Alouette Water Use Plan

Transcription

1 Alouette Water Use Plan Kokanee Out-Migration ALUMON#2 Study Period: 2009 Report Date: February 2010 LGL Environmental Research Ltd. February 2010

2 EA 3071 Evaluation of the Migration success of O. nerka (Kokanee /Sockeye) from the Alouette Reservoir, 2009 Prepared for: BC Hydro Water License Requirements 6911 Southpoint Drive, E16 Burnaby, BC V3N 4X8 Prepared by: M. A. Mathews and R. C. Bocking LGL Limited environmental research associates 9768 Second Street Sidney, British Columbia, V8L 3Y8 February 2010

3 EVALUATION OF THE MIGRATION SUCCESS OF O. nerka (KOKANEE / SOCKEYE) FROM THE ALOUETTE RESERVOIR, 2009 Prepared by: M. A. Mathews and R. C. Bocking LGL Limited environmental research associates 9768 Second Street, Sidney, BC V8L 3Y8 Prepared for: BC Hydro Water License Requirements 6911 Southpoint Drive, E16 Burnaby, BC V3N 4X8 28 February 2010

4 EXECUTIVE SUMMARY In order to assess the feasibility of sockeye re-introduction into the Alouette reservoir, studies are being conducted to determine the volitional migration success of O. nerka (Oncorhynchus nerka) from the reservoir. This was the fifth year of study of juvenile salmon migration from the Alouette reservoir. In 2005, spillway releases at the Alouette Dam occurred from 3 May to 3 June to evaluate the migration success of marked coho smolts as they were captured in the Mud Creek rotary screw trap. In 2006, spillway releases at the Alouette Dam again occurred from 11 to 31 May to evaluate the migration success of marked steelhead from the reservoir. In both years coincidental O. nerka emigrations were also monitored and an estimated 7,900 and 5,064 O. nerka smolts migrated from the reservoir respectively. In 2007, O. nerka smolts again migrated from the reservoir during spillway releases. A total of 7,787 were captured during the monitored period of 16 April to 6 June, resulting in a mark-recapture estimate of 62,923 (48,436 77,410; 95% CL) using a pooled Peterson method. In the 2008 study, a total of 3,224 O. nerka were captured as they migrated from the reservoir from 15 April to 26 May. A mark-recapture estimate of 7,712 (6,682 8,742; 95% CL) was determined using a pooled Peterson method for the period of 21 April to 8 May; based on a trap efficiency of 40.3%, an additional 545 O. nerka are estimated to have migrated prior and subsequent to that period. In total 8,257 O. nerka were estimated to have migrated from the Alouette reservoir in In 2009, 1,247 O. nerka were captured at Mud Creek as they migrated from the reservoir and a pooled Peterson mark recapture estimate of 4,287 (3,833 4,741; 95% CL) was calculated for the period of 21 April to 28 May (trap efficiency of 33.5%). Spillway gate flows were maintained between 3.2 and 4.3 m 3 /s from 15 April to 15 June, comparable to the flows maintained during the 2007 and 2008 smolt migrations. This was the first year of a post-surface release flush, scheduled for seven days at the tail end of the migration, however once flows reached a maximum of 6.5 m 3 /s the integrity of the rotary screw trap and safety of crew and captured fish became a concern and the flush had to be terminated after only three days. No increases in catch were associated with the flushing flows. In addition to monitoring O. nerka migrations, all other species captured were enumerated. This included monitoring steelhead captures for marks applied in the 2006 project (adipose fin clips and/or red visible implant elastomer tags). Four adipose clipped steelhead were captured; these fish were either large, residualized smolts from the 2006 project, or fish from reservoir stocking that occurred in 2007 and An additional 467 wild or unmarked steelhead smolts were enumerated. In 2009, a total of 45 adult sockeye returned to the dam at the outlet of the Alouette reservoir. Of the 43 fish released in the reservoir, 15 sockeye were tagged and tracked with radio telemetry to help determine the spawning location and timing of the returns (Plate and Bocking 2010). During the summers of 2007 and 2008, a total of 28 and 54 adult sockeye returned to the dam at the outlet of the Alouette reservoir, respectively. In 2007, six sockeye were transported up and released into the reservoir while in 2008, 53 adult sockeye were released into the reservoir. Genetic analysis and biosampling results of the 2009 adult sockeye returns are discussed in Cruickshank (2010). LGL Limited / Katzie Page i

5 TABLE OF CONTENTS EXECUTIVE SUMMARY...I LIST OF TABLES... III LIST OF FIGURES... III LIST OF APPENDICES... III LIST OF PHOTO PLATES...IV INTRODUCTION... 1 Management Questions... 2 Specific Objectives for METHODS... 4 Alouette Reservoir Study Area... 4 BC Hydro Operations... 5 Fish Captures... 5 RESULTS... 8 BC Hydro Operations... 8 Rotary Screw Trap Operations and Physical Conditions Fish Captures O. nerka O. nerka Bio Sampling Steelhead Smolts Other Species DISCUSSION BC Hydro Operations Mud Creek Trap Operations O. nerka Steelhead Smolts Adult Sockeye Returns RECOMMENDATIONS ACKNOWLEDGMENTS LITERATURE CITED APPENDICES LGL Limited / Katzie Page ii

6 LIST OF TABLES Table 1. Hydro operations at the Alouette reservoir during the 2009 study period Table 2. Daily catch of O. nerka in the Mud Creek and 216th Street RSTs, Table 3. Total catch at the Mud Creek RST and corresponding population estimate of O. nerka migrating from the Alouette Reservoir, 2005 to Table 4. Mean fork length of O. nerka less than 100 mm ( )...17 LIST OF FIGURES Figure 1. Map of Alouette watershed showing local communities and features... 4 Figure 2. Map of South Alouette River and locations of rotary screw traps (figure provided by Westslope Fisheries Ltd) Figure 3. Comparison of spillway gate flows during the O. nerka migration period, Figure daily discharge (m 3 /sec) for Water Survey of Canada Station No. 08MH005 located on the mainstem South Alouette River at the 232nd Street bridge (figure from Water Survey of Canada website: 12 Figure 5. Daily catch of O. nerka at the Mud Creek RST in 2009 in comparison to the previous four years (spillway opened 3 May, 11 May, 16 April, 15 April and 15 April for 2005, 2006, 2007, 2008 and 2009, respectively) Figure 6. Length frequency of O. nerka captured in the Mud Creek RST operated in the South Alouette River, Figure 7. Length-weight relationship of the O. nerka smolts migrating from the Alouette reservoir, Figure 8. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2006) Figure 9. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2007) Figure 10. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2008) Figure 11. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2009) LIST OF APPENDICES Appendix A. Physical data at the Mud Creek rotary screw trap site, Appendix B. Catch of non-target species at Mud Creek RST, Alouette River, LGL Limited / Katzie Page iii

7 LIST OF PHOTO PLATES Photo 1. Mud Creek RST used to capture O. nerka migrating from the Alouette reservoir, Photo 2. An example of the daily mixed species catch at the Mud Creek RST, Photo 3. Biosampling gear at the Mud Creek RST, Photo 4. The Mud Creek RST fishing during typical flows of the 2009 smolt migration (from 3.2 to 4.3 m3/s ) Photo 5. The Mud Creek RST fishing during the 2009 post-surface release flush period Photo 6. Daily sampling at the Mud Creek RST, Photo 7. Large catch of chum fry in the Mud Creek RST, LGL Limited / Katzie Page iv

8 INTRODUCTION Numerous interested parties in the Alouette Watershed, including government agencies, the Katzie First Nation, stewardship groups, environmental Non-Government Organizations (NGOs), and concerned citizens have a vision of restoring historic salmon runs above the Alouette Dam at the outlet of the Alouette reservoir. Salmon re-introduction to the Alouette reservoir hinges on determining whether or not juvenile salmonids (smolts) will exit over the dam at the south end of Alouette reservoir or through the diversion to Stave Lake at the north end of Alouette reservoir. A previous feasibility assessment on fish passage by Bengeyfield et al. (2001) suggested that the majority of out-migrating smolts would orient to the much higher diversion flows in watersheds with inter-basin water transfers (Alouette, Coquitlam and Carpenter). As a consequence, Bengeyfield et al. (2001) believed there was a reduced likelihood of successful re-introduction of anadromous salmonids above dams in these watersheds. In 2002, LGL Limited developed a framework for evaluating fish passage issues in the Bridge Coastal hydro operating area (Bocking and Gaboury 2002). Following this, the BCRP sponsored an evaluation of the feasibility of restoring anadromous fish passage into the Alouette reservoir (Gaboury and Bocking 2004). Numerous recommendations were made for future studies to address the fish passage question at Alouette reservoir. To address the issue of whether smolts would exit over the dam or the diversion to Stave Lake, the BCRP sponsored a study in 2005 that monitored the migration of coho smolts out of the Alouette reservoir and down the South Alouette River using unique colours of visible implant elastomer tags during a test surface release of ~ 3 m 3 /s from the Alouette Dam (Baxter and Bocking 2006). Estimated migration success rates of coho smolt to the Lower Alouette River ranged from 79% for smolts released at the spillway to 31% - 38% for smolts released in the reservoir. The 2005 study also monitored the migration of acoustic transmitter- tagged sockeye / kokanee or O. nerka (raised to a suitable size) for subsequent detection in listening arrays in the lower Fraser, Juan de Fuca Strait, and Strait of Georgia. Estimated migration success from the release location was 26% to the lower Fraser detection array and 5.3% to the Juan de Fuca detection array. In 2005, an estimated 7,900 O. nerka also emigrated from the reservoir. This unexpected result prompted the Water Use Plan Consultative Committee (WUP CC) to recommend the surface release be done annually. In 2006, a study was conducted to monitor steelhead smolt migration success out of the Alouette reservoir and down the South Alouette River using both visible implant elastomer tags and adipose fin clips (Humble et al. 2006). The estimated migration success rate to the Lower Alouette River was only 5.8% for steelhead smolts released in the reservoir. This low rate was believed to be, at least in part, related to the delayed opening of the spillway gate due to low water levels in the reservoir. The 2006 project also provided a second year of O. nerka passage with an estimated 5,064 O. nerka migrating from the reservoir during the surface release flow of ~ 3 m 3 /s. The 2005 and 2006 study results indicated that O. nerka were successfully migrating from the Alouette reservoir and suggested the potential for adult sockeye returns as early as In order to begin assessing the feasibility of sockeye re-introduction into the Alouette reservoir, the 2007 smolt study was conducted to determine the volitional migration success of O. nerka from the reservoir during the surface release flow of ~ 3 m 3 /s. In 2007, a total of 7,787 O. nerka were captured in the Mud Creek rotary screw trap (located 1.5 km downstream of the dam) as they LGL Limited / Katzie Page 1

9 migrated, yielding a total estimate of 62,923 (48,436 77,410; 95% CL) O. nerka that emigrated from the Alouette reservoir (Mathews and Bocking 2007). Supported by the previous three years of results and as part of the Water Use Plan, the surface release flow was planned to continue annually with the expectation of re-establishing a sockeye run. As monitoring continued in 2008, a total of 3,224 O.nerka were captured at Mud Creek from 15 April to 26 May. The total 2008 migration was estimated to be 8,257 fish and included a mark-recapture estimate of 7,712 (6,682 8,742; 95% CL) from 21 April to 8 May and an additional 545 migrants based on trap efficiency outside of the marking period (Mathews and Bocking 2009). In the summer of 2007, 28 adult sockeye returned to the Alouette River; DNA and scale sample analysis indicated these fish were from the 2005 O. nerka smolt emigration from the reservoir. During the summer of 2008, 54 adult sockeye returned to the Alouette River and genetic analysis indicated no discernable difference between these returning adults and the O. nerka smolt migrants (Mathews and Bocking 2009). These two years of returns, along with the continued smolt migration, lend support to the expectation that an Alouette River sockeye run, extirpated since the mid 1920s following the impoundment of the reservoir, could be re-established. Since 2008, as part of the Water Use Plan, the surface release flow from the Alouette Dam is planned to continue annually with the expectation of re-establishing a sockeye run. Due to run timing uncertainty, it has been proposed that the surface release be done for a period of 8 weeks and annual monitoring of the migration should continue to identify the typical start, duration and peak in hopes of shortening the duration of the release and reducing the corresponding flood risks. Although the migration timing has remained relatively consistent during the two years of full season monitoring, the 2008 migration finished earlier than the 2007 migration and the 2008 peak catch did not correspond to peaks in spillway flow, hence subsequent years of monitoring are needed to help to improve the understanding of the timing of the run. To address the uncertainty of whether the current magnitude of release is sufficient to promote migration among all seaward smolts, an experimental post-surface release flush was proposed for every second year of monitoring to determine if a doubling of flows for 7 days could induce additional migrants to move out of the reservoir. Management Questions Three management questions are to be addressed throughout the subsequent years of monitoring: 1. Is the surface release of at least 3 m 3 /s from the Alouette Dam (obtained through the spillway gate) adequate to promote the downstream migration of O. nerka smolts out of the Alouette Reservoir? To address Question 1, the following hypothesis will be tested: H O 1: The seaward movement of kokanee smolts, as identified from rotary screw trap data collected at the confluence of Mud Creek, has a start, peak and end that is characteristic of kokanee/sockeye smolts found in other systems (e.g. Cultus Lake sockeye) LGL Limited / Katzie Page 2

10 2. Does a post-surface release flush of 6-9 m 3 /s, lasting 7 days following the tail end of the out migration period, encourage more smolts to leave the system? To address Question 2, the following hypothesis will be tested: H O 2: The seaward movement of kokanee smolts, as identified from rotary screw trap data collected at the confluence of Mud Creek, has a start, peak and end (i.e., a bimodal out migration pattern) during those years when a post-surface release flush of 6-9 m 3 /s is implemented (the post surface release flush will be implemented on average every two years). 3. How long should the surface release last to ensure out migration of all smolts prepared to leave the system? This question will be addressed through consideration of the results of the two hypotheses identified above, the start, peak and end dates of the migration period, the duration of the surface release, the results of the downstream movement pattern assessment and the smolt out-migration data of other coastal systems. This result will then form the basis for an alternative surface release regime to be considered at the next WUP review in Specific Objectives for 2009 The specific objectives for the 2009 study year were: 1. BC Hydro to operate the Alouette Dam spillway to allow ~ 3.0 m 3 /s of flow from 15 April to 15 June 2009, including a post-surface release flush of 6-9 m 3 /s, lasting 7 days following the tail end of the out migration period. Flows through the low level outlet will be held near 0.0 m 3 /s for the study period; 2. Install and operate a rotary screw trap (RST) at the Mud Creek site, located 1.5 km downstream of the Alouette Dam, from 15 April to 15 June 2009 to monitor the migration of O. nerka from the reservoir; 3. Capture O. nerka from the Alouette reservoir in the Mud Creek RST; 4. Mark every second O. nerka captured (lower caudal-clip) throughout the entire migration and re-capture these same marked O. nerka in the Mud Creek RST to estimate total emigration; 5. Determine the abundance, timing and biological characteristics of O. nerka migrating from the Alouette reservoir; 6. Collect genetic tissue from 100 individuals of O. nerka to determine stock identification; 7. Monitor the potential continued migration of steelhead released in 2006 from the Alouette River and reservoir; and 8. Record incidental catches of all other species. LGL Limited / Katzie Page 3

11 METHODS Alouette Reservoir Study Area The Alouette reservoir is located in east Maple Ridge in southwest British Columbia (Figure 1). The South Alouette River watershed is a relatively small system (144 km 2 ) that arises in the Coastal Mountains of Golden Ears Provincial Park, approximately 50 km northeast of Vancouver, BC. The upper watershed flows into an impounded reservoir known as Alouette Lake. At the reservoir s river outlet, the South Alouette River flows for 21 km before entering Pitt River near Pitt Meadows and the Pitt River, in turn, flows south into the Fraser River at Douglas Island. Present fish resources within the Alouette reservoir include kokanee (Oncorhynchus nerka), rainbow trout (O. mykiss), bridge-lip sucker (Catostomus columbianus), bull trout (Salvelinus confluentus), cutthroat trout (O. clarki clarki), lake trout (Salvelinus namaycush), stickleback (Gasterosteus sp.), sculpin (Cottus sp.), northern pike minnow (Ptycheilus oregonensis), peamouth chub (Mylocheilus caurinus), large scale sucker (Catostomus macrocheilus), and red side shiner (Richardsonius balteatus); (Wilson et al. 2003). Figure 1. Map of Alouette watershed showing local communities and features. LGL Limited / Katzie Page 4

12 BC Hydro Operations To facilitate the 2009 study, BC Hydro agreed to release water from the Alouette Dam, over the spillway while closing the low level outlet for the period of 15 April to 15 June. This was the first year of the post-surface release flush which began on 25 May but was terminated early on 27 May due to safety concerns for both the sampling crew and fish captured and the integrity of the rotary screw trap. With the exception of increased flows during the flush period the spillway release and low level closure were consistent throughout the duration of the RST operation. Fish Captures Rotary screw traps (RSTs) located approximately 1.5 and 16 km downstream of the Alouette Dam were used to capture all migrating salmonids with the primary focus of this study being the trap at Mud Creek (Photo 1), 1.5 km below the dam (Figure 2). The RST at the 216 th Street location, 16 km downstream, was operated by Westslope Fisheries Ltd. The Mud Creek trap was checked daily in the morning and trap checks consisted of enumerating all species of fish within the holding box (Photo 2). Unmarked fish were enumerated to species and released downstream of the trap. All steelhead were examined for adipose fin clips (clipped in 2006) and if clipped were also examined for the presence of a fluorescent VIE tag prior to their release downstream. Photo 1. Mud Creek RST used to capture O. nerka migrating from the Alouette reservoir, LGL Limited / Katzie Page 5

13 Figure 2. Map of South Alouette River and locations of rotary screw traps (figure provided by Westslope Fisheries Ltd). Photo 2. An example of the daily mixed species catch at the Mud Creek RST, LGL Limited / Katzie Page 6

14 A pooled (unstratified) Peterson estimate was used to estimate the number of emigrating O. nerka from the reservoir from 21 April to 1 June. This estimated period included the first potential date of recaptures until the last date of smolts captured. The approximately unbiased estimate of the population size using a pooled Peterson estimator with a Chapman modification includes the following statistics: (1) N ( M 1)( C 1) 1 R 1 where, C= total number of fish caught in second sample (including recaptures), M= number of fish caught, marked and released in first sample, N= population estimate, R= number of recaptures in the second sample (fish marked and released in the first sample). An approximately unbiased estimate of the variance of the stratum population is: Variance of ( M 1)( C 1)( M R)( C R) N (2) 2 ( R 1) ( R 2) Standard error is calculated as: Standard error= Varianceof N (3) An approximate 95% confidence interval for N is: N ± 1.96 * Standard error (4) Marking was conducted by lower caudal clipping every second fish captured throughout the operating period for a total of 583 O. nerka from the Mud Creek RST catch. All marked fish were released into the plunge pool below the dam. A total of 501 O. nerka captured at the Mud Creek RST were sampled for fork length and weight. Any fish >100 mm were targeted for sampling (12 fish) while fish <100 mm were randomly sampled. Of the 501 fish sampled for length and weight, scale samples were collected from 301 smolts (to determine age) over the course of the project. Additional genetic samples (fin tissue clips) were collected from 100 of these smolts to be processed for stock identification at the Pacific Biological Station (Photo 3). LGL Limited / Katzie Page 7

15 Photo 3. Biosampling gear at the Mud Creek RST, RESULTS BC Hydro Operations The Alouette Dam spillway gate was opened on 15 April, and with the exception of the postsurface release flush period, flows were maintained between 3.2 and 4.3 m 3 /s (Photo 4). Gate openings ranged from 0.12 to 0.3 m until closed 16 June (Table 1). The flush period began 25 May and was scheduled to occur for seven days. Maximum flows reached 6.5 m 3 /s (Photo 5). The high flows proved too much to operate the RST safely for both the crew and fish captured and the integrity of the trap was threatened. Therefore, the flush was terminated on 27 May. Spillway flows in 2009 were similar to those maintained in 2007 and 2008, although this was the first year of the post-surface release flush during the migration period. Again in 2009, spillway flows were consistently greater than the 2005 and 2006 flows which were generally maintained between 2.5 to 3.0 m 3 /s (with the exception of a spike in mid May of 2006) (Figure 3). Power was generated from the turbines at the Alouette Powerhouse on the shore of Stave Lake from 16 April to 10 June. Flow did not occur through the low level outlet at Alouette Dam once the opening was closed on 15 April until reopened on 16 June. LGL Limited / Katzie Page 8

16 Photo 4. The Mud Creek RST fishing during typical flows of the 2009 smolt migration. Photo 5. The Mud Creek RST fishing during the 2009 post-surface release flush period. LGL Limited / Katzie Page 9

17 Table 1. Hydro operations at the Alouette reservoir during the 2009 study period. Daily Average Daily Average Daily Average Daily Average Low Level Low Level Power Reservoir Spillway Gate Spillway Gate Outlet Outlet Flow Generation Date Elevation (m) Opening (m) Flow (m 3 /sec) Opening (m) (m 3 /sec) (MegaWatts / hour) 15-Apr at 10:56 to settle at 0.17 at 11: at 10:58 to settle at 0 at 11: Apr Apr Apr Apr Apr Apr Apr closed to 0.14 at 9: Apr Apr Apr Apr Apr Apr Apr opened to 0.3 at 9:55 then settled at 0.15 at 9: Apr May May May May May May May May May May May May May closed to 0.12 at 13: May May May May May May May May May May May May opened to 0.16 at 12:39 then settled at 0.25 at 12: May May closed to 0.21 at 11:18 then settled at 0.13 at 12: May May May May Jun Jun Jun Jun Jun opened to 0.14 at 12: Jun Jun Jun Jun opened to 0.17 at 13: Jun closed to 0.15 at 9: Jun Jun Jun Jun Jun Jun closed to 0.14 at 9:52 then settled at 0 at 13: at 13:12 to settle at 0.85 at 13: LGL Limited / Katzie Page 10

18 Spillway Gate Flow (m 3 /sec) Apr 20- Apr 25- Apr 30- Apr 5- May 10- May 15- May 20- May 25- May 30- May 4- Jun Figure 3. Comparison of spillway gate flows during the O. nerka migration period, Rotary Screw Trap Operations and Physical Conditions The Mud Creek rotary screw trap was operated consistently from 15 April to 1 June. Although spillway flows continued as planned until 15 June, monitoring ceased on 1 June once daily catches diminished and it was believed the migration had finished. The trap at the 216 th Street location operated from 15 April to 15 June however a few inconsistencies occurred: 1) 6 May to 7 May the RST was fished inconsistently and the catch was not enumerated to allow the passage of a release of hatchery Chinook fry 2) 6 June the trap was jammed and the catch was lost and 3) 29 May to 14 June the trap was not fished during daylight when staff were not present on site due to increased volume of recreational users on the water. The latter is not believed to be an issue as observations from previous years document smolts are very rarely captured during daylight unless there is a storm event and hence a turbidity and flow pulse, if this occurs recreational users are not on the water and the trap is fished (Scott Cope, pers. comm.). Water temperature, RST revolutions per minute (RPM), daily water levels and general weather conditions were recorded daily during the study from 16 April to 1 June at the Mud Creek site (Appendix A). Daily discharge for Water Survey of Canada Station No. 08MH005, located on the mainstem South Alouette River, is presented in Figure 4. The spillway flushing flows in late May did correspond to an increase in discharge however there was no increase in spillway flow corresponding to the spike in discharge that occurred around 4 May (Table 1, Figure 4). LGL Limited / Katzie Page 11

19 Figure daily discharge (m 3 /sec) for Water Survey of Canada Station No. 08MH005 located on the mainstem South Alouette River at the 232nd Street bridge (figure from Water Survey of Canada website: Fish Captures O. nerka During the 2009 migration, 1,247 O.nerka were captured in the Mud Creek RST (Photo 6, Table 2). Peak catch occurred on 18 May (n=246) and there were no increases in catch during the flushing flow period of 25, 26 and 27 May (n=15, 10 and 6 respectively). Recaptures of 195 of 583 marked O. nerka released below the dam resulted in a total estimate of 4,287 (3,833 4,741; 95% CL) smolts migrating from the Alouette reservoir in 2009 (mark/recap period of 21 April to 1 June). This 2009 migration is the smallest estimated since monitoring began in The 2009 estimate is only half that of the 2008 estimate of 8,257, substantially less than the 2007 estimate of 62,923 (48,436 77,410; 95% CL), and even less than the 2006 and 2005 estimates of 5,064 and 7,900 respectively, which were incomplete estimates as the spillway opening was delayed until after the migrations had started (Table 3). The 2009 trap efficiency of 33% is comparable to previous years with the exception of 2007 (12%). The daily catches of O. nerka at the Mud Creek RST in 2009 as compared to the previous four years are shown in Figure 5; the 2009 catch is the lowest recorded since monitoring began in The 2009 run timing follows a similar trend of duration as previous years, beginning mid April and tapering off at the end of May; the 2009, 2007 and 2006 migrations continued approximately an additional week after the 2008 and 2005 migrations tapered off. The peak in 2009 occurred in the latter half of May while the 2007 and 2008 peaks both occurred late April. The 2005 and 2006 migrations are not comparable as the spillway was opened late (3 May and 11 May respectively) in those years. LGL Limited / Katzie Page 12

20 Photo 6. Daily sampling at the Mud Creek RST, A total of 121 O. nerka were captured in the trap at the 216 th Street location 16 km below the dam, seven of which were caudal clipped recaptures marked at the Mud Creek trap (Cope 2010). Peak catch occurred on 19 May (n=35), one day after the Mud Creek peak catch. As was the case with the Mud Creek trap, there were no increases in catch during the flush period. A complete summary of rotary trap operations and fish captures at the trap at the 216 th Street location can be found in Cope (2010). LGL Limited / Katzie Page 13

21 Table 2. Daily catch of O. nerka in the Mud Creek and 216 th Street RSTs, Daily Total Date Mud Creek 216 th St unmarked clip recaptures unmarked clip recaptures 15-Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr May May May May May May May May May May May May May May May May May May May May May May May May May May May May May May May Jun Totals 1, O. nerka Passage at Mud Creek: No. O.nerka clipped and released below dam 583 O. nerka recaps 195 Estimated O. nerka passage (21 April to 1 June) 4,287 95% Confidence Limits 3,833-4,741 Trap efficiency 33.5% LGL Limited / Katzie Page 14

22 Table 3. Total catch at the Mud Creek RST and corresponding population estimate of O. nerka migrating from the Alouette reservoir, 2005 to Year Total Catch Estimate 95% Confidence Intervals Trap Efficiency Method ,310 7,900 n/a 42% Based on coho trap efficiency (Baxter and Bocking 2006) ,757 5,064 n/a 35% Based on O. nerka trap efficiency (Humble et al. 2006) ,787 62,923 48,436-77,410 12% Pooled Peterson estimate: 19 April to 1 June (Mathews and Bocking 2007) Pooled Peterson estimate (21 April to 8 May) = 7,712 (6,682-8,742; 95%CL) + Trap efficiency ,224 8, % estimate (15 April to 20 April & 9 May to 26 May) = 545 (Mathews and Bocking 2009) ,247 4,287 3,833-4,741 33% Pooled Peterson estimate: 20 April to 1 June (Mathews and Bocking 2010) 1400 Number of O. nerka Captured : n = 3, : n = 1, : n = 7, : n = 3, : n = 1, Apr 20-Apr 25-Apr 30-Apr 5-May 10-May 15-May 20-May 25-May 30-May 4-Jun Figure 5. Daily catch of O. nerka at the Mud Creek RST in 2009 in comparison to the previous four years (spillway opened 3 May, 11 May, 16 April, 15 April and 15 April for 2005, 2006, 2007, 2008 and 2009, respectively). LGL Limited / Katzie Page 15

23 O. nerka Bio Sampling Biosampling results from the 501 O. nerka sampled for length and weight at the Mud Creek RST revealed that the sockeye smolts were most abundant in the mm length classes (n=203). This differed from the previous four years as the most abundant length classes sampled in 2005 and 2006 were mm, mm in 2007 and in 2008 (Figure 6). Of the 501 migrants measured, 12 fish were >100 mm and therefore targeted for age and size sampling. The weights of the 501 migrants sampled ranged from 1.2 to 60.5 grams, with a mean of 4.0 grams. A length weight relationship with a fitted regression line is displayed in Figure 7 (r 2 =0.98). Of those O. nerka less than 100 mm in length (and considered to have over-wintered one year in the reservoir), differences in fork length were statistically significant among the years (F=157.5, P<0.0001). The 2005 and 2006 mean fork lengths (78.6 and 79.4 respectively) were not significantly different between those specific years, neither were the 2006 and 2007 mean fork lengths (79.4 and 80.8 respectively), however the mean fork lengths from all other year combinations differed from one another, including the 2008 and 2009 mean fork lengths (71.2 and 75.0 respectively) (Table 4) : n = : n = : n = : n = : n = 501 Number of O. nerka Fork Length (mm) Figure 6. Length frequency of O. nerka captured in the Mud Creek RST operated in the South Alouette River, LGL Limited / Katzie Page 16

24 80 70 y=(9.49e-06)x+( ) r2= Weight (g) Fork length ^3 (mm) Figure 7. Length-weight relationship of the O. nerka smolts migrating from the Alouette reservoir, The 301 scale samples collected for age analysis in 2009 have been sent to the Pacific Salmon Commission to be processed at a later date; hence age results are not included in this report. The 100 fin tissue clips collected for genetic analysis were processed for stock identification at the Pacific Biological Station and the results can be found in Cruickshank (2010). Table 4. Mean fork length of O. nerka less than 100 mm ( ). Year Mean fork length (mm) SE n LGL Limited / Katzie Page 17

25 Steelhead Smolts In 2009 a total of 467 wild (un-marked) steelhead smolts were captured in the Mud Creek trap. Peak catch of wild steelhead occurred on 14 May in 2009, considerably later than the 2008 peak catch on 29 April but similar to the 2007 and 2006 peak catches on 9 May and 12 May respectively. Since enumeration of steelhead began in 2006, the total catch of wild smolts has increased significantly. The 2009 and 2008 catches were almost equivalent (467 and 476 respectively), both of which were more than double the 2007 catch of 227 steelhead and almost double the 2006 catch of 256 steelhead (Figure 8 to Figure 11). Four adipose clipped steelhead were captured in 2009; the three fish measured ranged in size from mm. The adipose clipped steelhead were captured on 24 April, 26 April, 2 May and 30 May. Other Species Many other non-target species were captured in the Mud Creek trap including large numbers of salmonid fry; the majority of these fish were chum. Coho and Chinook fry as well as coho parr and smolts, Chinook parr and smolts, steelhead <90 mm, cutthroat and rainbow trout were also captured in small numbers. In addition to salmonids, dace species, sculpin species, northern pike minnow, red side shiner, peamouth chub, stickleback species, lamprey and crayfish were also captured (Appendix B). Photo 7. Large catch of chum fry in the Mud Creek RST, LGL Limited / Katzie Page 18

26 : n = Daily Wild Steelhead Catch Apr 20-Apr 25-Apr 30-Apr 05-May 10-May 15-May 20-May 25-May 30-May 04-Jun Figure 8. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2006) : n = Daily Wild Steelhead Catch Apr 20-Apr 25-Apr 30-Apr 05-May 10-May 15-May 20-May 25-May 30-May 04-Jun Figure 9. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2007). LGL Limited / Katzie Page 19

27 : n = Daily Wild Steelhead Catch Apr 20-Apr 25-Apr 30-Apr 05-May 10-May 15-May 20-May 25-May 30-May 04-Jun Figure 10. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2008) : n = Daily Wild Steelhead Catch Apr 20-Apr 25-Apr 30-Apr 05-May 10-May 15-May 20-May 25-May 30-May 04-Jun Figure 11. Daily catch of wild (un-marked) steelhead smolts in the Mud Creek RST (2009). LGL Limited / Katzie Page 20

28 DISCUSSION BC Hydro Operations As scheduled, the spillway gate opened 15 April and flows were maintained above 3.0 m 3 /sec until 16 June. A post-surface release flush was scheduled to occur for seven days at the tail end of the migration however once flows reached > 6.0 m 3 /sec safety became a concern and the flush was terminated after only three days. Within this truncated flush period there were no increases in catch documented. As the flush flows were terminated early in 2009 due to safety concerns with the rotary screw trap operations, alternative trapping gear options need to be considered for subsequent years. Mud Creek Trap Operations Although the Mud Creek rotary screw trap was operated consistently during the entire migration period of 2009, the increased flows of the flushing period were too high for safe operation of the trap. One of the primary management questions regarding the O. nerka migration is to determine if the post-surface release flush will encourage more smolts to leave the reservoir, hence other gear options must be explored to allow monitoring to occur safely during the flushing flows in subsequent years. O. nerka The 2009 O. nerka migration estimate was 4,287 (3,833 4,741; 95% CL), the smallest migration estimated since monitoring began in The capture efficiency of 33% was similar to previous years with the exception of 2007; 2007 was unusually low (12%) and resulted in a very large estimate of 62,923 (48,436 77,410; 95% CL) migrants with very broad confidence limits. The low efficiency in 2007 was due to a slide that occurred within Mud Creek, altering the trap site, but as the changes have since been corrected naturally annual trap efficiencies have increased to expected levels again. As daily marking occurred consistently throughout the duration of the run in 2009 a valid estimate of the entire migration (with narrow confidence levels) was obtained. Additional years of full season monitoring with reliable estimates are important for improving our understanding of the timing and magnitude of the population that is migrating from the reservoir. During the last three years of full season monitoring the O. nerka migration has begun in mid April and continued until late May or early June. The 2007 and 2009 migrations both tapered off a week later than the 2008 migration. In 2009 the peak occurred in the latter half of May, substantially later than the late April peaks of the previous two years. Given the variation in peak timing and end date, continued monitoring is important to help improve our understanding of typical run timing. As was the case in 2008, (but contrary to 2007 results) the 2009 peak catch did not correspond to peaks in spillway flow. No increases in catch occurred during the few days of flushing flows at the end of the migration however as the duration was cut short it is still unknown if the flushing period will encourage more smolts to leave the reservoir. The biosampling fork length results indicated that within the size class <100 mm, the 2009 migrants were significantly larger than the 2008 smolts, but smaller than the 2007, 2006 and 2005 migrants. As smaller fish have been observed the last couple of years a new length/weight relationship has been established (Figure 7). LGL Limited / Katzie Page 21

29 Steelhead Smolts The total number of wild steelhead smolts captured in 2009 was almost equivalent to the 2008 total and approximately double the 2007 and 2006 totals. The larger steelhead migration has continued for the second year in a row and will continue to be monitored in subsequent years. It is possible the four marked fish are residualized smolts from the 2006 monitoring project however they are more likely hatchery releases from the 2007 and 2008 stocking programs in the Alouette reservoir. Adult Sockeye Returns The return of adult sockeye for the third year in a row further supports the expectation of an annual return event. Juvenile passage over the Alouette dam has been provided during the spring period since 2005 and is planned to continue throughout the duration of the current WUP (up for review in 2014). Radio telemetry tracking of adults in the reservoir will help to shed light on the spawning behaviour of the sockeye returns and increase the potential for successful reintroduction of the species to the reservoir. RECOMMENDATIONS The following recommendations are made for subsequent years of monitoring of juvenile migration at Alouette reservoir: As planned, maintain a similar spill volume (3.0 to 4.5 m 3 /s ) and timing (mid-april to mid June) of flow releases in 2010; Conduct a post-surface release flush of 6.0 to 9.0 m 3 /s, lasting seven days following the tail end of the out migration period (to occur every two years); during this flush use an alternative gear type (e.g. Inclined Plane Traps) that can be operated safely during the high flows; Conduct daily marking throughout the duration of the run (every second fish) to be used for calculating a population estimate; Collect genetic tissue from approximately 100 individuals of O. nerka for stock identification; and Continue to monitor steelhead migration and total catches of other species, including exotics. LGL Limited / Katzie Page 22

30 ACKNOWLEDGMENTS The cooperation of many people was essential in meeting the objectives of this study. Geoff Clayton, Amanda Balcke and Abby Cruickshank of the Alouette River Management Society (ARMS) are gratefully acknowledged for their assistance throughout this program. Thanks to George Moody and Richard Moody from the Katzie First Nation for their assistance with daily operations and data collection at the Mud Creek trap. We thank Scott Cope (Westslope Fisheries Ltd.) for providing information on the 216 th Street trapping operations. Thanks also to Denis Vaillancourt from the Katzie First Nation for his assistance in planning and coordination. Special thanks go to Dave Hunter and Brent Wilson (BC Hydro) for providing assistance and operations data throughout the study. Thanks to Mark Tiley for his help with RST operation and data collection, CEJ Mussell for his assistance with the start up of the project and Kerry Stratton (LGL) for her assistance with final editing. The support from BC Hydro to alter the operational procedures at Alouette for this study is greatly appreciated. Funding for this project was provided by BC Hydro as part of the Alouette WUP. LGL Limited / Katzie Page 23

31 LITERATURE CITED Baxter, B.E. and R.C. Bocking Field trials to assess coho smolt migration success through the Alouette Reservoir, Report prepared by LGL Limited for BC Hydro Bridge Coastal Fish and Wildlife Restoration Program. BCRP Report No. 05.Al.02 Bengeyfield, W., D. Hay, S. Joyce, and J. Greenbank Evaluation of restoring historic fish passage for anadromous fish at BC Hydro facilities. Report for Power Supply Environment, BC Hydro, Burnaby, BC. Bocking, R.C. and M. N. Gaboury Framework for the evaluation of restoring historic passage for anadromous fish at BC Hydro Bridge-Coastal Generation Area dams. Prepared for Bridge-Coastal Fish and Wildlife Restoration Program. Cope, R.S Alouette River salmonid smolt migration enumeration: 2009 data report. Prepared for Alouette River Management Committee and B.C. Hydro Generation, Burnaby, B.C. Report prepared by Westslope Fisheries Ltd. 55 p. + 1 app. (In draft). Cruickshank, A Alouette adult sockeye enumeration, Report prepared for BC Hydro and Power Authority. Report prepared by ARMS, Maple Ridge, B.C. (In draft) Gaboury, M. N. and R. C. Bocking Feasibility of reintroducing sockeye and other species of pacific salmon in the Alouette Reservoir, BC. Report prepared for Alouette River Management Society, Maple Ridge, B.C. Humble, S.R., A.C. Blakley and R.C. Bocking Field trials to assess steelhead smolt migration success through the Alouette Reservoir, Report prepared for Bridge Coastal Restoration Program. Report prepared by LGL Limited, Sidney, B.C. Mathews, M.A. and R.C. Bocking Evaluation of the migration success of O. nerka (kokanee / sockeye) from the Alouette Reservoir, Report prepared for BC Hydro Bridge Coastal Restoration Program. Report prepared by LGL Limited, Sidney, B.C. Mathews, M.A. and R.C. Bocking Evaluation of the migration success of O. nerka (kokanee / sockeye) from the Alouette Reservoir, Report prepared for BC Hydro Water License Requirements. Report prepared by LGL Limited, Sidney, B.C. Plate, E.M. and R.C. Bocking Alouette Lake sockeye tracking study Report prepared for BC Hydro Bridge Coastal Restoration Program. Report prepared by LGL Limited, Sidney, B.C. Water Survey of Canada Web Site Wilson, G., K. Ashley, M McCusker, R. Land, J. Stockner, G. Scholten, D. Dolecki, D. Sebastian The Alouette Reservoir Fertilization Project: Years 2000 and 2001 experiment, whole reservoir fertilization. Fisheries Project Report No. RD Ministry of Water, Land and Air Protection, Aquatic Ecosystem Section, Province of BC. LGL Limited / Katzie Page 24

32 Appendix A. Physical data at the Mud Creek rotary screw trap site, Date Water Temp (ºC) Precipitation activity (y/n) RST RPM Water Depth (cm) 16-Apr 7 n Apr 7 y Apr 8 n Apr 8 n Apr 8 n Apr 10 n Apr 6 n Apr 8 n Apr 7 n Apr 7 n Apr 7 n Apr 7 n Apr 8 n Apr 10 n Apr 9 n May 9 n May 10 n May 10 n May 9 n May 10 y May 8 n May 9 y May 9 n May 9 n May 9 n May 10 y May 9 n May 9 n May 10 n May 11 n May 12 n May 13 n May 12 n May 9 y May 10 y May 10 n May 10 n May 10 n May 10 n May 11 n May 11 y May 12 n May 12 n May 16 n May 13 n May 13 n Jun 14 n LGL Limited / Katzie Page 25

33 Appendix B. Catch of non-target species at Mud Creek RST, Alouette River, Count & Release Coho / Chinook Date Coho Parr Northern Red Salmonid Chum Chinook Parr Steelhead Dace Sculpin Fry Fry a /Smolt Pike Side Crayfish Peamouth Stickleback Cutthroat Lamprey Rainbow Fry /Smolt <90 mm Spp. Spp. Chub no Clip (<70 mm) a (>70 mm) Minnow Shiner (>70 mm) Other 16-Apr % 1% Apr % 1% Apr % 1% Apr % 1% Apr % 1% Apr >99% < 1% Apr <99% > 1% Apr <99% > 1% 1 < Apr % 1% Apr % 2% Apr >98% < 2% Apr >98% < 2% Apr <98% > 2% Apr % 3% Apr % 2% May % 2% May % 2% May % 2% May % 2% May >98% <2% May >98% <2% May % 3% May 9000 >98% <2% May >98% <2% May >99% <1% LGL Limited / Katzie Page 26