MOSQUITO (ARROW PARK CREEK) CREEK ADFLUVIAL RAINBOW TROUT ASSESSMENT 2012

Transcription

1 MOSQUITO (ARROW PARK CREEK) CREEK ADFLUVIAL RAINBOW TROUT ASSESSMENT 2012

2 MOSQUITO (ARROW PARK CREEK) CREEK ADFLUVIAL RAINBOW TROUT ASSESSMENT 2012 Prepared by Greg Andrusak, RPBio Redfish Consulting Ltd. Nelson, BC September 2012 Prepared for Fish and Wildlife Compensation Program Columbia Basin

3 Cover Photo: Photo of Mosquito Creek at bridge approximately 5 km from Arrow Lakes Reservoir along Fosthall Forest Service Road during adult rainbow trout surveys. Photograph taken on the 6 th of May 2012 by Greg Andrusak. The Fish and Wildlife Compensation Program is a joint initiative between BC Hydro, the BC Ministry of Ministry of Forests, Lands and Natural Resource Operations (MFLNRO) and Fisheries & Oceans Canada (DFO) to conserve and enhance fish and wildlife populations affected by the construction of BC Hydro dams in Canada's portion of the Columbia Basin. Suggested Citation: Andrusak, G.F Mosquito Creek Adfluvial Rainbow Trout Assessment Prepared for the Fish and Wildlife Compensation Program Columbia Basin Nelson, BC. September pp+ i

4 EXECUTIVE SUMMARY Obtaining a better understanding of the distribution and abundance of adfluvial form of large rainbow trout that inhabit the ALR has been considered a management priority following significant ecological impacts due to hydro-electric development within the upper Columbia Basin. The current study was implemented to obtain better information and address data gaps emanating from the regional plan in 2005 for rainbow trout on Arrow Lakes Reservoir (ALR). Importantly, the focus of the study was to confirm the presence or absence of large sized rainbow trout spawners in Mosquito Creek (ALR). A total of four spawner surveys were conducted on Mosquito Creek on April 5, 18, 30, and May 6th. Surveys commenced at the waterfall barrier approximately 21.3 km upstream of the ALR. The barrier itself is formed by large bedrock outcroppings which constricts the creek through a series of bedrock chutes and falls that are approximately m in height and is considered impassable to fish migration. Surveys utilized a helicopter for insertion and covered approximately 17 km from the barrier to the bridge, 5 km above the ALR. Surveys employed downstream snorkel surveys to assess and enumerate spawning individuals. The limited spawner surveys conducted in the spring of 2012 revealed the presence of large adfluvial rainbow trout in Mosquito Creek. A total of six large rainbow trout > 50 cm were observed over the four survey periods. Two of the six fish observed on April 18 were estimated to be between cm. The remaining four fish were observed on May 6 and were estimated to be between cm. The largest rainbow trout, estimated to be near 7 kg in weight, was observed at 19 km along Mosquito Creek. In addition, a total of four large redds, approximately 1 X 1.5 m, were observed during the surveys on May 6 Despite the observed presence of these rainbow trout, there is considerable uncertainty of the size of the escapement, and the run may be relatively small (<100). Nonetheless, it is believed that the run timing is more similar to that of the Gerrard rainbow trout in the Lardeau River based on characteristics of this lake headed system. These findings provide new information that could well have important implications in on-going efforts to improve the recreational fishery on ALR. Further assessment into the size of the escapement and timing of this spawning population is warranted. ii

5 ACKNOWLEDGEMENTS Funding for this project was provided by the Fish and Wildlife Compensation Program Columbia Basin (FWCP). The FWCP is a partnership of BC Hydro, the BC Ministry of Forests, Lands and Natural Resource Operations (MFLNRO), BC Ministry of Environment, and Canada Department of Fisheries and Oceans. Kevin Megale (BC Hydro) and Trevor Oussoren (BC Hydro) are acknowledged and thanked for their assistance with the delivery of this project. Stefan Himmer (biologist), Gary Pavan (biologist), Jimmy Robbins (biologist), are acknowledged for their hard work during the spawner surveys. Special thanks to Highland Helicopters and pilot Mark Homis who provided helicopter service for the survey work. As well, Gary Pavan for organizing all GIS data and providing GIS maps. iii

6 TABLE OF CONTENTS EXECUTIVE SUMMARY...ii ACKNOWLEDGEMENTS... iii TABLE OF CONTENTS... iv LIST OF FIGURES... v LIST OF TABLES... v LIST OF PHOTOS... v INTRODUCTION... 1 Objectives;... 2 BACKGROUND... 2 Rainbow Trout Life History... 2 STUDY AREA... 3 METHODS... 5 RESULTS... 5 Temperature and visibility data... 5 Spawner surveys... 7 DISCUSSION RECOMMENDATIONS REFERENCES iv

7 LIST OF FIGURES Figure 1. Map of Mosquito Creek, a tributary to arrow lakes Reservoir and drainage... 4 Figure 2. Temperature data from spawner surveys conducted on April 5, 18, 30 and May Figure 3. Underwater horizontal visibility data from spawner surveys conducted on April 5, 18, 30 and May Figure 4. Mosquito Creek spawner surveys and observations on April 4, 18 and May 6 based on snorkel surveys. Note-survey on May 6 covered upper 7 km only.. 9 LIST OF TABLES Table 1. Hatchery stocking of Gerrard rainbow trout in Mosquito Creek, an ALR tributary, in 1993 and 1994 (MOE on file) LIST OF PHOTOS Photo 1. Photo of barrier on Mosquito Creek located at 21.3 km on April Photo 2. Photo of barrier on Mosquito Creek located at 21.3 km on April 18, below plunge pool Photo 3. Large LWD accumulations in Mosquito Creek Photo 4. Spawning area identified on spawner surveys on Mosquito Creek Photo 5. Pool habitat within the Mosquito Creek with large LWD accumulations Photo 6. Riffle section of habitat on Mosquito Creek above bridge on main FSR v

8 INTRODUCTION Nearly two decades of studies and assessments have been conducted into understanding the distribution and abundance of piscivorous rainbow trout (Oncorhynchus mykiss) in Arrow Lakes Reservoir (ALR) following significant ecological impacts due to hydro-electric development. Impacts including habitat fragmentation, migration barriers and reduced productivity of the remaining habitat have all been cited and implicated as major issues affecting rainbow trout within the ALR (Sebastian et al. 2000; Moody et al. 2007; Utzig and Schmidt 2011). Despite these impacts the adfluvial form of rainbow trout is still an important part of the sport catch in the recreational fishery on ALR which provides significant economic benefits to the local economy (Arndt and Schwarz 2011). While mitigation and compensation efforts following the footprint impacts relied substantively on hatchery supplementation to maintain the recreational fishery, the modern post-era state of rainbow trout in the ALR appears substantially less productive than the pre-dam era within ALR (Sebastian et al. 2000; Spence et al. 2005). Moreover, little information exits on naturalized or residual population of large adfluvial rainbow (> 50 cm) trout believed to be of the piscivorous ecotype (Andrusak and Slaney 2004, Spence et al. 2005). Pelagic piscivorous rainbow trout are a relatively rare ecotype in the province (DeGisi 2002). In Kootenay Lake, the Gerrard rainbow trout are considered a unique ecotype (Keeley 2007), often attaining large size that can exceed >7 kg. The trophy size trout are highly sought after in the recreational fishery which can generate over 200,000 rod hours. Similarly, an indigenous stock of piscivorous rainbow trout, phenotypically similar to Gerrards, was believed to persist in the Arrow system. However, with the exception of the large rainbow trout (>70 cm) retained in the recreational fishery (Arndt and Schwarz 2011), little is known of their distribution, abundance or spawning locations within the ALR. As a result, local agencies and biologists cooperatively developed a plan for Arrow Lakes Reservoir rainbow trout. The plan created in 2005, describes and outlines a sequence of tasks or priorities to be undertaken over the next 10 years to improve the understanding of various rainbow trout populations that reside in the reservoir (Spence et al. 2005). The main objective of the plan was to identify key tributaries to the ALR which support large piscivorous forms of rainbow trout. This report summarizes a preliminary spawning survey conducted within Mosquito Creek to determine the presence of large adfluvial rainbow trout. Mosquito Creek was selected for this study because it was felt that it had the potential to support large rainbow trout due to its size, stability (lake headed) and warmer water characteristics (Hartman 1969; DeGisi 2002) similar to the characteristics to the Gerrard spawning grounds (Irvine 1978). The primary objective of this study was to confirm the presence of large-sized spawning adfluvial rainbow trout in Mosquito Creek. Identification of a spawning population in this system would provide the FWCP with an 1

9 opportunity to evaluate their contribution to the fishery through a number of future assessments. Objectives; Confirmation of presence or absence of large sized rainbow trout spawners in Mosquito Creek. Counts of spawners observed. Summary report of results including recommendations of future work. BACKGROUND Rainbow Trout Life History Arrow Lakes Reservoir fish populations were poorly understood before development of mainstem Columbia River dams in Canada began in the late 1960s. Peterson and Withler (1965) provided some very general descriptions of fish values prior to completion of the Keenleyside Dam in 1969 but little study occurred thereafter until the late 1970s. There was virtually no environmental assessment of the impacts of Keenleyside or Mica dams on the Upper Columbia system thus background information is very limited. Impact assessment work on Arrow Lakes rainbow trout was not conducted until the proposed construction of the Revelstoke Dam (Martin 1976) and at that time several researchers (Lindsay 1977a, b, 1979; Steigenburger and Elson 1976) concluded that rainbow trout lost due to dam construction could only be replaced by hatchery production. The surveys in the late 1970s and early 1980s related to the impacts of the Revelstoke Dam on the Arrow Reservoir provided some insights into the magnitude of impacts of all the dams. Based on these limited historic assessments and others (Toth and Tsumura 1996; Triton Environmental Consultants Ltd and 1994), three rainbow trout life histories are believed to have been supported within the Arrow basin prior to completion of the dams: stream resident, fluvial and adfluvial (Sebastian et al. 2000; Andrusak and Slaney 2004; Spence et al. 2005). This study was focused on the adfluvial form of rainbow trout that inhabit the Arrow Lakes Reservoir. At least three adfluvial rainbow trout life history types may have existed in the Arrow Lakes prior to the completion of mainstem Columbia River dams including; 1) Smaller sized adfluvial rainbow trout, identified by Lindsay and Seaton (1978) and Lindsay (1979), were typically kg in size and apparently not piscivorous, based on scale analysis. These are typified by the Hill Creek stock, which have been investigated in some detail (Ptolemy 1979). Lindsay (1979) reported estimated rainbow trout run sizes of 100 in Hill Creek, 15 in McKenzie Creek and in the Halfway River. Mosquito Creek is known to support a run of spawning rainbows while Nakusp and Deer creeks are known to 2

10 support small migrant spawners, presumed non-piscivores (H. Andrusak, pers. obs.). The lower reaches of Whatshan and Inonoaklin rivers probably supported spawning rainbow trout prior to flooding by Keenleyside Dam. Lindsay and Seaton (1978) also reported trapping of a number of out-migrating rainbow trout juveniles from Mosquito, Snow, Burton, Caribou, Taite and Eagle creeks. 2) Rainbow trout unique to the ALR system, known locally as yellow-fins, were also once fairly abundant throughout the Arrow Lakes, and were distinguished by their yellow paired fins, opercula and belly (Andrusak and Slaney 2004; Spence et al. 2005). Some of these fish attained sizes up to 9 kg, indicating a piscivorous diet. Others were in the kg range and were probably a littoral, insectivorous form of trout (Andrusak and Slaney 2004; Spence et al. 2005). 3) Finally, Martin (1976) and Lindsay (1979) reported a possible third adfluvial form with some large trout captured below the Mica Dam that were neither yellow-fins nor river residents (Andrusak and Slaney 2004; Spence et al. 2005). STUDY AREA The Mosquito (Arrow Park) Creek watershed (423 km 2 ) originates in the Monashee Mountain range at Mosquito Lake and flows southeast into the Upper Arrow Lake Reservoir (Figure 1). This watershed is in the Arrow Forest District and is accessible via the Arrow Park Ferry, located south of Nakusp, BC, on Highway 6. Elevations range from 444 m along the valley floor to 2300m in the headwaters of Rioulx, Cusson and Plant Creeks. The mainstem flows through a flat, wide valley that extends into the first reaches of all tributaries. Eventually, all tributaries reach steep terrain and several of the upper most reaches of the smaller tributaries are inaccessible to fish. A large waterfall (10 m) located at 21.3 km upstream of the ALR is considered a barrier to migratory fish passage. Arrow Lakes Reservoir extends in a north-south aspect between the Monashee and Selkirk mountain ranges in south central British Columbia (Figure 1). At full pool, the reservoir is 230 km long, has a maximum surface area of 49,500 ha and is comprised of three distinct basins, Lower Arrow, Upper Arrow main basin, and Upper Arrow Beaton Arm. The two main basins are separated by a 30 km section of riverine habitat ( km north of the dam) which ranges in maximum depth from 5-25 meters depending on the water level. The northern-most 45 km of the reservoir is also shallow and riverine, and de-waters annually during the winter and early spring. BC Hydro regulates the reservoir level over a 20 m range to a maximum elevation of m with the lowest levels in March-April and highest in July-August. At maximum drawdown, the length and surface area are reduced to 185 km and 30,700 ha (Sebastian et al. 2000). More detail on the physical and chemical features of the Arrow Reservoir can be found in Pieters et al. (1999). 3

11 Figure 1. Map of Mosquito Creek, a tributary to Arrow Lakes Reservoir and drainage 4

12 METHODS Spring spawner surveys were conducted using daytime snorkel methods on Mosquito Creek to determine the presence or absence of large adfluvial rainbow trout. All surveys commenced at the barrier located approximately 21.3 km upstream from the ALR (Figure 1). Surveys concluded some 17.5 km downstream at the main Forest Service road (FSR) bridge. Surveys were not conducted in the 5 km s below the bridge where the reservoir impacts the river during inundation. Each survey consisted of either one or two member crews (2 people per crew) surveying in a downstream direction, maintaining equidistance within the wetted width to maximize the efficiency of observing fish. The early (April 5 and 18) surveys utilized a helicopter (206 L) from Highland Helicopter in Nakusp for deployment at the start location near the barrier. Use of the helicopter allowed access into the system due to the inability to obtain access via road from snow accumulation over the winter. The subsequent surveys on April 30 and May 6 utilized ATVs to access the river using Forest Service roads. Fish observations were recorded by time, geo-referenced by GPS location and recorded into a waterproof Duksbak notebook. GPS 62s were utilized and configured to have active track logs set to record the surveys. In addition to fish observations, locations of important spawning areas were also recorded. Observations of redds were also recorded, but were not considered an objective of the study. Temperature data was recorded using a handheld thermometer to the nearest ±0.5 C before each survey was conducted. Horizontal visibility during each of the surveys was also recorded underwater using a Secchi disc. RESULTS Temperature and visibility data Temperature data was recorded on each of the surveys dates (April 5, 18, 30, May 6) using a handheld thermometer. Over the four survey dates temperature averaged 6 C, ranging from 5.5 C -6.5 C, demonstrating a gradual increase following the onset of spring runoff (Figure 2). Horizontal visibility was recorded during each of the surveys. In general, counting conditions were ideal with visibility 3 m on April 5, 18 and May 6 (Figure 3). However, the April 30 survey encountered high flows from heavy precipitation that reduced visibility < 1 m as a result of turbidity. As well, visibility was slightly reduced below a section of river approximately16.5 km where the river right bank has de-stabilized and continues to erode two large clay banks. 5

13 Figure 2. Temperature data from spawner surveys conducted on April 5, 18, 30 and May 6. Figure 3. Underwater horizontal visibility data from spawner surveys conducted on April 5, 18, 30 and May 6. 6

14 Spawner surveys A total of four spawner surveys were conducted on Mosquito Creek on April 5, 18, 30, and May 6th. Surveys commenced at the water fall barrier approximately21.3 km upstream of the ALR (Figure 4). The barrier itself is formed by large bedrock outcroppings which constrict the creek through a series of bedrock chutes and falls that are approximately m in height (Photo 1 and Photo 2). No surveys were conducted below the bridge at approximately 5.5 km along the FSR to the ALR since most of this area was within the drawdown area of the reservoir (Figure 4). Surveys on April 5 and April 18, utilized the helicopter for insertion, covered from the barrier approximately 17 km) to the bridge using two crews of two members. The April 30 survey could not be completed due to high flows and high turbidity as a result of heavy precipitation during that week and unseasonably high daytime and evening temperatures. A final survey was conducted on May 6 on the upper 7 km section of the creek following some cool evenings which drastically reduced the discharge, allowing for a survey to be conducted safely. Photo 1. Photo of barrier on Mosquito Creek located at 21.3 km on April 18. Photo 2. Photo of barrier on Mosquito Creek located at 21.3 km on April 18, below plunge pool. 7

15 A total of six large rainbow trout > 50 cm were observed over the four survey periods. Two of the six fish observed on April 18 were estimated to be between cm. The remaining four fish were observed on May 6 and were estimated to be between cm. The largest rainbow trout observed was a male observed approximately 19 km was estimated to be near 7 kg in weight. Less frequently, juvenile rainbow trout and mountain whitefish (Prosopium williamsoni) were also observed throughout the creek during surveys. In addition, a total of four large redds were observed during the surveys on May 6 which had covered an average area of 1 X 1.5 m with their location depicted in Figure 4. Qualitative assessments of suitable spawning locations were also recorded during surveys (4). Much of the habitat within the system below the barrier was a highly complex mixture of heterogeneous habitats characterized by differing gradients, cobblegravel substrates and frequent LWD accumulations (Photo 3; Photo 4; Photo 5 and Photo 6). Andrusak and Slaney (2004) described the habitat in more detail. Photo 3. Large LWD accumulations in Mosquito Creek at approximately 17.5 km. Photo 4. Spawning area identified on surveys in Mosquito Creek at approximately 17.5km. Photo 5. Pool habitat within the Mosquito Creek with large LWD accumulations approximately 14.5 km. Photo 6. Riffle section of habitat on Mosquito Creek above bridge on main FSR approximately 5.5 km. 8

16 Figure 4. Mosquito Creek spawner surveys and observations on April 4, 18 and May 6 based on snorkel surveys. Note-survey on May 6 covered upper 7 km only. 9

17 DISCUSSION Within the upper Columbia Basin, many of the indigenous populations of rainbow trout (fluvial and adfluvial forms) populations have been severely affected by impacts of hydro-electric impoundment and operations (Sebastian et al 2000; Andrusak and Slaney 2004; Spence et al. 2005). Obtaining a better understanding of the distribution and abundance of adfluvial form of large rainbow trout that inhabit the ALR has been considered a management priority (Spence et al. 2005) following significant ecological impacts due to hydro-electric development within the upper Columbia Basin (Moody et al. 2007; Utzig and Schmidt 2011). Sebastian et al. (2000) provides a detailed summary of the historic perspective of the three main sport species (kokanee, rainbow trout and bull trout) within the ALR, and the subsequent assessments following the effects of hydro-electric development. The current study was implemented to obtain better information and address data gaps outlined in the regional plan for rainbow trout on ALR (Spence et al. 2005). In 2012, the observed presence of large adfluvial rainbow trout in Mosquito Creek is an important finding within the ALR. Until now, previous reports have indicated that rainbow trout likely spawn within Mosquito Creek (Sebastian et al 2000; Andrusak and Slaney 2004; Spence et al. 2005), but there has been no direct observation or confirmation of this life history form or size of spawner that utilize the system. While the 2012 surveys confirmed the presence of large adfluvial rainbow trout spawning within this system, there is considerable uncertainty of the magnitude of the escapement. However, based on experience and a number of factors, it is speculated that the run size is relatively small (<100 individuals; discussed below). Nonetheless, the presence of pelagic piscivorous rainbow trout is an important finding in ALR since they are a relatively rare ecotype in the province (DeGisi 2002; Keeley et al. 2007). Given that Mosquito Creek is a lake headed system, it is quite comparable with the Lardeau River (Hartman and Galbraith 1970) which supports large adfluvial rainbow trout spawning. DeGisi (2002) outlines some river/stream characteristics that are common to other known piscivorous rainbow stocks within BC. In addition, Hartman and Galbraith (1970) summarize the characteristics of Gerrard rainbow trout spawning on Kootenay Lake. These characteristics are not essential for rainbow spawning systems but often include; 1) spawning sites that are often located below lake outlets, and or usually in watersheds with several lakes upstream that provide flow stability and clear water 2) potentially support higher water temperatures compared to snow-melt or glacial systems, 3) provide stable and suitable spawning habitat with a compliment of un-embedded gravels and cobble habitats. Based on these qualitative characteristics, it is evident that Mosquito Creek is a very suitable tributary that supports large adfluvial rainbow trout in the ALR as suggested by Sebastian et al (2000); Andrusak and Slaney 10

18 (2004) and Spence et al. (2005). Despite the fact that surveys were concluded by May 6, it is suspected that the Mosquito Creek rainbow spawn timing is similar to that at the Gerrard spawning grounds primarily due to the early onset of freshet and potentially warmer temperatures compared to most of the snow-melt or glacial tributaries that dominate the ALR. With little pre-dam ALR assessment work and the realization that an unknown number of adfluvial piscivores spawned upstream of Revelstoke (Martin 1996) the management agencies at the time were limited to mitigating for loss of large ALR rainbow trout through hatchery augmentation (Lindsay 1977a, b, 1979; Steigenburger and Elson 1976). As a consequence and in retrospect, any unknown piscivore population that persisted and not extirpated or significantly affected by the dam were subsequently influenced by the onset of hatchery augmentation by the 1970s. Starting in the late 1990s, several efforts were made to assess remnant populations of adfluvial rainbow trout within ALR, with a focus on the genetic diversity and whether an indigenous piscivorous stock still existed within the ALR (Taylor and Tamkee 2005). Their study indicated that significant introgression of Gerrard rainbow trout alleles into Arrow Lakes rainbow trout had occurred by the late 1980s, likely a result of hatchery augmentation since the late 1970s (Taylor and Tamkee 2005). Most interestingly, in an effort to improve the recreational fishery and mitigate impacts to rainbow trout in the ALR, Mosquito Creek itself was stocked with approximately 4,500 marked Gerrard rainbow trout yearlings in 1993 and 1994 (Table 1). It is speculated that the spawners observed in Mosquito Creek in 2012 are likely residualized Gerrards from the hatchery out-plants and that may represent a significant contributor of large trout to the fishery, similar to those observed in Hill Creek (McCubbing and Andrusak 2007). Both Hill Creek and Mosquito Creek have been observed to support large spawning rainbow trout that exceed 70 cm, most likely representing the two primary producers of large rainbow trout in the ALR system. It should also be noted that Toth and Tsumura (1996) also identified spawning of large rainbow trout in Tonkawatla Creek (lake headed) near Revelstoke BC, indicating another possible system that produces large trout. Table 1. Hatchery stocking of Gerrard rainbow trout in Mosquito Creek, an ALR tributary, in 1993 and 1994 (MOE on file) RELEASED GAZETTED NAME SPECIES # RELEASED STRAIN GENOTYPE BROOD YEAR AVG WEIGHT LIFE STAGE 1994 MOSQUITO CREEK RB 4437 GERRARD Diploid Yearling 1993 MOSQUITO CREEK RB 4467 GERRARD Diploid Yearling Although the Mosquito Creek spawner surveys may have ceased prior to the peak of spawning, it is believed that the run size is relatively small (<100 individuals). 11

19 Assessment of Gerrard spawn timing and spawning residence time suggest that fish have an average river residence time of >30 days and a spawning residence time of approximately 16 days (Andrusak and Thorley 2012). Based on this residence time information and the few observations of spawning, it is unlikely that large numbers of spawners (> 100) utilize this system. Observations of a number of redds, albeit small numbers, also indicated that spawning had already started. Invariably, it could be argued that these fish may represent the early portion of the spawning run, however based on the observed timing and the imminence of the freshet, it is believed that spawning was or near the peak. Utilization of a resistivity counter would be beneficial in obtaining an estimate of escapement and their run timing in this system. The ability to conduct future spawner assessment and redd surveys on Mosquito Creek is severely limited to the upper 8-9 km of the system near the barrier. Two large clay banks located at 16.5 km and 15 km upstream from ALR are actively transporting fine sediment within the lower section of the creek, creating limited visibility under increased flows (Figure 4). These clay banks were originally assessed in 2003 as compensation options for bank stabilization work to improve rainbow trout survival (Andrusak and Slaney 2004). Stabilizing these banks would likely improve the juvenile rearing conditions in the lower half of the Mosquito Creek, increasing the productive capacity of the system. In summary, the limited spawner surveys conducted in the spring of 2012 revealed the presence of large adfluvial rainbow trout in Mosquito Creek. While there is considerable uncertainty of the size of the escapement, all indications suggest the run is relatively small (<100) and run timing is more similar to that of the Gerrard rainbow trout in the Lardeau River based on characteristics of this lake headed system. These findings provide new information that could well have important implications in on-going efforts to improve the recreational fishery on ALR. This is underscored by the recent creel census data that indicates a decline in catch and success (CPUE) for large rainbow trout in ALR since 2002 (Arndt and Schwarz 2011). Moving forward, further assessment into the size of the escapement and timing of this spawning population is warranted. In addition, the possibility of enhancing the existing population through further hatchery out-planting may be desirable. Genetic information detailed in Taylor and Tamkee (2005) indicate the majority of large rainbow trout in ALR are more similar to Gerrard rainbow trout as a result of hatchery augmentation or the past few decades. Therefore, enhancing the existing residualized stock in Mosquito Creek would be highly beneficial to improving the sport fishery on ALR, while increasing the run strength of large adfluvial rainbow trout, similar to that observed in Hill Creek (McCubbing and Andrusak 2007). 12

20 RECOMMENDATIONS Recommendations are based on the review of the Arrow Lakes Reservoir Rainbow Trout Restoration and Management Plan (Spence et al. 2005) and a historical overview by Sebastian et al. (2000) and Andrusak and Slaney (2004). These include; 1. Conduct preliminary juvenile surveys to assess current juvenile rainbow density 2. Obtain annual temperature and discharge information 3. Develop a GIS meso-habitat layer for Mosquito Creek using BC Government LRDW 1:20,000 ( 4. Obtain a qualitative assessment of suitable spawning and rearing habitat using a GIS meso-habitat layer 5. Establish a practical escapement index for rainbow trout on ALR using a counting fence/resistivity counter on Mosquito Creek to assess rainbow trout escapements 6. Obtain residence time (AUC), run time and spawner movement by selectively radio tagging rainbow trout captured staging off the creek mouth. Information would assist resistivity counter data. 7. Enhance existing stock with diploid Gerrard yearlings to increase the escapement to Mosquito Creek and improve recreational fishing on ALR. 13

21 REFERENCES Andrusak, H. and P. Slaney Status of Kokanee in the Arrow Lakes Reservoir and Initial Assessment of Two Arrow Lakes Reservoir Tributary Streams with Restoration Potential for Spawning Kokanee and Rainbow Trout. Redfish Consulting Ltd., contract report for the Kootenai Tribe of Idaho. Andrusak G.F. and Thorley J.L. (2012) Kootenay Lake Exploitation Study: Fishing and Natural Mortality of Large Rainbow Trout and Bull Trout. A Poisson Consulting Ltd. and Redfish Consulting Ltd. Report prepared for the Habitat Conservation Trust Foundation and Ministry of Forests, Lands and Natural Resource Operations (MFLNRO). HCTF Report No. CAT pp. + app Arndt, S., and C. Schwarz Changes in angling and piscivore condition following 11 years of nutrient additions in Arrow Lakes Reservoir (Arrow Lakes Reservoir creel survey ). Fish and Wildlife Compensation Program Columbia Basin, Nelson, BC. De Gisi, J.S MS. Eutsuk Lake Rainbow Trout: Biology, Population Significance and Fishery Management. Draft Report prepared for BC Parks Skeena District, December 2002, 76 p. Hartman, G.F Reproductive Biology of the Gerrard Stock Rainbow Trout. In: T.G. Northcote (ed.) Symposium on Salmon and trout in streams, H.R. MacMillan Lectures in Fisheries, Univ. of British Columbia: Hartman, G.F. and D.M. Galbraith The Reproductive Environment of the Gerrard Stock Rainbow Trout. BC Fish and Wildlife Branch, Mngt. Publ. 15, 51p. Irvine, J. R. (1978). The Gerrard rainbow trout of Kootenay Lake, British Columbia - a discussion of their life history with management, research and enhancement recommendations. Fisheries Management Report No. 72. Keeley, E. R., E. A. Parkinson and E. B. Taylor (2007). The origins of ecotypic variation of rainbow trout: a test of environmental vs. genetically based differences in morphology. Journal of Evolutionary Biology 20: Lindsay, R. A. 1977a, MS. Revelstoke Dam Fish Compensation on the Upper Arrow Lake, Report to BC Hydro and Ministry of Environment, Fisheries Branch, Nelson, BC. 14

22 Lindsay, R. A. 1977b, MS. Investigations on Fish Populations that will be affected by the Revelstoke 1880 Dam. Report to BC Hydro and Ministry of Environment, Fisheries Branch Ministry of Environment, Nelson, BC. Lindsay, R.A. 1979, MS. Revelstoke Fisheries Dam Assessment, Upper Arrow Lake Annual Report, Ministry of Environment, Nelson, BC. Lindsay, R.A. and D.J. Seaton. 1978, MS. Sport Fishery Compensation Study on Selected Tributary Streams to the Lower Arrow Lake. Fish and Wildlife Branch Nelson, BC. Martin, A.D Investigations on Fish Populations that will be affected by the Revelstoke Dam. BC Fish and Wildlife Branch, Nelson, BC. McCubbing, D.J.F and G.F. Andrusak Fish counter enumeration of Trout spawners at Hill Creek Spawning Channel. Report prepared by Instream Fisheries Research Ltd. In association with Redfish Consulting Ltd. for Fish and Wildlife Compensation Program, Nelson, BC Moody, A., P. Slaney, and J. Stockner Footprint impact of BC Hydro dams on aquatic and wetland productivity in the Columbia Basin. Report prepared by AIM Ecological Consultants Ltd. In association with Eco-Logic Ltd. and PSlaney Aquatic Science Ltd. for Fish and Wildlife Compensation Program, Nelson, BC Peterson, G.R. and I.L. Withler Effects on Fish and Game Species of Development of Arrow Lakes Dam for Hydroelectric Purposes. Management Publication No. 9, British Columbia Fish and Wildlife Branch. Pieters, R. L. C. Thompson, L. Vidmanic, M. Roushorne, J. Stockner, K. Hall, M. Young, S. Pond, M. Derham, K. Ashley, B. Lindsay, G. Lawrence, D. Sebastian, G. Scholten, F. McLaughlin, A. Wuest, A. Matzinger and E. Carmack Arrow Reservoir limnology and trophic status report, year 2 (1998/99). RD 72, Fisheries Branch, Ministry of Environment, Lands and Parks, Province of British Columbia. Ptolemy, R.A MS. Production and Stream Carrying capacity Relative to the Design of a Rearing Channel for Rainbow Trout on Hill Creek near Galena Bay, West Kootenay. Fish and Wildlife Branch, Ministry of Environment, Victoria BC. 48p. Sebastian, D., H. Andrusak, G. Scholten and L. Brescia Arrow Reservoir Fish Summary. Stock Management Report Province of British Columbia, Ministry of Fisheries. 15

23 Spence, C.R., H. Andrusak, J.A. Burrows and J.S. Baxter Arrow Lakes Reservoir Rainbow Trout Restoration and Management Plan Ministry of Environment Rep. Steigenburger and Elson Stream Surveys and Fisheries Compensation Studies of Tributaries to the Upper Arrow Lakes Reservoir Revelstoke 1880 project) Northern Natural resource Services Ltd. Report prepared for BC hydro Authority, Vancouver BC. 239 p. Taylor, E.B. and P. Tamkee Microsatellite DNA Polymorphism in Rainbow Trout (Oncorhynchus mykiss) from the Upper Arrow and Kinbasket Watersheds in British Columbia, Part III: Analysis of historical samples to assess introgression between introduced Kootenay Lake trout and native Arrow Lakes trout. Report prepared for the Columbia Basin Fish and Wildlife Compensation Program, Nelson, BC. Report prepared by Department of Zoology, Biodiversity Research Centre, and Native Fishes Research Group, University of British Columbia. pp 27. Toth, B.M. and K. Tsumura Arrow Lakes Rainbow Trout Broodstock Collection. Columbia Fish and Wildlife Compensation Program Project. Ministry of Environment, Lands and Parks Fisheries Branch Fisheries Technical Circular No. RD Triton Environmental Consultants Ltd Biophysical Surveys and Enhancement Opportunities for Tributaries of the Upper Columbia River. Contract report to: Mica Fisheries Technical Committee of BC Hydro and the BC Ministry of Environment, Lands and Parks. Triton Environmental Consultants Ltd Tonkawatla Creek Rainbow Trout Evaluation and Broodstock Collection. Consultant report prep. by Triton Environmental Consultants Ltd. for Columbia Basin Fish and Wildlife Compensation Program, Nelson, BC. Utzig, G. and D. Schmidt Dam Footprint Impact Summary-BC Hydro Dams in the Columbia Basin. Contract report prepared for the Fish and Wildlife Compensation Program-Columbia Basin, Nelson BC. 16