43 (44.8%) were detected at a downstream station confirming they had survived turbine passage, suggesting an overall survival of smolt passage of the Bishops Falls hydro facility in the order of 85%. A total of seven kelts (6.8%) passed through the turbines and were not detected 1.5 km downstream suggesting they did not survive turbine passage. Smolt spent on average 39.8 h in the forebay before exiting in 2003 and forebay residency averaged 26 h in 2004. In both years, most smolt selected their passage route, actively or passively, within the first 10 h with secondary peaks at 25–30 h and 50–55 h, corresponding to evening passage in the second and third night, after release. Few smolt were bypassed or entrained into turbines during daylight hours. In both years turbine passed smolt spent more time in the forebay suggesting the longer fish reside in the forebay the greater the likelihood of turbine entrainment. Kelt were either bypassed or turbine entrained relatively quickly, within 2 h of release, and virtually all kelts were bypassed/turbine entrained during the hours of 18:00 and 01:00. These data on fish behaviour and residency in the forebay will assist further refinement of operations of the bypass facility to optimize survival.

The effects of surgically-implanted dummy radio transmitters on the behaviour of wild Atlantic salmon smolts

The social behaviour of Atlantic salmon smolts was evaluated during their migration period under controlled conditions in an experimental stream tank. Agonistic behaviour, dominance, distance to nearest neighbour, and distance from substrate were examined pre- and post-surgical implantation of dummy radio transmitters (2.4–4.3% body weight). Smolts were able to quickly equilibrate after transmitter insertion. Social ranking changed in nine of the eleven trials with four fish, and in only one of the five trials with pairs. No significant differences were found (p>0.05) in any of the behavioural parameters measured. Overall, the only effect on smolts surgically implanted with radio transmitters was a large shift in dominance. The presence of an antenna also elicited aggressive attacks from other individuals.

Use of telemetry and hydraulic modeling to evaluate and improve fish guidance efficiency at a louver and bypass system for downstream-migrating Atlantic salmon (Salmo salar) smolts and kelts

A fish protection system has been installed in a power canal at a hydroelectric facility on the Exploits River, Grand Falls-Windsor, Newfoundland, Canada. The river has an anadromous Atlantic salmon (Salmo salar)population in the order of 30000 returning adults. A louver and bypass were installed to protect downstream migrating smolt and kelt from entering the penstocks and turbines in the power canal at the generating facility. The efficiency and effectiveness of this protection system has been evaluated since 1997 through a combination of conventional telemetry, use of a digital spectrum processing (DSP) telemetry system with multiple antennae array, floy tagging, and velocity profiling along the louver array and throughout the canal. Initial monitoring in 1997 using conventional telemetry indicated low fish guidance efficiencies (FGEs) in the area of 25% for smolt. In 1998, a DSP telemetry system was installed along the louver array to attempt to identify problem areas where fish were passing through or under the louver. This work also recorded low smolt FGEs in 1998 (24.3%). However, the DSP system did identify sites along the louver array where fish were being lost, and hydraulic measurements suggested fish loss was related to hydraulic turbulence and irregularities in the guidance velocities. In 1999, a scale model of the power canal and bypass system was constructed at the University of Waterloo Engineering Departments Hydraulic Laboratory and a number of structural and operational changes to the system were evaluated. Based on the results of laboratory hydraulic modeling and DSP telemetry, a number of changes were made to the louver and bypass, prior to operation in 1999 and 2000. Monitoring of smolt out migration in 1999 and 2000 indicated a substantial improvement in smolt FGEs to 54.0 and 65.3%, respectively, and the DSP system identified areas where further improvements could be made. This paper demonstrates the utility of a sophisticated telemetry system in the evaluation of fish protection systems and how the technology can be applied towards the optimization of the effectiveness of fish by-passes.

Seasonal Effects of Suspended Sediment on the Behavior of Juvenile Atlantic Salmon

Abstract Short-term increases in suspended sediment levels significantly influenced the behavior of juvenile Atlantic salmon in both fall and winter trials. The initial introduction of sediment (20 mg/L, or ≈15 nephelometric turbidity units [NTU]) increased foraging activity, which subsequently declined at sediment levels greater than 180 mg/L (≈35 NTU). Cover use also declined as fish emerged to forage. No fish returned to cover at sediment levels greater than 60 mg/L (≈22 NTU) in the fall trials, whereas some fish in the winter trials never emerged from cover. A rapid decline in territorial behavior and an avoidance response (i.e., alarm reaction) at sediment levels ranging from 60 to 180 mg/L (≈22-42 NTU) were also noted in fall trials but not winter trials. Seasonal differences in the response of juvenile Atlantic salmon to suspended sediments may be explained by temperature-related changes in diel activity patterns.

Comparison between PIT and radio telemetry to evaluate winter habitat use and activity patterns of juvenile Atlantic salmon and brown trout

Winter habitat use and activity patterns of juvenile Atlantic salmon and brown trout were analysed in a comparative study between Passive Integrated Transponder (PIT) technology, radio telemetry and underwater observation by snorkelling. Two study periods were conducted in Stoney River, Newfoundland, Canada. During Study period I, 49 juvenile Atlantic salmon (fork length: 11.0–18.0 cm) and 7 brown trout (11.0–17.3 cm) were tagged with PIT tags and/or radio transmitters in late winter of 2004. During Study period II, 18 juvenile Atlantic salmon (fork length: 12.0–18.4 cm) and 23 brown trout (10.9–20.8 cm) were tagged and tracked twice a day at 10:00 h and 22:00 h on five consecutive days in late winter of 2005. From the 56 fish released during Study period I, on average 19.6 ± 6.0% of the PIT tagged fish and 99.3 ± 2.2% of the radio tagged fish were relocated during any given survey. Over the Study period II, 39% of fish emigrated from the study site. PIT technology had an efficiency of 39.2 ± 14.1% to detect the remaining fish. In contrast, radio telemetry relocated on average 96.9 ± 6.5% of the tagged fish whereas by snorkelling on average only 4.1 ± 5.6% of the tagged fish were observed. PIT telemetry may however be more efficient in smaller, less heterogeneous streams. The advantage of PIT technology over radio telemetry is clearly that it is relatively less costly permitting higher numbers of individuals to be tagged and there is no limit in the operational life of the transponder. In winter, juvenile salmonids preferred low flow velocity and no preferences were observed for any specific water depth over the range of available water depths. Fish selected preferentially boulder habitat over other substrates in the environment. Habitat utilisation did not differ between day and night. The use of winter preference indices may be important for future habitat modelling.

Conventional and EMG telemetry studies of upstream migration and tailrace attraction of adult Atlantic salmon at a hydroelectric installation on the Exploits River, Newfoundland, Canada

Conventional and electromyogram (EMG) radio telemetry studies have documented occurrence of tailrace attraction and residency, and associated energy cost, for migratory wild Atlantic at a power plant on the Exploits River, insular Newfoundland, Canada. All fish demonstrated some degree of tailrace attraction and turbine discharge was the primary factor resulting in ‘false attraction’. In 2002, residency times were generally less than 1 h, although some fish demonstrated residency between 71 and 118 h. In 2004, after plant refurbishing, fish took from 6 to 11 days to reach the power plant and remained in the tailrace area from 3 to 12 days. Frequent entrances into the tailraces indicated fish were demonstrating a searching behaviour to find the upstream migration route. In 2003 and 2004, EMG data were collected from 3 fish in each year migrating to, and past, the tailraces. An Energy Index was calculated integrating EMG signal and time spent at each location to estimate potential energetic cost. Relatively high-energy expenditure was associated with tailrace attraction and residency in both years. In 2003, fish spent highest energy at the lowest tailrace (first encountered in their migration) while in 2004, there were also high-energy costs associated with a new generating unit. In both years, high EMGs both just below and above the power plant suggested these reaches were arduous and difficult to pass.

Diel activity pattern of juvenile Atlantic salmon (Salmo salar) in early and late winter

Radiotelemetry was used to investigate the diel activity pattern of juvenile Atlantic salmon (Salmo salar) in early and late winter. Fish were active throughout the diel cycle. However, there was significantly less daytime than nighttime movement and movement declined significantly with increasing fork length. Maximizing winter growth rate, through an overall increase in foraging activity, may reduce the risk of starvation in smaller fish. The results of the present study provide evidence that the activity patterns of juvenile salmonids are quite complex and support the suggestion that individual variation in activity patterns are, at least, partially driven by body size.

Activity patterns of juvenile Atlantic cod (Gadus morhua) in Buckley Cove, Newfoundland

We monitored swimming speed of 2–3 year-old juvenile Atlantic cod (Gadus morhua) from August to December 1999, using a 2-D location finding acoustic telemetry system in a coastal area of Newfoundland, Canada. We concurrently monitored the locations of 22–41 individuals by triangulation using a fixed hydrophone array. We estimated average swimming speeds at intervals of 60–120 s and compared them over a 1 to 17 °C thermal range, three diel periods, and five substrates (sand, gravel, sand-sparse boulder, boulder, and kelp). However, cod did not exhibit a change in swimming speed over the temperature range studied. Increased activity and foraging rates (expressed as swimming speeds) were expected to increase at elevated temperatures due to increased metabolic demands. Activity did vary significantly with diel cycle and substrate. Swimming speeds were significantly lower at night during September and October. Results for August and November were inconclusive, while swimming speed was significantly lower during the day in December. We observed significantly reduced average swimming speeds in structurally complex substrates (e.g. rock, cobble and kelp) in September and October. Our results suggest that activity of juvenile cod in the wild does not vary with temperature as predicted from studies in the laboratory. Instead, activity varied with diel cycles and structural complexity, variables that influence an individuals ability to forage and seek refuge, potentially altering individual fitness.

Stream Gradient-Related Movement and Growth of Atlantic Salmon Parr during Winter

Abstract There has been considerable focus on winter studies of Atlantic salmon Salmo salar parr during the last two decades. However, a lack of knowledge exists about the linkage between the physical conditions, including ice, and parr behavior in flow environments during the cold season. In this study, the movement and growth of Atlantic salmon parr were studied during winter in two stream sections with different gradients (0.3% and 1.8%) in a small natural river. Passive integrated transponder (PIT) technology was implemented by using both fixed antennae and mobile tracking devices. In the low-gradient section, the formation of surface ice dominated and created stable conditions, whereas in the high-gradient section, the formation of anchor ice and anchor ice dams occurred periodically and produced a dynamic environment. The results indicated a relationship between parr movement and river gradient. Movement by parr was negatively correlated with time from autumn to late winter but increased as spring a...