D. A. Scruton Æ C. J. Pennell Æ C. E. Bourgeois Æ R. F. Goosney Æ L. King Æ R. K. Booth Æ W. Eddy Æ T. R. Porter Æ L. M. N. Ollerhead Æ K. D.

Transcription

1 Hydrobiologia (2008) 609: DOI /s EIFAC 2006: DAMS, WEIRS AND FISH Hydroelectricity and fish: a synopsis of comprehensive studies of upstream and downstream passage of anadromous wild Atlantic salmon, Salmo salar, on the Exploits River, Canada D. A. Scruton Æ C. J. Pennell Æ C. E. Bourgeois Æ R. F. Goosney Æ L. King Æ R. K. Booth Æ W. Eddy Æ T. R. Porter Æ L. M. N. Ollerhead Æ K. D. Clarke Ó Springer Science+Business Media B.V Abstract Government (Fisheries and Oceans Canada) and industry (Abitibi Consolidated Company of Canada) have been working cooperatively to protect and enhance wild Atlantic salmon populations on the Exploits River, insular Newfoundland, Canada. Since the mid-1960s, enhancement Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries D. A. Scruton C. J. Pennell C. E. Bourgeois R. F. Goosney T. R. Porter L. M. N. Ollerhead K. D. Clarke Fisheries and Oceans Canada, Science Branch, P.O. Box 5667, St. John s, NL, Canada A1C 5X1 D. A. Scruton (&) Sikumiut Environmental Management Ltd, Suite 200, Regatta Plaza, 80 Elizabeth Ave, St. John s, NL, Canada A1A 1W7 Dave.Scruton@Sikumiut.ca L. King Fisheries and Oceans Canada, 4A Bayley Street, Grand Falls-Windsor, NL, Canada A2A 2T5 R. K. Booth Lotek Wireless, 115 Pony Drive, Newmarket, ON, Canada L3Y 7B5 W. Eddy Abitibi Consolidated Inc., P.O. Box 500, Grand Falls-Windsor, NF, Canada A2A 2K1 programmes and construction of fish passage facilities at natural and man-made barriers in the watershed have expanded the range and increased the returning adult population from 1200 fish (circa 1960) to 22,000 fish, on average. Since 1997, attention has been paid to improving passage and survival of downstream migrating smolts and kelts at two hydroelectric facilities at Grand Falls- Windsor and Bishops Falls. At Grand Falls-Windsor a floating louver and bypass system was installed in a power canal and extensive biological, hydraulic, and modelling studies have been conducted to assess, modify, and optimize fish passage. At Bishops Falls, a retrofitted surface spill bypass system was installed in an existing spill gate and similar studies have been conducted to improve passage success. Studies have also been conducted on the upstream migrating adults at these facilities and associated fishways, using conventional and physiological telemetry, to assess tailrace attraction and residency, and the relative energy cost of upstream migration to bypass the hydro plants and fishways. This article reviews the results of these various studies to demonstrate how cooperative work has improved passage of anadromous salmon in coexistence with hydroelectric development. Keywords Hydroelectricity Salmo salar Fish passage Migration Tailrace attraction Newfoundland, Canada

2 226 Hydrobiologia (2008) 609: Introduction Hydroelectricity is an important large scale green energy source. However, hydropower can also have large scale negative environmental effects and during rapid development of hydroelectric potential in Europe and North America in the early 1990s there was little awareness of, and attention paid to, environmental concerns. Hydro development often results in flow alteration (regulation) and dam construction which interrupt the ecological connectivity of riverine systems (Ward, 1989). For anadromous fish, which spend a portion of their life cycle in both fresh and salt water, longitudinal connectivity is critically important allowing migration between spawning, rearing, feeding, and over wintering habitats. Over the last century, increasing emphasis on reducing environmental effects of hydroelectric development has focused attention on provision of fish passage. Initial efforts were largely directed at upstream migration with development of fish ladders, elevators, and transportation systems (Clay, 1995; Larinier, 2001). Over the last 20+ years, there has been increased attention on downstream passage solutions to keep fish out of hydraulic turbines and reduce potential for injury and mortality (Williams et al., 1993; EPRI, 1986; U.S. Congress, 1995). Mortality of Atlantic salmon smolts at dams during downstream migration can adversely affect adult recruitment and yield from the stock originating above the barrier (Ruggles et al., 1993). Smolt descent is a hazardous period in the life history of Atlantic salmon and passage over falls and dams, desmoltification, and predation are major sources of mortality (Hvidsten & Johnsen, 1997). Atlantic salmon adults often over winter in rivers after spawning, returning to the sea as kelts, and these fish can be an important component of the salmon stock as repeat spawners (Porter, 1975). Hence, development of effective downstream fish passage systems at hydro facilities is critical to maintaining Atlantic salmon populations. Site specific studies, in consideration of behaviour and swimming ability of target fish and the structural and operational uniqueness of each hydro plant, are needed to optimize the design and operation, and hence the effectiveness, of fish protection schemes (Coutant, 1999). Upstream migrating Atlantic salmon may travel 1000s of kilometers to reach spawning habitats and, as they do not feed during migration, rely entirely on energy reserves to complete migration, gonad development, and spawning (Lucas & Baras, 2001). At hydro plants, fish are attracted to high water discharge associated with tailraces, which can result in migration delay, injury, increased exposure to predators, higher risk of disease, and environmental stress (Bernatchez & Dodson, 1987; Smith et al., 1997; Winstone et al., 1985). Migration is energetically taxing and impediments to migration can affect migratory distance, ability to reach spawning grounds, and gonadal production; all of which can negatively affect spawning success (Bernatchez & Dodson, 1987). Little is known about the behaviour, swimming strategy, and energetic demands on migrating fish in association with hydroelectric facilities and upstream fish passage systems and recent research has focused on addressing these issues (e.g. Hinch & Rand 1998; Hinch et al. 2002; Scruton et al., 2004b). The Exploits River, insular Newfoundland, Canada, sustains one of the largest populations of anadromous Atlantic salmon (Salmo salar) in North America and two large hydroelectric facilities, with three dams, have been in operation on the river since the early 1900s. Successful enhancement of the salmon population has prompted the hydro company and regulatory agencies to focus on fish passage issues at existing hydro facilities. Refurbishing of existing plants in the 1990s and 2000s provided the opportunity to improve downstream fish passage and two systems were installed; a floating louver behavioural guidance system ( ) and a retrofitted surface spill bypass ( ). Comprehensive studies have been conducted to assess effectiveness of these systems and results have been used to make structural and operational changes to improve overall passage success. Conventional and physiological (electromyogram or EMG) radio telemetry studies have investigated upstream fish passage issues including tailrace attraction, migration delays, and associated energetic costs at the hydro facilities ( ). This article reviews the results of studies to demonstrate how cooperative work has benefited longitudinal connectivity on the Exploits River, improving coexistence of Atlantic salmon with hydroelectricity.

3 Hydrobiologia (2008) 609: Fig. 1 The Exploits River, Newfoundland, Canada showing the location of Bishop s Falls (hydro plant, upstream fishway, surface spill downstream bypass), Grand Falls-Windsor (hydro plant, upstream fishway, floating louver and downstream bypass), and Red Indian Lake (dam and upstream fish elevator) 60 o 49.5 o 52 o 52 o Grand Falls * 46.5 o 60 o o o Study sites The Exploits River, the largest river (11,272 km 2 )on the island of Newfoundland, sustains one of the largest populations of anadromous Atlantic salmon (Salmo salar) in North America (Fig. 1). In the early 1900s, two large hydroelectric facilities, at Bishop s Falls (10 km upstream of the river mouth) and Grand Falls-Windsor (22 km upstream), were constructed to power a pulp and paper mill. Historically, anadromous Atlantic salmon were restricted to the lower 10% of the watershed and fishways were constructed to improve access at Bishop s Falls (1959), Grand Falls (1974), and other locations thereby allowing access to approximately 90% of the watershed. Concurrent with improved access, the salmon stock was enhanced through adult transfers ( ) and fry stocking throughout the drainage ( ) (Taylor & Bauld, 1973; O Connell & Bourgeois, 1987; Bourgeois, 2003; Mullins et al., 2003). The adult salmon population has since increased with adult returns peaking at 32,000 (1996), averaging 22,000 over the last decade (O Connell et al., 2003). Until 1996, water supply to the Grand Falls- Windsor generating facility entered a forebay into penstocks which delivered water to 8 turbines. In 1996, the penstocks and trash racks were replaced with a power canal leading to 2 submerged gates leading to 5 Francis turbines. After power canal construction, a downstream fish protection system, consisting of a floating louver and bypass was installed to pass fish from the canal back into the Exploits River. The system consisted of a floating louver across the canal at an oblique angle to the flow; a bypass channel exiting the canal at the end of the louver line; a fish collection and handling system; and a chute to return fish to the river (Fig. 2). In , additional power generating capacity was installed at Grand Falls-Windsor, which included a new intake and turbine (Beeton unit,

4 228 Hydrobiologia (2008) 609: Fig. 2) and modifications to the dimensions and orientation of the tailraces. Existing generating capacity increased from 45 to 78.5 MW and operation changed from largely a run of river scenario to a run of river with peaking capacity during high flows. Increased flows with additional generation capability and the more perpendicular orientation of tailraces led to concerns of increased tailrace attraction, migration delays, and possible migration (velocity) barriers. In 2002, Abitibi Consolidated Company of Canada (ACCC) upgraded the hydro facility at Bishop s Falls. As part of this upgrading a downstream fish bypass was retrofitted into an existing spillway gate exiting the forebay to reduce entrainment of downstream migrating smolt and kelt into the turbines. The bypass was surface spill type designed to extract water, and migrating fish, directly from the forebay into a plunge pool and then back into the Exploits River, downstream of the dam (Fig. 3). Fishway N 0 100m Beeton unit Flow Power Plant Tailraces Forebay Floating Louver Smolt Bypass Power Canal Fig. 2 A map of the Grand falls-windsor hydroelectric plant including the forebay, power canal, floating louver and bypass, and the newly installed generator (Beeton unit). The location of the Grand Falls fishway is also shown flow Material and methods N 0 100m Spill Gates Forebay Entrance Gates Bypass Forebay Turbine Entrances 0 25m Fig. 3 A schematic diagram of the Bishop Falls hydroelectric plant including the forebay, forebay intake gates, spill gates, surface spill bypass, and turbine entrance Grand Falls-Windsor louver and bypass system Annual monitoring has been conducted to assess effectiveness of the louver and bypass at Grand Falls- Windsor since 1997 (Scruton et al., 2002). The primary objective of this programme has been to assess overall fish guidance efficiency (FGE) for smolts and kelts in relation to hydraulic conditions within the power canal, along the louver, and throughout the bypass. Additional study components have included: residency time in the canal; fish condition; delayed and turbine mortality, and smolt behaviour. A variety of marking and tracking methods have been employed including PIT tagging, external floy tagging and fin clipping, and radio telemetry (stomach and surgical implantation). In addition, release locations (within and upstream of the power plant) and mechanisms have varied and operating conditions (canal and bypass flows, louver angle) have also been modified. Table 1 summarizes the various study parameters and conditions through the 7 years of assessment; the 5 years ( ) of monitoring after initial installation, and 2 years after installation of new generation capacity and alteration of operational regime ( ). Fish guidance efficiency was determined from the ratio (%) of released fish that were detected in the bypass. In 1997, fish bypass efficiency was determined using PIT (passive integrated transponder) tagging and stomach implanted radio fish transmitters (Winter,

5 Hydrobiologia (2008) 609: Table 1 A summary of the fish guidance efficiency (FGE) and ancillary studies conducted at the floating louver and bypass system, Grand Falls-Windsor power canal Year Life stage Method # Trials # Fish Prevailing conditions Pre-Beeton 1997 Smolt PIT tagging Considerable operational problems for louver and Smolt Telemetry 4 61 bypass system Kelt Telemetry and Pit Tagging Smolt Telemetry (sham, control) Louver angle varied, DSP telemetry system used, Smolt Floy tagging 2 97 structural and hydraulic changes to bypass Kelt Telemetry (sham, control) Smolt Telemetry (sham, control) Conditions same as in 1998; louver angle at 12 Kelt Telemetry (control) Smolt Floy Cement abutment removed; modifications to bypass Smolt Telemetry (control) entrance; louver angle at 18, no kelt trials 2001 Smolt Floy Conditions same as in 2000; smolt entrainment into power canal determined; FGEs from floy tag releases only Post-Beeton 2004 Smolt Telemetry 183, 19 1 New release mechanism used; louver array Smolt Floy 597 damaged; test of open system conducted 1 ; kelt canal residency studied 2 ; turbine mortality Kelt Telemetry estimated 2005 Smolt Floy ,40 4 Old release mechanism used; effect of anesthetic Telemetry 9 200, 15 4,60 5 studied 3 ; cycling test conducted 4 ; open test conducted 5 : turbine mortality estimated; strobe light behavioural study conducted 1983). In 1998 and subsequent years, FGE assessments focused more heavily on radio telemetry using digital spectrum processing (DSP) telemetry to track smolt movements through discrete receptions zones along the louver. In 1999, tests were conducted using a 1:25 scaled physical model of the power canal, louver, and bypass at the University of Waterloo, Canada, resulting in a number of recommended physical and hydraulic modifications. Changes in 1999 and 2000 included modifications to the bypass entrance, setting the louver line angle at 18, and removal of a large concrete abutment. In 2000, FGE trials included both radio telemetry and floy tag releases. In 2001, canal and louver conditions were as in 2000 and FGE trials were conducted with floy tag releases only. In 2002 and 2003 there was no FGE monitoring as the power plant was undergoing refurbishing and installation of additional generating capacity (see Study Site description). In 2004 and 2005, monitoring of the louver and bypass system was resumed to study effectiveness under the new operational regime which included peaking power generation during spring flows, increased overall flows and velocities in the power canal, and altered flow patterns within the canal. In 2004 and 2005, smolt and kelt were radio or floy tagged and released to examine FGE, residency and behaviour in the canal, and turbine passage and survival. Bishops Falls surface spill bypass Bypass efficiency has been assessed by releasing experimental groups of smolt and kelt in the Bishops Falls forebay and at an upstream location during peak downstream migration (largely May and June) in (Table 2). Operation of the bypass involved closing the entrance and draining the bypass to enumerate and/or select fish for FGE trials. Fish entering the by-pass were enumerated daily and fish for telemetry studies were removed, moved to a 1000 l insulated container, and transmitters surgically implanted (Adams et al., 1998; Moore et al., 1990). After surgery, fish were transferred to a release-cage

6 230 Hydrobiologia (2008) 609: Table 2 Summary of the radio telemetry trials to assess the effectiveness of the Bishops Falls surface spill bypass for bypassing downstream migrating smolt and kelt in Release location # of trials # fish released Dates Fish size (Mean ± S.E.) 2003 Smolt Forebay June 8 July ± 1.3 Smolt Upstream 1 8 June 28 Kelt N.A. N.A. N.A. N.A Smolt Forebay May 29 July ± 1.3 Kelt Forebay May 28 June ± Smolt Forebay May 29 July ± 0.8 Smolt Upstream 8 64 May 31 June 25 Kelt Forebay 5 40 May 30 June ± 6.7 Kelt Upstream 3 24 June 3 June 19 (forebay or upstream), and released between 17:30 and 20:00 h (varied by year). There was one release location in the forebay in 2003 and 2 (replicate) release cages and in 2004 and Automatic data logging stations were placed throughout the forebay and hydro facility to monitor all possible passage routes; (i) entrance into to the bypass; (ii) turbine entrance; (iii) tailrace (turbine passage); and (iv) across the dam. Residency times, bypass efficiency, and exit routes were determined from data logged on receivers. Another receiver, deployed 1.5 km downstream from Bishop s Falls, monitored radio tagged fish having passed the dam and/or through the turbines. FGEs for smolt and kelt, both forebay and upstream releases, were calculated. The residency time (h) of radio tagged fish in the forebay was evaluated statistically, by passage route (bypassed, turbine passed). The time of day that smolt exited through the bypass or turbines was evaluated with respect to day/night, time of release, and in relation to operation of the bypass. Finally, detection of radio tagged fish at a location downstream of the power plant was used to estimate minimum survival of turbine passage and subsequently passage survival of the hydro facility (all routes combined). Tailrace attraction and energy expenditure of upstream migrants Telemetry studies, using both conventional and electromyogram (EMG) transmitters, have assessed possible tailrace attraction, migration delays, and associated relative energy expenditure below, at, and above the Grand Falls-Windsor hydroelectric facility. Prior to construction of additional generating capacity, conventional radio transmitters were implanted in 25 adult Atlantic salmon in 2002, release below the Grand Falls-Windsor facility, and migration was monitored to and past the power plant with continuously recording receivers to document tailrace attraction and residency times. In 2003, EMG transmitters were implanted in the red (aerobic) swimming muscle adult Atlantic salmon and migration to and past the power plant was monitored to provide an estimate of the relative swimming effort and energetic costs. In both studies, fish were obtained from the Grand Falls fishway, moved to an incubation/holding facility for surgery and recovery, and then released 3 km downstream of the plant. Details on transmitters used, surgical procedures, fish handling and recovery, etc. are in Scruton et al. (2004a, b). It is noteworthy that fish used in tailrace attraction studies were collected from a fishway upstream of the power plant (Grand Falls fishway) consequently the experience of previously having passed the tailraces, either in learning the passage route and/or in energy previously expended, may have influenced the results. However, it was considered that this was a preferable approach to capturing fish from the river, by net or angling, because of the stress that capture may have introduced. Upstream movement of salmon was monitored with data logging stations at 4 distinct locations: (i)

7 Hydrobiologia (2008) 609: two stations downstream of the plant; (ii) one at the tailraces with individual antennae recording presence in separate tailraces; and (iii) a fourth at the Grand Falls fishway. Conventional telemetry data determined presence/absence within the tailrace, length of tailrace residency (h), and subsequent upstream or downstream movement. EMG data determined the number of visits to a particular antenna, time spent, and EMG pulse interval (mean ± SE) for each fish at each location to provide an indication of the relative energy expenditure. A relative energy index (EI) was calculated to estimate the potential energy expended by each fish in association with each antennae location based on the average EMG signal and total time spent (h) at each location, as follows: Energy index ðeiþ ¼ Average EMG ð*10 The total time spent ðhþ Antennae X Þ Antennae X Studies were undertaken in 2004, using both conventional and EMG transmitters, after the installation of the new turbine unit (Beeton), reconfiguration of the power plant tailraces, and under a new operational regime to accommodate additional generation capacity. Conventional transmitters were implanted in 25 adult fish and EMG transmitters were implanted in 3 fish, as previously described. Data logging stations were also as previously described for 2003 with additional antennae added to the Beeton tailrace to more clearly distinguish residency in association with individual tailraces. Results Grand Falls-Windsor louver and bypass system The effectiveness of the system was determined by calculating the FGE (%) or proportion of released fish that used the bypass. Smolt FGEs for the initial assessment after installation ( ) and after installation of additional generation capacity ( ) are provided in Fig. 4. FGEs in the first 2 years of assessment were very low, 23% and 23.4% in 1997 and 1998, respectively, and were linked to unfavourable hydraulic and louver operating conditions. In 1998, the DSP telemetry system and individual receptions zones pinpointed areas where guidance was lost and these were associated with poor louver hydraulic Fig. 4 Fish guidance efficiencies (% ± S.E.) for smolt at the Grand Falls-Windsor floating louver and bypass system. The period from 1997 to 2001 is after initial installation of the system and the period is after installation of additional generation capacity (see text) conditions, in particular large velocity decreases at the entrance to the bypass. Scaled (1:25) physical model tests in 1999 provided evidence of wide fluctuations in velocities in proximity to the louver and throughout the canal in both space and time, with worst hydraulic conditions coincident with locations of greatest loss in smolt guidance. The model tests resulted in changes to improve hydraulic conditions at the bypass entrance and changes in the louver angle, prior to 1999, and removal of an old penstock abutment in the canal was completed prior to In 1999, after the above modifications, studies showed improved hydraulics along the louver line and bypass entrance and a marked increase in the FGEs for both smolts and kelts. Smolt FGEs averaged 54.2% and kelts 46%. In 2000, after removal of the penstock abutment, canal flow patterns improved considerably and smolts FGEs improved to 64.9%. In 2001, after minor changes in fish handling procedures, smolt FGEs were 73.3%, the highest in the initial assessment period ( ). Assessment studies were discontinued in 2002 and 2003, while the Grand Falls-Windsor hydro facility was undergoing modification to increase generation capacity (see Study site ). Studies resumed in 2004 to determine effectiveness of the louver and bypass under the new operating conditions. FGEs for smolts in 2004 declined from previous years, averaging 44.8%, and these were attributed to a decline in

8 232 Hydrobiologia (2008) 609: preferred hydraulic conditions (approach velocities) under the new operational regime, damage to the louver line, and there was concern related to fish handling. Telemetry data revealed both immediate and delayed guidance of smolt with delayed fish demonstrated a cycling behaviour. In 2005, changes in louver operation (water bleed off above bypass entrance; increased flow and acceleration into the bypass) and fish release procedure (fish release cage design) were made with FGEs increasing considerably from 2004, averaging 65.2%. Bishops Falls surface spill bypass FGEs at the Bishops Falls surface spill bypass for forebay released smolt varied from 62.3% (2003) to 71.7% (2004) to 61.7% (2005) (Fig. 5) while FGEs for smolt released upstream of the hydro facility ranged from 75% (1 release, 2003) to 43.7% (8 releases, 2005), and when the FGEs for upstream released fish in 2005 were adjusted (only fish that entered the forebay), FGEs (59%) were similar to forebay releases. Kelt FGEs varied from 92.3% (2004) to 95.9% (2005) while FGEs for upstream released kelts in 2005 were 58.3%, and when adjusted, were 87.5%. Data from a fixed telemetry station downstream of the hydro plant was used to estimate survival of turbine passage and hence overall passage survival (all possible routes). In 2004 and 2005, 44.8% and 45.9% of turbine passed smolt survived resulting in overall project survival of 85.2% and 81.0%, respectively. Conversely, no turbine passed kelt were detected suggesting 100% turbine mortality, however, owing to the high FGEs the overall project survival rates for kelt were high, 93.2% and 95.9% for 2004 and 2005, respectively. The time spent in the forebay by bypassed smolt averaged 39.2, 24.3, and 19.9 h in 2003, 2004, and 2005, respectively, while turbine passed smolt averaged spent 30.0, 57.5, and 30.1 h in 2003, 2004, and 2005, respectively. In 2004 and 2005, forebay residency of turbine passed fish was greater than bypassed fish, and this was significant in 2004 (Mann Whitney Rank Sum Test, P = 0.041), suggesting the longer smolt spend in the forebay the increased likelihood they may be turbine passed. In 2005, the time spent by turbine passed fish was significantly greater for upstream released fish than for forebay released fish (Mann Whitney Rank Sum Test, P = 0.049), suggesting possibly that entering the Fig. 5 Fish guidance efficiencies (% ± S.E.) at the Bishops Falls surface spill bypass system for smolt (upper panel) and kelt (lower panel) from 2003 to 2005 for forebay released fish (black circle), upstream released fish (white circle), and upstream released fish adjusted for those that entered the forebay (grey circle) forebay may result in disorientation, however, FGEs were not significantly different between upstream and forebay released smolt (59.5% vs. 61.7%, respectively). Looking at the time of day that smolt exited the forebay, being bypassed or turbine passed (Fig. 6), it is apparent that most smolt exit after dusk, between 18:00 and 24:00 h, with 62.6, 79.2, and 73.6% of bypassed smolt and 58.3, 54.9, and 69.2% of turbine passed smolt exiting the forebay in this 6 h time window in 2003, 2004, and 2005, respectively. It is also noteworthy that 27.8, 18.4, and 8.3% of the turbine passed fish in 2003, 2004, and 2005 were entrained during 08:00 to 12:00, a period when the bypass was closed for operation and fish had no alternative exit route, suggesting turbine entrainment rates may be biased high and hence the FGEs biased low.

9 Hydrobiologia (2008) 609: Fig. 6 The time of day (24 h clock) that smolt were either bypassed (upper panel) or turbine passed (lower panel). Note the bypass was closed for operation from 08:00 to 12:00 Tailrace attraction and energy expenditure of upstream migrants Twenty-one (21) of 25 conventionally radio tagged adult salmon in 2002 were subsequently detected by the data logging stations at the tailrace area of the Grand Falls-Windsor plant. Fish made both single and multiple entrances into the tailrace area, with two fish having more than 15 tailrace entrances and one with 21 individual entrances (Fig. 7, upper panel).

10 234 Hydrobiologia (2008) 609: Average tailrace residency was min while 4 individuals resided in the tailrace over several days from 24 to 118 h. Tailrace attraction demonstrated two distinct patterns; (i) the most prevalent pattern (n = 17) involving moving in and out of the tailrace over short periods, before proceeding upstream, and (ii) the second pattern (n = 4) involved movement into the tailrace for more extended periods (average residency of 33.4 ± 27.8 h). In 2004, after installation of the increased generation (Beeton Unit) at Grand Falls-Windsor, 30 adult salmon were conventionally tagged and released in four groups. Twentynine were subsequently detected in the tailrace area with most detections associated with unit 4 tailrace, followed by Beeton tailrace, followed by the tailrace for units 5 8. Occurrence of fish in the tailrace for units 5 8 tailrace was important as these units were not operating (no attraction flow), suggesting residency may be related to migration route or physical conditions of the tailrace. Fish in each release took on an average from 6 to 11 days to reach the power plant after release, and remained in the tailrace area for, on an average, from 3 to 12 days (Fig. 7, lower panel). Generally, with each release, the time to arrive at the tailrace increased and the duration in the tailrace area decreased, such that the times to pass the power plant were similar. Three salmon were detected upstream, at the Grand Falls fishway, within 5 days of release suggesting that a component of the migrants undergo rapid upstream migration with minimal attraction and delay. In general, tailrace residency was greater in 2004, post-beeton, than in 2002, suggesting the new operational regime and/or altered tailrace orientation may have contributed to the greater time spent at the tailraces. In 2003, 3 EMG tagged fish released below the Grand Falls power plant were recorded in the vicinity of the power plant and the upstream fishway. EMG data was used to determine the total time spent (h) at various sites (antennae reception zones), average EMG signal at each site, and an energy use index was determined for each location. The 3 fish demonstrated different patterns of migration and tailrace attraction. One fish made repeated visits to the reach below the plant, the tailraces, and above the plant, and, after passing this area, moved quickly and directly to the fishway. The other 2 fish demonstrated fewer visits to the tailraces and a more directed upstream migration. EMG data and the relative EI suggested (a) (b) Fig. 7 Distribution of tailrace entrance attempts by conventionally radio tagged adult Atlantic salmon in 2002 (upper panel). The mean (± S.D.) time from release to arrival at the power plant (lower panel, a) and time spent at the power plant (lower panel, b) for 4 releases of conventionally tagged Atlantic salmon in 2004 differences in relative swimming effort and energy expended by fish at various locations (Fig. 8, upper panel, Fish 32 as an example). High energy expenditure was associated with reaches both below and above the plant, with highest energy expenditure immediately above the plant in a reach that is constricted, turbulent, and high gradient. Energy expenditure was also high at the lowest tailrace (units 5 8) and all three

11 Hydrobiologia (2008) 609: Fig. 8 The time spent (h), average EMG signal, and calculated relative energy index of an EMG tagged fish (Fish #32, 2003, upper panel; Fish #1, 2004, lower panel) in relation to upstream migration below, at, and above the Grand Falls-Windsor power plant and associated tailraces in DS = downstream, TR = power plant tailraces, UP = between the power plant and upstream fishway, and FW = fishway. Antennae 3 is for units 5 8 and antennae 8 and 9 are for the Beeton unit fish spent considerable energy in association with this tailrace, the first they encounter on their upstream migration. In 2004, after installation of the Beeton Unit, 3 EMG tagged fish were also recorded in the vicinity of the power plant and the Grand Falls fishway upstream of the plant. All three fish spent considerable amount of time associated with the lowest tailrace (units 5 8), which were not generating during the study, but was the first tailrace encountered by upstream migrants and conditions (deep, well shaded, no flow) are well-suited for fish holding prior to resuming upstream migration. Fish also spent considerable time in association with the new Beeton unit (antennae 8 and 9), suggesting some delay before passing this tailrace. The relative EI indicated that tailrace residency, particularly at the Beeton unit, were the most energetically costly (Fig. 8, lower panel, Fish #1 as an example). A second fish, demonstrated highest energy expenditure below the plant, related the large amount of time spent at this location (25 h) in comparison with the power plant (41 h distributed between 8 tailrace antennae). The third fish also had high relative energy expenditure associated with the lowest tailrace and Beeton unit. Fish 1 also demonstrated high EMGs at the fishway entrance (antenna 14) and lower reach of the fishway (antenna 15 and 16), however the calculated energy expenditure was low as fish passed these areas very quickly.

12 236 Hydrobiologia (2008) 609: Discussion The louver and bypass system at Grand Falls- Windsor was studied for 5 years after initial installation with emphasis on hydraulic performance and FGE. Louver performance is known to vary in relation to operating hydraulics, fish behaviour, debris accumulation, and other factors (Bates & Vinsonhaler, 1957; Ruggles & Ryan, 1964; Duscharme, 1972; Ruggles et al., 1993) and the initial poor fish guidance (1997/1998) was associated with poor hydraulic conditions along the louver line and entrance to the bypass. Hydraulic conditions at the outset were poor owing to location of the louver line in proximity to the forebay, constricted flow causing turbulence and eddy conditions, and an irregular canal bottom. Tests using a to scale physical model resulted in several physical changes to power canal and fish passage system in 1999/2000 and changes resulted in dramatic improvements to flow patterns in the power canal and continued improvements in FGEs to a high of 73% in An increase in generation capacity in 2002/2003 altered plant operation and hydraulics in the power canal and these changes resulted in poor hydraulics for fish guidance and FGEs in 2004 declined from Three dimensional computer models investigated these problems and a number of physical and hydraulic improvements were implemented, resulting in improved FGEs in Throughout the monitoring of the effectiveness of the fish protection system, the telemetry based assessment was key to linking poor fish guidance with hydraulic problems and subsequent physical and computer based modelling resulted in a number of physical and operating changes to the system which was instrumental in continuous improvement in FGE. The surface spill bypass system at Bishops Falls has been assessed for 3 years and the FGEs for both smolt and kelt have been consistent between years, despite some minor changes in release location, and are within the range of those published for operational hydroelectric facilities. Initially, fish were released from one release cage, considered a possible worst case scenario for smolt entrainment, while in subsequent years 2 cages were used, the second considered more representative of the location of naturally migrating smolt and kelt, however there were no significant differences in FGE between cages in either year. FGEs for kelt were very high, exceeding 92% and 95% in 2004 and 2005, suggesting this surface spill system is very effective for bypassing this life stage. In 2004 and 2005, bypassed fish spent less time in the forebay than turbine passed fish, suggesting that the longer fish reside in the forebay the greater the likelihood they will be turbine entrained. Turbulence in the Bishops Falls forebay can disorient smolt, affect their vertical and horizontal distribution, and as fish swim to maintain position they likely tire and lose the ability to maintain position in the upper water column thereby increasing potential for turbine entrainment. Kelt spent very little time in the forebay (average \2 h), suggesting kelt are very efficient at locating the bypass entrance or, alternatively, kelts are stronger swimmers than smolt (Booth et al., 1997), and may be able to better navigate the turbulent waters of the forebay. In all 3 years, there was a distinct diel pattern in the time of day that fish used bypass and turbine passage routes with most fish exiting between 18:00 and 24:00 h with a clear peak coincident with the onset of dusk (20:00 21:00 h). Timing of passage is consistent with smolt passage at the Grand Falls-Windsor louver and bypass system and with natural smolt migratory behaviour and patterns (Ruggles, 1980; Ruggles & Murray, McCormick et al., 1998; Scruton et al., 2004c). Smolt also spend more time higher in the water column during darkness, likely due to lower predation risk, and this could increase the propensity to find and use the bypass during the dusk and early night hours. Effectiveness of behaviourally based fish protection systems for Atlantic salmon smolts has been evaluated at a number of hydro facilities. Louvers on the East River, Nova Scotia, achieved FGEs of 80% (Duscharme, 1972), while louver systems on the Connecticut River achieved FGEs from 50% to 87% (Ruggles et al., 1993; U.S. Congress, 1995). FGEs achieved at both the Grand Falls-Windsor louver/ bypass and the Bishops Falls surface spill bypass are therefore within the range of those published for operational hydroelectric facilities. Despite physical and hydraulic constraints at Grand Falls-Windsor, continued assessment and modifications to the fish protection system have likely optimized effectiveness under existing logistic and operating conditions. At Bishops Falls, FGEs in the initial 3 years of

13 Hydrobiologia (2008) 609: assessment were also very promising and it is expected that when the bypass becomes fully operational, with increased flow volume into the bypass, the FGEs will continue to improve. In addition, studies at Grand Falls-Windsor and Bishops Falls have determined that passage of these facilities resulted in only a minor disruption in the migration process and have not resulted in any significant migration delay. Atlantic salmon smolt have a limited window where their physiological readiness and environmental conditions are optimal for timing of entry into salt water (Ruggles, 1980; Haro et al., 1998; McCormick et al., 1998) and passage of the hydro facilities on the Exploits River should not affect this timing. Studies on the upstream migration of adult Atlantic salmon have determined the power plant at Grand Falls-Windsor was responsible for some degree of tailrace attraction and, as turbine flow generally represented in excess of 90% of the total discharge passing the facility, the majority of attraction flow encountered by migrating fish was associated with the tailraces. In 2002, two different migratory patterns were observed. However the average residency was short with only 4 of 21 fish demonstrating extended attraction. In 2004, after increasing generating capacity, fish were attracted to main tailraces, including the new (Beeton) unit, however, they also spent considerable time at a tailrace which had no attraction flow, suggesting that migration route and holding characteristics of this location may have influenced tailrace attraction/ residency. Fish spent more time in the tailrace area in 2004, on an average from 3 to 12 days and, as the migratory period progressed, the time to arrive at the tailraces increased and the duration in the tailrace area decreased, such that the times to pass the power plant were similar. Migratory delays in relation to tailrace attraction have been well documented for salmonids in the Pacific Northwest (e.g. FERC, 1995), Scotland (e.g., Gowans et al., 1999, 2003) and Norway (e.g. Thorstad et al., 2003; Fleming and Reynolds, 1991) and delays can affect fish spawning depending on a location of spawning sites, difficulty of the remaining migration, energy consumed, maturity, and environmental conditions. In our studies, salmon were attracted to the tailraces for an average of 33.4 h (2002) and 3 12 days (2004), and these delays are considerably less than those reported in the literature and considered not of an extent to affect reproductive success. Physiological (EMG) telemetry was used to provide insight into migratory behaviour, and relative energetic costs of migration and a relative energy index was used to integrate both the swimming effort, inferred from EMG data and time spent in relation to this effort. There was relatively high energy expenditure associated with tailrace attraction and residency in the 2 years of study and the pattern in energy expenditure were similar in fish in each year. In 2003, fish spent highest energy at the lowest tailrace (first encountered) in their migration. In 2004, there were also high apparent energy costs at this location but highest energy costs were associated with the new Beeton unit. There was also apparent energy expenditure both immediately above and below the power plant. River reaches with relatively complex hydraulics, high gradient, and associated high velocities can also be difficult points of passage (Hinch & Brattey, 2000; Hinch et al., 2002; Standen et al., 2002), and high EMGs below and above the power plant suggested these reaches, being constricted, high gradient, and turbulent, were arduous and difficult to pass. It is also important to note that swimming in high velocity, turbulent reaches can be fuelled by anaerobic metabolism and EMG data may therefore underestimate true energy expenditure (Cooke et al., 2004). Conclusions A continual challenge for industry and government is to minimize potential negative impacts of hydro development on anadromous fish populations and this is particularly difficult for installations that have been constructed and operated for close to 100 years. A floating louver and bypass system in the power canal at Grand Falls-Windsor has undergone considerable assessment and modification to optimize effectiveness. A surface spill type fish bypass, in a forebay spill gate at the Bishops Falls, is undergoing similar assessment to improve fish passage and survival. These two downstream fish passage systems represent both ends of a spectrum in fish passage technology with the floating louver and fish bypass being a highly engineered system while the surface spill bypass system is a relatively simple retrofit

14 238 Hydrobiologia (2008) 609: solution. Both systems demonstrate that retrofit solutions can be found to improve downstream fish passage conditions at existing power plants and biological and hydrological studies are important to improve effectiveness of these systems. Our studies have determined upstream migrating adult Atlantic salmon experience some degree of tailrace attraction and migration delay at the Grand Falls-Windsor facility and physiological telemetry indicated energy expenditure associated with attraction to tailraces, however, there was comparable energy expenditure associated with natural reaches above and below the power plant. Migration delays and energetic costs associated with this facility, in the context of the overall migratory challenges facing salmon on the Exploits River, were not considered to be of sufficient magnitude to be important in migratory or reproductive success. Implementation of retrofitted downstream fish bypass solutions and study of the challenges facing upstream migrating salmon is a good example of industry (Abitibi Consolidated Company of Canada) and government (Canadian Department of Fisheries and Oceans) working cooperatively to resolve address fish passage issues at hydroelectric facilities on the Exploits River. The Exploits River is a classic example of development of a large self sustaining wild salmon population, through enhancement and opening up habitat, and all interested parties working to enhance coexistence of hydro and salmon. References Adams, N. S., D. W. Rondonf, S.D Evans, J. E. Kelly & R. W. Perry, Effects of surgically and gastrically implanted radio transmitters on swimming performance and predator avoidance of juvenile chinook salmon (Oncorhynchus tshawytscha). Canadian Journal of Fisheries and Aquatic Sciences 55: Bates, D. W. & R. Vinsonhaler, Use of louvers for guiding fish. 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