Status and Habitat Use of Snake River White Sturgeon Associated with the Hells Canyon Complex

Ken Lepla Project Biologist

Technical Report Appendix E.3.1-6 Revised July 2003 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company

Status of Snake River White Sturgeon Associated with the Hells Canyon Complex

Ken Lepla Project Biologist

James A. Chandler Fish Biologist

Phil Bates Fisheries Technician

Technical Report Appendix E.3.1-6 Status and Habitat Use of Snake River White Sturgeon Associated with the Hells Canyon Complex

Chapter 1 November 2001 Revised July 2003 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company

Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

TABLE OF CONTENTS

Table of Contents...... i

List of Tables ...... iii

List of Figures...... iii

List of Appendices ...... v

Abstract...... 1

1. Introduction...... 2

2. Study Area ...... 2

3. Methods...... 4

3.1. Collection Methods...... 4

3.2. Analysis Methods...... 5

4. Results...... 7

4.1. Swan Falls–Brownlee Reach ...... 7

4.1.1. Population Abundance and Structure...... 7

4.1.2. Telemetry ...... 8

4.2. Brownlee Dam–Hells Canyon Dam Reach...... 8

4.2.1. Population Abundance and Structure...... 8

4.2.2. Telemetry ...... 9

4.3. Hells Canyon–Lower Granite Reach ...... 9

4.3.1. Population Abundance and Structure...... 9

4.3.2. Telemetry ...... 10

5. Discussion...... 11

5.1. Swan Falls–Brownlee Reach ...... 11

5.2. Brownlee–Oxbow–Hells Canyon Reaches...... 13

Hells Canyon Complex Page i Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

5.3. Hells Canyon–Lower Granite Reach ...... 14

5.4. Telemetry ...... 16

6. Summary and Conclusions ...... 18

6.1. Swan Falls–Brownlee Reach ...... 18

6.2. Brownlee–Hells Canyon Reach ...... 18

6.3. Hells Canyon–Lower Granite Reach ...... 19

6.4. Telemetry ...... 19

7. Acknowledgments...... 20

8. Literature Cited ...... 20

Page ii Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

LIST OF TABLES

Table 1. Summary of effort and catch (including recaptures) for white sturgeon sampled in Snake River reaches from Swan Falls Dam to the mouth of the Salmon River...... 25

Table 2. Abundance estimates for white sturgeon populations in Snake River reaches between Swan Falls Dam and Lower Granite Dam...... 26

Table 3. Mean length of white sturgeon 3 to 45 years old sampled in the Snake River from Swan Falls Dam to the mouth of the Salmon River...... 27

Table 4. Stage of maturity of white sturgeon sampled in the Snake River from Swan Falls Dam (RM 458) to the mouth of the Salmon River (RM 188)...... 28

Table 5. Summary of movement by telemetered white sturgeon in the Swan Falls−Brownlee reach of the Snake River...... 29

Table 6. Summary of movement by telemetered white sturgeon in the Oxbow−Hells Canyon reach of the Snake River...... 30

Table 7. Mortality and survival estimates for white sturgeon sampled in the Snake River between Bliss and Lower Granite dams...... 30

Table 8. Summary of movement by telemetered white sturgeon in the Hells Canyon−Salmon River reach of the Snake River...... 31

Table 9. Mean relative weights based on fork length measurements for white sturgeon populations in the Snake River between Bliss and Lower Granite dams...... 32

LIST OF FIGURES

Figure 1. Map of Snake River reaches between Swan Falls Dam and the Salmon River that Idaho Power Company sampled for white sturgeon...... 33

Figure 2. Gear selectivity rates for white sturgeon sampled with setline and gill net gears in the Snake River...... 35

Figure 3. Distribution of Snake River white sturgeon between Swan Falls and Lower Granite dams. Data below Hells Canyon Dam include sturgeon

Hells Canyon Complex Page iii Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

sampled by the Nez Perce Tribe between the Salmon River and Lower Granite Dam...... 36

Figure 4. Setline catch rates and hours of effort expended during sampling of white sturgeon in the Snake River from Swan Falls Dam to the mouth of the Salmon River...... 37

Figure 5. Gill net catch rates and hours of effort expended during sampling of white sturgeon in the Snake River downstream of Swan Falls Dam to the mouth of the Salmon River...... 38

Figure 6. Length-frequency distributions (adjusted for gear selectivity) of white sturgeon sampled with setlines in the Snake River reaches from Swan Falls to Lower Granite dams...... 39

Figure 7. Length-frequency distribution (adjusted for gear selectivity) of white sturgeon sampled by gill nets in the Snake River between Swan Falls and Brownlee dams...... 40

Figure 8. Mean length-at-age and von Bertalanffy growth (VBG) lines for white sturgeon in the Snake River between Swan Falls and Lower Granite dams in graphs a) and b). VBG function for Hells Canyon−Lower Granite sturgeon population was estimated by Tuell and Everett (2001) using combined age data from IPC and Nez Perce Tribe 1997–2000 sturgeon surveys...... 41

Figure 9. Length-weight relationships for white sturgeon sampled in the Snake River downstream of Swan Falls and Hells Canyon dams...... 42

Figure 10. Relative weights of white sturgeon sampled in the Snake River between Swan Falls and Lower Granite dams. Length and weight data below Hells Canyon Dam were combined with sturgeon data collected by the Nez Perce Tribe...... 43

Figure 11. Range of movement activity for telemetered white sturgeon in Snake River reaches between Swan Falls Dam and the mouth of the Salmon River...... 44

Figure 12. Locations of telemetered white sturgeon (S555, S285, S357, S3434) in Brownlee Reservoir...... 45

Figure 13. Seasonal range of activity (between tracking events) for telemetered white sturgeon in Snake River reaches between Swan Falls Dam and the mouth of the Salmon River. Small boxes indicate median values, large boxes the 25th and 75th percentiles, and vertical lines the minimum and maximum values...... 46

Page iv Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Figure 14. Length-frequency distribution of white sturgeon collected by setline hook sizes (10/0, 12/0, 14/0, 16/0) in the Snake River between Swan Falls Dam and the mouth of the Salmon River below Hells Canyon Dam...... 47

Figure 15. Length frequencies of white sturgeon sampled by angling gear in the Snake River below Hells Canyon Dam during Idaho Power Company and Nez Perce Tribe sturgeon surveys...... 48

Figure 16. Mean daily water temperatures in the Snake River at Swan Falls Dam (1991–2000) and Weiser, Idaho (1996–2000)...... 49

Figure 17. Size composition of white sturgeon sampled between Swan Falls and Brownlee dams. Idaho Department of Fish and Game data for 1986–87 were obtained from IDFG's White Sturgeon Management Plans (1992 draft)...... 50

Figure 18. Size composition of white sturgeon sampled in the Snake River between Hells Canyon and Lower Granite dams...... 51

Figure 19. Distance traveled between capture periods by white sturgeon in the Snake River between Bliss and C.J. Strike dams...... 52

LIST OF APPENDICES

Appendix 1. Locations of telemetered white sturgeon (R120, S248, S456) in the Snake River between Swan Falls and Brownlee dams...... 53

Appendix 2. Locations of telemetered white sturgeon (S357, S285) in the Snake River between Swan Falls and Brownlee dams...... 54

Appendix 3. Locations of telemetered white sturgeon (S555, S384) in the Snake River between Swan Falls and Brownlee dams...... 55

Appendix 4. Locations of telemetered white sturgeon (S375, R133) in the Snake River between Swan Falls and Brownlee dams...... 56

Appendix 5. Locations of telemetered white sturgeon (S339, S3434) in the Snake River between Swan Falls and Brownlee dams...... 57

Appendix 6. Locations of telemetered white sturgeon (S2443, S447, S2525) in the Snake River between Oxbow and Hells Canyon dams...... 58

Appendix 7. Locations of telemetered white sturgeon (S375, S622, S2543) in the Snake River between Hells Canyon and Lower Granite dams...... 59

Hells Canyon Complex Page v Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 8. Locations of telemetered white sturgeon (S365, S456, S249) in the Snake River between Hells Canyon and Lower Granite dams...... 60

Appendix 9. Locations of telemetered white sturgeon (S455/S248, S294, S276) in the Snake River between Hells Canyon and Lower Granite dams...... 61

Appendix 10. Locations of telemetered white sturgeon (S34, S2236/S254, S356, S2353) in the Snake River between Hells Canyon and Lower Granite dams...... 62

Appendix 11. Locations of telemetered white sturgeon (S510, S2255, S366, S2336) in the Snake River between Hells Canyon and Lower Granite dams...... 63

Appendix 12. Locations of telemetered white sturgeon (S377, S465, S239, S933) in the Snake River between Hells Canyon and Lower Granite dams...... 64

Page vi Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

ABSTRACT

The Aquatic Resources Work Group, with representatives from state, federal, tribal, and non- governmental entities, identified white sturgeon (Acipenser transmontanus) as one of several aquatic species affected by the Hells Canyon Complex. Because recent information on sturgeon populations associated with the Hells Canyon Complex was limited, investigating the status of current sturgeon populations was warranted. Catch rates and overall numbers of sturgeon captured during sampling between Swan Falls and Brownlee dams were very low. Most fish were captured near the upstream end of the reach, between Swan Falls and Walters Ferry. Sturgeon populations consisting primarily of subadult and adult sturgeon, with few fish measuring less than 92 cm total length (TL), indicate that recruitment levels have remained poor since earlier IDFG surveys. Relative weights, averaged for all sturgeon sampled, were similar to the relative weights of the Hells Canyon population; however, sturgeon in Brownlee Reservoir had a significantly lower condition factor than the sturgeon in other Snake River reservoirs. Severe water quality degradation, particularly in the lower river and in Brownlee Reservoir, appear to be limiting white sturgeon in this reach. The status of sturgeon in Oxbow and Hells Canyon reservoirs appears unchanged over the past 30 years, with few wild white sturgeon remaining in either pool. The capture of only three adult sturgeon in Hells Canyon Reservoir suggested that opportunities for reproduction are infrequent, and the absence of small sturgeon indicated that no recent recruitment has occurred. The sturgeon population between Hells Canyon and Lower Granite dams is the largest population in Snake River reaches above Lower Granite Dam. Juvenile fish less than 92 cm TL continue to dominate the population, and size groups greater than 92 cm TL have steadily increased since the 1970s. Survival estimates were similar to rates observed in several Snake River populations, and the trend of mean relative weights for sturgeon downstream of Hells Canyon Dam showed that the fish condition has not declined since earlier surveys conducted from 1972 to 1975 and from 1982 to 1983. The current sturgeon population below Hells Canyon is genetically diverse and exhibits a healthy population structure, based on the current stock structure dominated by juveniles, wide range of size classes, and stages of maturity from immature juveniles to reproductive adults. A total of 35 white sturgeon—comprised of nine females (ranging in maturity from previtellogenic to spent condition), ten males (ranging in maturity from nonreproductive to reproductive condition) and five fish of unknown sex—were fitted with radio and sonic transmitters between Swan Falls Dam and the Salmon River. These fish ranged in lengths from 139 to 276 cm TL and were at large from 85 to 910 days during our tracking efforts. Total distance traveled by sturgeon during our monitoring efforts ranged from 0.9 to 96.3 miles; however, the overall range of movement activity (farthest distance upstream or downstream) was fairly localized, with 73% of the fish in the Swan Falls-Brownlee and Hells Canyon–Salmon River segments traveling less than 10 mi from their initial capture locations. The farthest distance traveled by sturgeon in the Oxbow– Hells Canyon segment (from their initial capture locations) was 11.1 to 15.9 miles. The average distances traveled by all sturgeon during our monitoring efforts was from 0.4 to 4 miles.

Hells Canyon Complex Page 1 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

1. INTRODUCTION

White sturgeon, Acipenser transmontanus, are considered a species of special concern by the State of Idaho (Mosley and Groves 1990). Many factors—including altered habitat, pollution, historical exploitation, and populations fragmented by dams—have contributed to the current status of sturgeon in the Snake River. The abundance of Snake River sturgeon apparently began declining in Idaho as early as the late 1930s (Edson 1956). At the time, four dams had been built on the Snake River between 1901and 1937 (Swan Falls, Shoshone Falls, Lower Salmon Falls, Upper Salmon Falls), which impounded only about 4% of the river. Overharvest was believed to be the primary factor responsible for their decline, and fishing regulations were soon implemented beginning in 1943. Commercial fishing, which began in the mid-1890s, was prohibited and increasingly restrictive sport regulations followed until 1970, when a catch-and- release fishery program was adopted for the entire Snake River in Idaho. During the period from 1949 to 1975, nine more dams (Bliss, C.J. Strike, Brownlee, Oxbow, Hells Canyon, Ice Harbor, Little Goose, Lower Monumental, and Lower Granite) were also built on the Snake River, which further altered and fragmented riverine habitats.

Idaho Power Company (IPC) operates nine hydroelectric projects on the Snake River downstream of Shoshone Falls, including the three facilities (Brownlee, Oxbow and Hells Canyon dams) in the Hells Canyon reach of the Snake River and collectively known as the Hells Canyon Complex (HCC). In 1996, IPC initiated a study to evaluate the status of white sturgeon in the reaches associated with the HCC as part of their efforts to relicense these projects. Consultation efforts with the Aquatic Resources Work Group (ARWG), which consist of regional representatives from state, federal, tribal, and public entities, identified white sturgeon as one of several aquatic species affected by the HCC. The ARWG expressed concern over impacts to the viability and persistence of sturgeon populations in the Snake River that are isolated by IPC dams.

Fishery investigations of sturgeon populations associated with the HCC showed that abundance varied widely among these reaches (Welsh and Reid 1971, Reid et al. 1973, Coon et al. 1977, Cochnauer et al. 1985, Lukens 1985, Reid and Mabbot 1987). These surveys indicated that large numbers of sturgeon were found only between Hells Canyon and Lower Granite dams with considerably lower numbers between Hells Canyon and Swan Falls dams. Welsh and Reid (1971) reported that the species is probably not abundant in Oxbow Reservoir, and none were sampled in Hells Canyon Reservoir. The lack of recent population information warranted further investigation; therefore, the goal of this report is to describe the current status of white sturgeon in Snake River reaches associated with the HCC.

2. STUDY AREA

The study area for sampling sturgeon consisted of four reaches described below. Reaches sampled by IPC extended 270 miles (mi), from Swan Falls Dam (river miles [RM] 458) downstream to the mouth of the Salmon River (RM 188). Below the Salmon River confluence,

Page 2 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon the Nez Perce Tribe also conducted sampling for sturgeon downstream from RM 188 to Lower Granite Dam (RM 107.5) (Figure 1).

Swan Falls–Brownlee Reach—The Snake River below Swan Falls Dam is free flowing for 118 mi before it enters Brownlee Reservoir, the reservoir farthest upstream in the HCC. Three habitat segments can generally characterize this reach. The upper 8-mi segment of river between Swan Falls Dam and Celebration Point (RM 458–RM 450) is relatively high gradient, with vertical canyon walls, turbulent runs and rapids, and intermittent deep pools. Downstream of Celebration Point, the gradient lowers and the river becomes shallow, with numerous island complexes and braided channels. This stretch extends for 110 mi through agricultural farmlands before entering Brownlee Reservoir near RM 340. Brownlee Reservoir has approximately 1 million acre-feet of active storage and a surface area of 6,100 acre-feet at full pool (2,077 ft mean sea level). Its average depth is 32 m, with a maximum depth of 92 m. During winter, reservoir drawdowns commonly approach 30 m to meet the requirements established by Army Corps of Engineers for flood control. Brownlee Reservoir is used for power, flood control, and recreation. Several large tributaries empty into this reach, including the Boise, Malheur, Payette, Owyhee and Weiser rivers. Nutrient loading from agricultural, municipal, and industrial sources is high in this reach (Myers et al. 1998, Harrison et al. 1999, Hoelscher and Myers 2001). Brownlee Dam is located at RM 284.6.

Brownlee–Oxbow Reach—The second project in the HCC is Oxbow Dam (RM 273), located 12 mi downstream of Brownlee Dam. Oxbow Reservoir extends to the tailrace of Brownlee Dam and has a surface area of 1,150 acres. Maximum depths reach about 30 m, and the water level commonly fluctuates 1.2 m daily. Wildhorse River is the only major tributary entering into this reach. Oxbow Reservoir has been designated as water quality limited. In large part, processes in Brownlee Reservoir cause the conditions that warrant this designation (Myers and Pierce 1999).

Oxbow–Hells Canyon Reach—The third dam in the HCC is Hells Canyon Dam (RM 247.6), which impounds water for about 25 mi. This reservoir has a surface area of 2,412 acres at normal full pool and total storage of 167,720 acre-feet. The reservoir has a maximum depth of 60 m and is characterized by steep shorelines with basalt outcrops and talus slopes. This reach consists primarily of impounded reservoir habitat and little free-flowing habitat with the exception of the tailrace and Oxbow Bypass, a 2.5-mi segment of the Snake River lying between the Oxbow Dam and tailrace to the powerhouse downstream.

Hells Canyon–Lower Granite Reach—The Snake River below Hells Canyon Dam is free flowing for 107 mi before entering Lower Granite Reservoir. This section of river runs through the deepest river-carved canyon in North America, which creates a series of turbulent rapids and runs intermixed with many deep pools. High mountain peaks, basalt canyon rimrocks, and steep sage-covered lower slopes characterize the Hells Canyon corridor. Several large tributaries— including the Imnaha, Salmon, and Grande Ronde rivers—join the Snake River above Lower Granite Reservoir.

Hells Canyon Complex Page 3 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

3. METHODS

Standardized methods were used for capturing and analyzing data on white sturgeon populations throughout the reaches of the study area.

3.1. Collection Methods

Sampling Design—From the upstream end of Brownlee Reservoir to the mouth of the Salmon River, the Snake River was divided into increments of 0.1 river mile, with each increment representing a potential sample transect. We randomly selected sample transects within each project reach and fished with the collection gear set in the deepest cross-section (thalweg) of the channel. To collect these population data, we conducted a total of four to five sample passes in each reach. When sampling nonrandom locations, we supplemented our collection effort by placing additional gear sets in probable sturgeon habitat.

Above Brownlee Reservoir, we conducted preliminary, or synoptic, sampling to initially determine the abundance and distribution of sturgeon to Swan Falls Dam. Twenty-six sturgeon were captured near the upstream end of the reach between RM 450 and Swan Falls Dam. No sturgeon were caught during sampling in the low-gradient section of river between Celebration Point (RM 450) and the upper end of Brownlee Reservoir. For the reach above Brownlee Reservoir, we decided to conduct our full sampling effort only from Swan Falls Dam downstream to Walters Ferry, which is located 6 mi downstream of Celebration Point. This decision was based on information collected during the synoptic survey and our need for timely field collection.

Below the confluence of the Snake and Salmon rivers (in the lower extent of our study area), the Nez Perce Tribe sampled for white sturgeon from the Salmon River to Lower Granite Reservoir (1997–2000) using collection gear and sampling protocols similar to IPC’s. Field data collected below Hells Canyon Dam by IPC and the Nez Perce Tribe were combined according to a data-sharing agreement between the two parties. The combined data were used to estimate abundance, size distribution, length-weight relationships, age and growth, and relative weights of the sturgeon population between Hells Canyon and Lower Granite dams.

Collection Gear—We used baited setlines as the primary gear for sampling for white sturgeon because of the versatility of this gear in effectively sampling a wide range of habitats. Each setline was 27 m long and equipped with 6 circle tuna hooks. Two of each hook size (12/0, 14/0, and 16/0) were attached in random order to the mainline and spaced 3 m apart. A few setlines were also rigged exclusively with 10/0 hooks to capture smaller white sturgeon. We used line weights (10 kg) to anchor the ends of our setlines and attached a float line and buoy for retrieval. Each week of the sampling period, we fished up to 12 setlines over a three-day period and checked the setlines at daily intervals.

To supplement our effort using baited setlines, we used sinking style gill nets extensively above Hells Canyon Dam in the HCC reservoirs and in areas of low water velocity. Each net was constructed of multifilament twine and measured 38.4 m long, with bar mesh sizes ranging from

Page 4 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

1.9 to 12.7 cm. We fished all gill nets for 1-hour intervals or less. Below Hells Canyon, IPC did not use gill nets because of the risk of capturing species listed as threatened or endangered under the Endangered Species Act. When time permitted, limited angling occurred.

Capture and Handling—We placed captured sturgeon into a vinyl stretcher with circulating water that allowed the fish to respire throughout the handling time. Fish that were too large to handle onboard were examined alongside the boat. We recorded pectoral girth and fork and total lengths to the nearest centimeter and weight to the nearest 0.1 kg. We tagged the white sturgeon by inserting 125-kHz Passive Integrated Transponder (PIT) tags into the musculature at the base of the right side of the dorsal fin. At the request of Idaho Department of Fish and Game, we also removed the second left-lateral scute from sturgeon below Hells Canyon Dam to serve as an external mark for distinguishing recaptured sturgeon. Sex and stage of maturity were determined surgically according to methods outlined in Conte et al. (1988) and Beamesderfer et al. (1989) for sturgeon greater than 150 cm TL. We injected a post-surgery antibiotic, oxytetracycline (OTC) (200 mg/ml), into the dorsal muscle at the dose of 5 mg of OTC per kilogram of body weight. To minimize the stress to the sturgeon, we conducted no sampling in areas where the near-substrate dissolved oxygen was less than 70% saturation.

Telemetry—Thirty-five white sturgeon comprising various life stages between Swan Falls Dam and the mouth of the Salmon River were fitted with both radio and ultrasonic transmitters to monitor movement behavior. Transmitters were mounted externally by passing a single braided stainless steel wire through end holes in the tag. A 15.2-cm 16-gauge hypodermic needle was inserted through the flesh just below the anterior and posterior edges of the dorsal fin. Wire was threaded through holes in a piece of PVC tubing with equal dimensions of the transmitter on the other side of the dorsal. The wire was then cut and crimped with stainless steel cable sleeves to secure the transmitter. Tags operated on various frequencies (kHz) and emitted unique codes for individual fish identification. A directional hydrophone and receiver (Sonotronics Model USR-4D™)1 were used to locate sonic transmitters. Three and six-element directional yagi antennas with a Lotek TM SRX_400 radio receiver2 were used to locate radio transmitters.

3.2. Analysis Methods

Population Abundance—We used Program Jolly, an open population model, to estimate the sturgeon population between the mouth of the Salmon River and Hells Canyon Dam. Program Jolly performs the matrix calculation and 95% confidence intervals. Abundance of sturgeon above Hells Canyon Dam was estimated using a modified Schnabel method (closed population estimator) with less than 10% recapture rate:

N = ∑(Ct × Mt) / [(∑rt) + 1]

1 USR-4D is a trademark of Sonotronics, Inc. 2 Lotek and SRX_400 are trademarks of Lotek Wireless.

Hells Canyon Complex Page 5 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

where

Ct = total number of sturgeon taken during pass t,

Mt = total number of marked fish at start of pass t,

rt = number of recaptured sturgeon in the sample Ct

Confidence intervals (95%) were calculated by

r′ = (∑rt) + 1.92 ± 1.96 × [sqrt (∑rt + 1)]

White sturgeon that were recovered in the same sample interval in which they were marked were not counted as recaptures in the population estimate. We determined relative abundance and distribution of white sturgeon in each reach by computing catch rates (fish/hr) by gear type.

Population Structure—We made corrections for setline and gill net selectivity by using mark- recapture data—specifically the ratio of recaptures to marks at large—to estimate sturgeons’ vulnerability to the respective gears. A smooth function was fit to the data and used to correct observed length frequencies by dividing the observed frequency in each size class by the predicted vulnerability (Beamesderfer and Rieman 1988) (Figure 2). We then used the adjusted length-frequency distributions to evaluate the population structure. We used paired lengths (cm) and weights (kg) to calculate length and weight relationships according to a standard allometric β function: W = α × L . Relative weights (Wr) were calculated to assess the relative condition of 3.232 sturgeon based on the standard weight equation, Ws = 2.735E-06 × FL , developed for white sturgeon by Beamesderfer (1993). Differences among relative weights for reaches were calculated using a nonparametric Wilcoxon 2-Sample Test (SAS Institute 1990). The surgical inspection of gonads also allowed us to estimate sex ratio, stage of maturity, and proportion of females spawning each year.

The ages of the white sturgeon were estimated from thin cross-sections of the leading edge of the pectoral fin rays. The fin sections were sent to the University of Idaho (Dennis Scarnecchia, College of Natural Resources, UI) for experienced staff to estimate ages. We then combined the estimated age data of the sturgeon above the Salmon River with age data collected by the Nez Perce Tribe for fish between the Salmon River and Lower Granite Dam. A von Bertalanffy –k(t – to growth (VBG) function Lt = L∞ [1 – e )] (Ricker 1975) was used to describe age-at-length.

We calculated instantaneous total mortality (Z) from a regression of the slope for the descending limb of a log-transformed catch curve (Ricker 1975). Natural log of catch was then fitted with a linear regression on greater than five observations to determine absolute Z. Approximate 95% confidence limits for Z were estimated from the regression as ± 2 standard error (SE). Total annual mortality (A) was then derived by A = 1 – S, where the survival rate S = e–Z.

We collected blood and 1-cm2 pieces of fin tissue from up to 100 sturgeon per reach for DNA analysis. Blood (2 ml) was taken from the ventral surface of the caudal peduncle posterior to the anal fin and stored until samples could be frozen. Fin-tissue samples taken in lieu of blood were placed in sterile vials with 5 ml of lysis buffer and stored at room temperature. These samples were added to an existing database at the Center for Salmonid and Freshwater Species at Risk at

Page 6 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

the University of Idaho for evaluating the genetic variability among white sturgeon populations in the Columbia Basin (Anders et al. 2000).

Telemetry—Movement activity (distance traveled) of individually telemetered fish was monitored weekly from spring through fall months and biweekly during winter months. Seasonal periods were defined as 1) spring: March 20–June 20, 2) summer: June 21–September 22, 3) fall: September 23–December 20, and 4) winter: December 21–March 19.

4. RESULTS

4.1. Swan Falls–Brownlee Reach

4.1.1. Population Abundance and Structure

A total of 16,752 setline hours, 268 gill net hours and 18 angling hours of effort was expended to capture 45 white sturgeon (including 3 recaptures) between Swan Falls and Brownlee dams (Table 1). Most sturgeon (n = 34) were sampled within 8 mi of Swan Falls Dam, while 11 sturgeon were captured near the upper end of Brownlee Reservoir between RM 326.6 and RM 331.6 (Figure 3). In fact, nine of the eleven sturgeon in Brownlee Reservoir were sampled at one location near the mouth of the Burnt River (RM 327.8) from August 13 to August 21, 1997. Overall, catch rates for sturgeon were poor regardless of the fishing gear used. The highest catch rates (0.065 fish/hr) for sturgeon in this reach using setline gear was near Swan Falls Dam (Figure 4), while gill nets captured sturgeon at only three locations in the reach (Figure 5). We estimated the abundance of sturgeon greater than 70 cm TL between Swan Falls Dam and Walters Ferry at 155 individuals (95% CI 70–621), or 11 fish per river mile (Table 2). We were unable to estimate the white sturgeon population for Brownlee Reservoir because of the low number of fish captured during our random sampling.

The sturgeon caught with setlines in this reach ranged from 85 to 290 cm TL, with 4% of the fish measuring less than 92 cm TL, 26% measuring between 92 and 183 cm TL, and 70% measuring greater than 183 cm TL (Figure 6a). Sturgeon captured with gill net gear showed a similar size distribution, with larger fish dominating (Figure 7).

Ages ranging from 9 to 45 years and lengths ranging from 110 to 276 cm TL were assigned to 20 sturgeon sampled between Swan Falls Dam and Walters Ferry and one sturgeon from Brownlee Reservoir (Table 3). Length-at-age was described by the following VBG: Lt = 290 {1 – e [–0.046 × (t +1.117)]} (Figure 8a). Paired fork length and weight measurements were obtained from 35 sturgeon ranging in length from 75 to 259 cm FL and in weight from 3.0 to 132.8 kg. We used the following equation to describe this length-weight relationship: Wt = 2.264E-06 × TL 3.16 (Figure 9a). Mean relative weight of sturgeon in Brownlee Reservoir (82%) was lower than mean relative weight of sturgeon captured near the upper end of the reach (87%). Mean relative weight for all sturgeon sampled between Swan Falls and Brownlee dams was 86% of the standard weight for white sturgeon (Figure 10a).

Hells Canyon Complex Page 7 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Twenty-three sturgeon measuring greater than 150 cm TL were surgically examined to determine sex and stage of maturity. Of these fish, 16 were identified as females and 7 as males. The distribution among stages of maturity for females was 53% previtellogenic, 29% early vitellogenic, 12% ripe, and 6% previtellogenic with attritic oocytes. Among males, 57% were nonreproductive while 43% were reproductive (Table 4). The number of spawning females measuring greater than 150 cm TL in the total population for this reach was estimated at 7 (95% CI 3–29).

4.1.2. Telemetry

Eleven sturgeon—comprising seven females (ranging in maturity from previtellogenic to ripe condition), two males (reproductive condition), and two fish of unknown sex—were fitted with radio and sonic transmitters. These fish ranged in lengths from 143 to 276 cm TL and were at large from 185 to 475 days during our tracking efforts. Sturgeon were tagged in two areas, in the canyon section below Swan Falls Dam and the upper end of Brownlee Reservoir. Total distance traveled by sturgeon during monitoring efforts ranged from 0.9 to 34 mi (Table 5). Overall, the range of movement activity (farthest distance upstream or downstream) was fairly localized with 73% of the fish traveling less than 10 mi from their initial capture. The average distance traveled by sturgeon during our monitoring ranged from 0.4 mi below Swan Falls Dam and 1.3 mi in Brownlee Reservoir (Figure 11a). Sturgeon tagged in Brownlee Reservoir generally remained near the upper end of the pool (Figure 12).

Seasonal ranges of activity were greater in Brownlee Reservoir than in the riverine section below Swan Falls dam. Median (0–1.4 mi) and maximum ranges (7.6–10.5 mi) were highest in Brownlee Reservoir during summer and fall seasons. Below Swan Falls, spring months showed the greatest activity by reproductive males and females in preparation for spawning although these movements were less than 5 mi (Figure 13a). Specific movement patterns and habitats used by spawning male and female sturgeon are discussed in Lepla and Chandler (2001). Individual fish movement patterns are provided in the appendices to this report.

4.2. Brownlee Dam–Hells Canyon Dam Reach

4.2.1. Population Abundance and Structure

A total of 2,913 setline hours and 32 gill net hours of effort was expended in Oxbow Reservoir during 1998 (Table 1). We captured no sturgeon in this pool with our gear; however, six sturgeon have died in the Brownlee tailrace from 1994 to 2001, indicating that some sturgeon still inhabit this reach although at very low numbers. A few sturgeon carcasses showed signs of external injury that presumably occurred when the fish swam upstream into the draft tube. This type of injury has been observed below C.J. Strike Dam after sturgeon entered draft tubes while the units were not operating. The fish were then injured either by blade strikes as the unit began operating or by coming into contact with the concrete walls as they left the draft tube.

In Hells Canyon Reservoir, a total of 2,690 setline hours and 39 gill net hours of effort was expended to capture 4 sturgeon (Table 1). Three wild adult sturgeon and one juvenile hatchery

Page 8 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon sturgeon were caught with setline gear near the upper end of Hells Canyon Reservoir, between RM 263.4 and 269.9 (Figure 3 and Figure 4). The wild sturgeon ranged from 139 to 250 cm TL, while the hatchery fish measured 63 cm TL. We captured no wild juvenile sturgeon in this reach (Figure 6b); the youngest fish was 13 years old (Table 3). Mean length-at-age showed relatively good growth rates (Figure 8a), and the mean relative weight was 93% of the standard for white sturgeon (Figure 10b). No VBG function or mortality rates were estimated for sturgeon in this reach because of the small sample size.

4.2.2. Telemetry

Two female sturgeon ranging in maturity from late vitellogenic to ripe and one white sturgeon of unknown sex were tagged with radio and sonic transmitters between Oxbow and Hells Canyon dams in 1998. Fish lengths ranged from 139 to 250 cm TL and were at large from 417 to 479 days during our tracking efforts. Total distance traveled during monitoring ranged from 45.3 to 92.3 mi (Table 6). However, the farthest distance sturgeon traveled from their initial capture locations ranged from 11.1 to 15.9 mi with an average of 4 mi during the entire period of monitoring (Figure 11b). Seasonal range of activity was highest during summer and fall periods although some movement between tracking events occurred throughout spring and winter periods (Figure 13b). Individual fish movements are presented in the appendices to this report. Habitat conditions and spawning related behavior of the female sturgeon are described in Lepla and Chandler (2001).

4.3. Hells Canyon–Lower Granite Reach

4.3.1. Population Abundance and Structure

Expending 27,658 hours of setline and 681 hours of angling effort, we caught 923 white sturgeon, which included 270 recaptures, between Granite Rapids (RM 238) and the mouth of the Salmon River (RM 188). The majority of sturgeon (90%, n = 843) were captured using setline gear, while 80 sturgeon were caught by supplemental angling (Table 1). The distribution of sturgeon above the Salmon River was relatively consistent upstream to Granite Rapids (Figure 3), with the highest catch rates occurring upstream of RM 217 (Figure 4). We did no sampling between Granite Rapids and Hells Canyon Dam (RM 247.6) because of safety concerns associated with navigating Granite and Wild Sheep rapids. Downstream of the Salmon River confluence to Lower Granite Dam, a total of 876 sturgeon (including 106 recaptures) were sampled by the Nez Perce Tribe from 1997 through 2000 (Tuell and Everett 2001) (Table 1). The highest number of sturgeon sampled in this section occurred between RM 188 and 159 (Figure 3).

Using the Schnabel method, we estimated the abundance of sturgeon greater than 70 cm TL in the reach upstream of the Salmon River at 1,312 individuals (95% CI 1,010–1,868). The open population estimator yielded a similar point estimate (n = 1,600), but with considerably larger bounds (95% CI 617–9,471). Tuell and Everett (2001) estimated the abundance of similar-sized sturgeon downstream of the Salmon River at 2,313 (95% CI 2,040–2,668) individuals. Combining the abundance indices from our survey (1,312) and the Tuell and Everett survey

Hells Canyon Complex Page 9 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company yielded a population estimate of 3,625 individuals greater than 70 cm TL, or 28 fish/river mile in the Hells Canyon–Lower Granite Reach (Table 2).

White sturgeon upstream of the Salmon River ranged in length from 52 to 291 cm TL. A length-frequency histogram showed that 56% of the sturgeon captured with setlines were less than 92 cm TL, 25% were between 92 and 183 cm TL, and 19% were greater than 183 cm TL (Figure 6c). We found sturgeon at least 70 cm TL in size between Swan Falls Dam and the Salmon River fully recruited to all setline hooks (Figure 14). Combining these data with length data from sturgeon caught by Tuell and Everett (2001) downstream of the Salmon River using setline and angling showed similar percentages among the three size groups for the entire reach (Figure 6d and Figure 15).

We assigned ages ranging from 3 to 45 years to 247 sturgeon caught between Hells Canyon and Lower Granite dams. Annual mortality (A) and survival (S) rates for sturgeon caught upstream of the Salmon River were 0.13 and 0.87, respectively, for ages 6 to 13. Rate estimates from Tuell and Everett (2001) for the entire population between Hells Canyon and Lower Granite dams were 0.04 (A) and 0.96 (S) (Table 7). Tuell and Everett (2001) also developed the VBG function Lt = 296 {1 – e [–0.0479 × (t + 0.659)]} to describe length-at-age for sturgeon in the reach between Lower Granite and Hells Canyon dams (Figure 8a). Paired length and weight measurements of sturgeon throughout the reach were used to develop the length-weight equation: Wt = 3.42E-06 TL3.094 (Figure 9a) (Tuell and Everett 2001). Mean relative weight for sturgeon in Lower Granite Reservoir (95%) was higher than relative weight of fish sampled in the river upstream of the pool (87%). The mean relative weight for all sturgeon sampled between Hells Canyon and Lower Granite dams was 88% of the standard weight (Figure 10c).

We surgically examined 82 sturgeon greater than 150 cm TL to determine sex and stage of maturity. Of these fish, we identified 57% as female (n = 47) and 43% as male (n = 35), yielding a 1.3:1 female to male ratio. The distribution of females in various stages of maturity was 72% previtellogenic, 11% early vitellogenic, 2% late vitellogenic, 4% ripe, 7% spent, and 4% previtellogenic with attritic oocytes. The reproductive potential of female sturgeon was estimated at 11%. As for males, 9% were reproductive (Table 4). We estimated the number of spawning females (> 150 cm TL) inhabiting the reach upstream of the confluence of the Salmon and Snake rivers at 20 (95% CI 15–29). Adding the population data collected downstream of the Salmon River by the Nez Perce Tribe, we estimated the number of female spawners for the entire reach at 56 (95% CI 47–70).

4.3.2. Telemetry

A total of 21 sturgeon—comprising 9 females ranging in maturity from previtellogenic to spent, 8 males from nonreproductive to mature, and 4 fish of unknown sex—were tagged with radio and sonic transmitters between Hells Canyon Dam and the Salmon River between 1997 and 2000. Fish lengths ranged from 138 to 272 cm TL, and fish were at large from 85 and 910 days. Total distance traveled during monitoring ranged from 0.3 to 96.3 miles (Table 8). The range of movement activity was fairly localized, with the majority (73%) of sturgeon traveling less than 10 mi from their initial capture locations. Average distance traveled by all fish during our monitoring was 1.2 mi. Only two female sturgeon and one fish of unknown sex showed more

Page 10 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

extensive movements between 24 and 60.7 mi (Figure 11c). The movement activity by the female sturgeon was associated with post-spawning behavior and is described in detail by Lepla and Chandler (2001). Overall, seasonal range of activity was low for all periods, although spring and summer months had the greatest maximum distances traveled, which was primarily a result of post-spawning behavior (Figure 13c). Individual sturgeon movements are presented in the appendices to this report.

5. DISCUSSION

5.1. Swan Falls–Brownlee Reach

White sturgeon populations associated with the HCC vary from an abundant, reproducing population below Hells Canyon Dam to reaches between Hells Canyon and Swan Falls dams with few fish and little or no detectable recruitment. Comparing the current status of sturgeon with earlier IDFG studies has shown that sturgeon abundance between Hells Canyon and Swan Falls dams has changed little over the past 30 years. In the uppermost reach between Swan Falls and Brownlee dams, several surveys have reported low captures of sturgeon ranging from 1 (Cochnauer 1983, Kruse-Malle 1993) to 25 (Reid et al. 1973) to 42 sturgeon (Reid and Mabbot 1987). Reid and Mabbot (1987) estimated the population of sturgeon greater than 100 cm TL between Swan Falls Dam and Walters Ferry at 137 to 173, an estimate that is comparable to our current estimate of 155 individuals. Cochnauer (1983) concluded that this population was depressed in abundance and had been reduced since the early 1970s. Will Reid (IDFG, pers. comm. to Cochnauer, 1983) hypothesized that increased fishing resulting from the stocking of channel catfish may have contributed to illegal harvest and mortality of sturgeon in this reach.

The majority of sturgeon was sampled between Swan Falls Dam and Walters Ferry. The quality of habitat from Walters Ferry to Brownlee Reservoir might explain the skewed distribution of sturgeon toward the upper end of this reach. Although there are intermittent deep pools between Walters Ferry and the top of Brownlee Reservoir, much of this section of river consists of relatively shallow runs and braided channels associated with island complexes. No sturgeon were sampled in similar types of river habitats in the Bliss to C.J. Strike reach, where a sizeable population of sturgeon exists (Lepla and Chandler 1995). Poor water quality in the lower section of this reach may also contribute to skewed distribution of sturgeon toward the top of this reach. Average summer water temperatures below Swan Falls Dam (23.2 °C) are several degrees cooler than the lower river near Weiser, Idaho (25.5 °C) (Figure 16). White sturgeon are considered a cool/coldwater species and are better suited to water temperatures below 25 °C. Low dissolved oxygen levels are also not a problem below Swan Falls Dam, although they often occur in Brownlee Reservoir during summer months.

Size composition has also remained similar to results in previous studies (Reid et al. 1973, Reid and Mabbot 1987), with sturgeon greater than 92 cm TL dominating both current and past length-frequency histograms. From 1986 to 1987, the size composition of sturgeon sampled between Swan Falls and Brownlee dams broke out to about 3% less than 92 cm, 23% between 92

Hells Canyon Complex Page 11 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company and 183 cm, and 74% greater than 183 cm, which closely resembled our 1996 to 1997 length- frequency data (Figure 17). In addition, results from a 1995 IDFG mail survey for sturgeon anglers also showed a similar trend. These results reported only 7% of the sturgeon as measuring less than 92 cm (IDFG 1996), a finding that supports our observations of poor recruitment. While Lepla and Chandler (2001) have documented spawning in this reach and the continuing presence of small sturgeon indicates that some recruitment is still occurring in this population, our estimate of available female spawners was very low (n = 7, 95% CI 3–29). This estimate suggests that near future recruitment will probably also remain low, perhaps below the levels necessary to sustain this population.

The VBG functions suggested that growth rates of sturgeon—primarily represented by fish captured between Swan Falls and Walters Ferry—was slightly lower as fish exceeded 140 cm than the growth rates for sturgeon downstream of Hells Canyon Dam. However, this finding was likely an artifact of small sample size (n = 21) from the Swan Falls–Brownlee reach. When comparing weight-length relationships and relative weights, our observations indicated that they were very similar to those for sturgeon between the Swan Falls–Brownlee and Hells Canyon−Lower Granite reaches. In fact, the condition factor of sturgeon downstream of Swan Falls Dam might not have changed appreciably since the last IDFG survey. Reid et al. (1973) reported anglers capturing a large sturgeon (296 cm TL) weighing 163 kg, which translated into a relative weight of 86%. Although one observation precludes any meaningful conclusion, this observation is comparable to the current estimate of 87%. Interestingly, when comparing relative weights of sturgeon captured only in Snake River reservoirs, we found that sturgeon captured in Brownlee Reservoir (82%) had a significantly lower condition factor (P = 0.005) than white sturgeon in Bliss (98%), Oxbow (93%), and Lower Granite reservoirs (95%). Typically, we observe higher mean relative weights of sturgeon sampled from Snake River reservoirs than those from riverine sections. This finding is likely due to less energetic demand to sturgeon of inhabiting slack-water environments, or perhaps food resources are more available. However, this higher mean relative weight was not the case with sturgeon in Brownlee Reservoir. In fact, these fish had a lower mean relative weight than those of sturgeon from riverine sections (Table 9).

We believe poor water quality in the lower segment of this reach is the primary factor contributing to the low condition factor. Cech et al. (1984) described significantly reduced growth rates for juvenile white sturgeon under hypoxia, probably resulting from reduced feeding activity. Brownlee Reservoir experiences severe water quality degradation during dry and normal water years because of nutrient influxes from agricultural activity and municipal wastes from the surrounding watersheds. During years with low river flows, water quality that is lethal to sturgeon can comprise 80% of the bottom 2 m in Brownlee Reservoir (Lepla and Chandler 2001). In fact, water quality-related sturgeon mortalities have occurred in Brownlee Reservoir during low-flow water years. In mid-July 1990, lethal dissolved oxygen conditions (less than 1 mg/l), and possibly exacerbated by high water temperatures (25–26 °C), caused the deaths of at least 28 adult white sturgeon near the upper end (RM 324) of Brownlee Reservoir. Peak summer water temperatures in the Snake River upstream of Brownlee Reservoir near Weiser, Idaho, can also reach 27 °C. In Brownlee Reservoir, peak water temperatures near the surface (at depths of less than 1 m) during July and August can range from 24.4 to 31 °C, which is likely within the upper lethal limits (28–30 °C) for white sturgeon. While the actual upper lethal temperature limit

Page 12 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

is unknown, S. Doroshov (UC Davis, pers. comm.) suggested our assumption of 28 to 30 °C to be accurate.

A Population Viability Analysis (PVA) of factors controlling white sturgeon recruitment in the Snake River showed that water quality was the primary factor limiting sturgeon between Swan Falls and Hells Canyon dams and that reestablishment of recruitment would not be attainable unless water quality were improved (Jager et al. 2001). Jager et al. (2001) also stressed the need for further study regarding poor water quality and its effect on sturgeon given that the tolerances of juvenile and adult white sturgeon and the ability of all ages to avoid poor habitat are not well known. Water quality-related factors other than low dissolved oxygen and high temperatures may also be affecting reproductive success in this reach. Studies conducted in the Kootenai River highlighted the bioaccumulation of contaminants from food chain organisms, water, and sediment that could stress reproductive capabilities of white sturgeon. Study results also showed very high mortality of incubating sturgeon eggs coated with suspended solids when reared in unfiltered water from the Kootenai River. Organic matter and contaminants from suspended solids and river water were likely the primary sources of bacteria and fungi that contributed to the low survival of embryos (Kruse 2000). These water quality conditions may also be a significant factor affecting recruitment in the Swan Falls–Brownlee reach given the high organic loads occurring in this segment of the Snake River. Further study evaluating effects of poor water quality on early life stages of sturgeon and thus recruitment success in the sturgeon population in this reach may be prudent.

5.2. Brownlee–Oxbow–Hells Canyon Reaches

The study area reaches in which we caught the fewest sturgeon (0–4) were below Brownlee and Oxbow dams. The capture of few adults and the absence of small or young sturgeon suggested that no recruitment has occurred recently or, at least, that any recruitment was undetectable by our gear. The status of white sturgeon in Oxbow and Hells Canyon reservoirs appears unchanged since the earlier IDFG surveys. Welsh and Reid (1971) concluded that, although anglers have captured sturgeon in the tailrace of Brownlee Dam, the species is probably not abundant in Oxbow Reservoir and probably not present in Hells Canyon Reservoir.

The Brownlee–Oxbow and Oxbow–Hells Canyon reaches are two relatively short river segments in the Snake River. In reaches associated with both the Hells Canyon three-dam complex and the mid-Snake three-dam complex (Upper Salmon Falls, Lower Salmon Falls, and Bliss), we observed little or no detectable presence of sturgeon. Not only does the relatively close spacing of adjacent dams limit the amount of available habitat, but the short distance between dams probably contributes more to downstream losses of sturgeon than do longer reaches, particularly for sturgeon in early life stages. White sturgeon larvae are planktonic and can drift long distances in river currents. Brannon et al. (1986) reported that the dispersal phase might last up to six days. McCabe and Tracy (1993) and Kohlhorst (1976) have found sturgeon larvae about 115 to 121 mi downstream of known egg incubation and probable spawning sites. Similarly, the potential for sturgeon larvae to disperse great distances in the Snake River was highlighted by the capture of a larval sturgeon in Brownlee Reservoir (RM 309.5) during 1997 efforts by IPC (Lepla and Chandler 2001). While the spawning origin of this larva was uncertain and it may have

Hells Canyon Complex Page 13 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

originated immediately upstream of Brownlee Reservoir (RM 340), known spawning events have been documented 144 mi upstream near the upper end of this reach.

A simulation study of factors controlling white sturgeon recruitment in shorter segments of the Snake River, including Oxbow and Hells Canyon reservoirs, indicated that larval export was a key factor in limiting simulated recruitment (Jager et al. 2000, 2001). In addition, both reservoirs sometimes experience severe water quality conditions, particularly during low-flow years, when they receive anoxic water from Brownlee Reservoir. During low-flow years, low dissolved oxygen levels that are lethal to sturgeon can comprise 55 to 73% of the bottom 2 m in Oxbow and Hells Canyon reservoirs (Lepla and Chandler 2001).

5.3. Hells Canyon–Lower Granite Reach

While the status of white sturgeon upstream of Hells Canyon Dam may not have improved over the past 30 years, the sturgeon population below Hells Canyon Dam has shown positive changes, particularly in size composition. Juvenile fish less than 92 cm TL continue to dominate the population, and size groups greater than 92 cm TL have steadily grown since the 1970s. The percentage of middle-sized sturgeon (92–183 cm TL) has increased from 4%, as sampled from 1972 to 1975 (Coon et al. 1977), to 18%, as sampled from 1982 to 1984 (Lukens 1985), to 29%, as sampled from 1997 to 2000. Similarly, larger sturgeon (> 183 cm TL) has also increased from 2%, as sampled from 1982 to 1984, to 18%, as sampled from 1997 to 2000 (Figure 18). The positive changes in size composition have been attributed primarily to the population’s recovery from the effects of catch-and-keep fishing regulations for fish 92 to 183 cm long (Cochnauer 1985).

Fishing regulations banning commercial fishing in the Snake River in Idaho were first adopted in 1943 (PSMFC 1992). No annual limits were set for sport harvest until 1956, when angler possession was limited to two sturgeon greater than 102 cm long per year. Size limits became increasingly restrictive. Beginning in 1960, restrictions permitted anglers to keep only sturgeon between 92 and 183 cm long. Although the minimum size was smaller, anglers were no longer allowed to keep fish larger than 183 cm. By 1970, catch-and-release regulations were enforced for the entire Snake River in Idaho. Based on recent survey data, the sturgeon population below Hells Canyon Dam appears to have responded well from reduced harvest.

The population currently provides a catch-and-release sport fishery (including incidental angling mortality) and harvest by the Nez Perce Tribe. Overall, the current sturgeon population below Hells Canyon is genetically diverse and exhibits a healthy population structure, based on the current stock structure dominated by juveniles, wide range of size classes, and stages of maturity from immature juveniles to reproductive adults. This current size structure closely resembles IDFG’s desired management goal of 60% of the population measuring between 60 and 90 cm TL, 30% measuring between 90 and 180 cm TL, and 10% measuring greater than 180 cm TL.

A comparison of the length-weight relationships from our research with data from previous surveys by Coon et al. (1977) and Lukens (1985) showed that regression lines were relatively similar, although a visible shift toward lighter fish at the larger sizes was apparent (Figure 9b). Interpreting the biological significance of this shift is difficult given that, when compared, the

Page 14 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

mean relative weights among these studies were not significantly different (P = 0.082, F = 2.51, df = 2). In fact, mean relative weights for the sturgeon population below Hells Canyon Dam have remained essentially unchanged: 90% from 1972 to 1975 (Coon et al. 1977), 89% from 1982 to 1984 (Lukens 1985), and 89% from 1997 to 2000. This stability in mean relative weights suggests that the sturgeon condition has not declined since the sampling period from 1972 to 1975 (Table 9). According to Hoefs (1998), the shift in length-weight relationships toward lighter fish at the larger sizes is the result of too few sturgeon greater than 183 cm being captured, which significantly affected the relationships. For instance, only 2% of the sturgeon captured by Lukens (1985) were greater than 183 cm. Hoefs (1998) also suggested that inferences about changes in the condition of the sturgeon population should be based only on total population responses.

Growth rates of sturgeon below Hells Canyon appear to have increased since the earlier surveys by Coon et al. (1977) and Lukens (1984), particularly for sturgeon less than 20 years old (Figure 8b). Coon (1978) reported reduced growth rates for juvenile sturgeon between the ages of 6 and 12 years, averaging only 3.3 cm per year, while the latest growth rates averaged 9 cm per year based on the VBG relationship. Coon (1978) speculated that the sturgeon below Hells Canyon Dam showed reduced growth rates because these sturgeon reside in a less productive environment than sturgeon populations that have access to marine environments. However, there is still no clear explanation for this change in recent growth rates. The previous surveys also estimated higher numbers of sturgeon in the Hells Canyon–Lower Granite reach (8,000–12,000, Coon et al. 1997; 4,275, Lukens 1985) compared with our estimate of 3,625. However, given the difference in estimation techniques, directly comparing these values warrants caution.

The survival rates for sturgeon below Hells Canyon Dam are comparable with those for several other white sturgeon populations in the Snake River and do not appear to be cause for concern (Table 7). Slight differences in rate estimates are probably a result of random error associated with sampling or aging techniques. Population simulations using mortality rates as high as 27% still predicted an increase in abundance of white sturgeon over time in the population in the Bliss–C.J. Strike reach (Cochnauer 1983).

The reproductive potential (11%) of female white sturgeon below Hells Canyon Dam was also comparable with the reproductive potential (13%) of females in the sturgeon population below Bliss Dam, the second largest sturgeon population in the Snake River above HCC (Lepla and Chandler 1995). Overall, only a small portion (10–20%) of white sturgeon populations is believed to be reproductive in any year (Apperson and Anders 1990).

The results of a study of the genetic composition of Snake River white sturgeon have been described by Anders et al. (2000) in Assessing Genetic Variation Among Columbia Basin White Sturgeon Populations. In summary, Anders et al. (2000) found no evidence of distinct differences among sturgeon populations in the Columbia and Snake rivers. While some clinal variation for reduced haplotype diversity was found in populations with increasing distance upstream in the basin, the correlation was neither strong nor an accurate predictor of white sturgeon haplotype diversity. In fact, the same clinal variation was observed in the sturgeon population in the Fraser River in British Columbia, which is an unimpounded system. Both AMOVA analysis and a haplotype network diagram found little geographic population

Hells Canyon Complex Page 15 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

structuring of white sturgeon in western North America. Except for the Kootenai River sturgeon population, considerable genetic diversity remains in all of the Columbia and Snake rivers sturgeon populations, particularly in Snake River populations below Hells Canyon and Bliss dams. The authors noted that, while bidirectional gene flow has probably been reduced—or eliminated in some cases—since the construction of dams, white sturgeon populations throughout the Columbia River Basin currently remain large enough to counteract deleterious effects.

5.4. Telemetry

Species in the order Acipenseriformes migrate for two basic reasons, feeding (rearing) and reproduction. Upstream migrations are usually associated with spawning activities while downstream migrations are associated with feeding (Bemis and Kynard 1997). However, there are considerable variations in the migration patterns of sturgeon species, including white sturgeon. In the lower Columbia River, seasonal distribution patterns of white sturgeon suggest a general upstream migration in the fall, a quiescent winter period, downstream migration in the spring, and large congregations of sturgeon in the estuary during summer. DeVore and Grimes (1993) suggested that these migration patterns were a result of ephemeral food availability. However, Bajkov (1949) found that some white sturgeon appeared to not migrate at all during a particular year. North et al. (1993) also reported variations in movement patterns of white sturgeon in three Columbia River reservoirs above Bonneville Dam. Of the sturgeon sampled, half the fish moved downstream after release while the other 50% moved upstream. Most sturgeon moved at least 0.6 river miles, with some individuals traveling up to 94 mi.

Similar variations among movement patterns were observed for telemetered white sturgeon in the Snake River between Swan Falls Dam and the Salmon River. Several sturgeon at large between 193 and 648 days traveled distances totaling 73 to 96 mi, while others at large for similar durations (185–679 days) traveled less than 10 mi. While sturgeon are capable of traveling great distances, much of this distance was “accumulated” by individuals traveling between areas of close proximity. Overall, the range of movement activity between Swan Falls and the Salmon River was fairly localized, with the majority (73%) of fish traveling less than 10 mi from their initial capture locations. The average distance traveled by all sturgeon during our monitoring efforts was less than 4 mi. Coon (1978) observed similar localized movement patterns by sturgeon greater than 183 cm below Hells Canyon; these fish often moved only between pools in close proximity. He noted that smaller sturgeon tended to move downstream but averaged only around 4.3 mi per year. Similar ranges in movement activity have also been observed in other Snake River reaches between Swan Falls and Bliss dams (Wittmann-Todd et al. 2001).

In general, sturgeon in reservoirs showed more movement between tracking events than fish residing in free-flowing sections of the Snake River. Sturgeon in Oxbow and Brownlee reservoirs often traveled within the middle and upper sections of the pool while fish movement in the free-flowing sections below Swan Falls and Hells Canyon dams was more localized. Lepla and Chandler (1995) speculated that these similar types of movement patterns observed in the Bliss–C.J. Strike reach was related to the different feeding behaviors between riverine and reservoir areas. In free-flowing sections, food items carried by the river currents could settle out

Page 16 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

in habitats used by sturgeon, but acquiring food items in a reservoir required a more active searching behavior.

RL& L (2000) reported similar movement behavior for white sturgeon in the Fraser River, an undammed river system. Telemetry observations of female and male white sturgeon in various stages of maturity and segments of the Fraser River showed mean movements between 0.4 and 3.3 river miles for Stock Group 1 (SG1), 0 to 1.8 river miles for SG2, 0.2 to 6.7 river miles for SG3, and 0.06 to 0.4 river miles for SG5. The authors also noted that several sturgeon exhibited extensive movements that exceeded 25 river miles and in some cases were more than 43 river miles between tracking events. Overall, localized movements of less than 6 river miles were most common during their telemetry studies, a result suggesting that discrete sections of the Fraser River provided suitable habitats for several life history functions. Among the sturgeon population of the Nechako River, a tributary to the Fraser River, extended movements of more than 9 river miles were common (maximum movements ranged in direction from 38 river miles upstream to 45 river miles downstream) and thought to be an adaptation of feeding strategy to exploit the sockeye salmon migration through this system during the summer. Similar large-scale movements that appear to be necessary because of the geographic separation between suitable habitats required for various life functions, such as feeding, spawning, and overwintering, have also been observed in other river systems, such as the Kootenai River (Apperson and Anders 1991) and Lake Roosevelt (Brannon and Setter 1992).

Overall, movement activity of telemetered sturgeon in the Snake River was not markedly different between seasons. We did not observe what could be considered a “seasonal migration” by telemetered sturgeon seeking seasonal feeding or rearing habitats within reaches. However, given sturgeon are long lived, some if not most sturgeon likely will move between various habitats throughout the entire length of a particular reach over the course of many years. For instance, we have observed large-scale movement over extended periods by some sturgeon in the Bliss–C.J. Strike reach. In particular, nine sturgeon originally PIT-tagged in C.J. Strike Reservoir during 1989−1992 were later recaptured 50 to 62 mi upstream near the upper stretch of the reach. The time between captures of these fish ranged between 1 to 8 years. However, similar to our telemetry observations, the majority (50–97%) of PIT-tagged sturgeon were also recaptured within 10 mi of their original release locations over similar time periods (Figure 19).

The most notable movement patterns in the Snake River are generally associated with spawning, and the distance traveled depends on the proximity of suitable spawning habitat (Lepla and Chandler 2001, Wittmann-Todd et al. 2001). These patterns are particularly evident among sexually mature sturgeon traveling from reservoir to riverine environments to spawn. In C.J. Strike Reservoir, located 37 miles upstream of Swan Falls Dam, reproductive adults often left the pool as spawning temperatures approached and, depending on their capture location in the pool, traveled about 16 river miles upstream of the pool to stage and spawn near RM 521.8. Similar upstream spawning movements, although typically less than a few miles, were observed among sturgeon below C.J. Strike and Oxbow dams as they sought suitable spawning conditions that generally occurred only near the tailraces.

Spawning-related movements in the river canyon corridors below Swan Falls, Hells Canyon, and Bliss dams (located 102 mi upstream of Swan Falls) were generally less defined. These river sections contain numerous pools for staging, as well as nearby high-velocity runs and rapids for

Hells Canyon Complex Page 17 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company spawning. The distances that spawners traveled varied between 0.3 and 9.0 river miles between King Hill and Bliss Dam, 1.5 to 6.0 river miles below Swan Falls Dam, and 0.0 to 2.0 river miles below Hells Canyon Dam. None of the spawners in these river segments traveled upstream to the dam tailraces. Post-spawning movement activity was also variable: some individuals traveling between 13 and 61 mi while others showed no discernable movement at all (Lepla and Chandler 2001, Wittmann-Todd et al. 2001). Overall, the predominantly localized movement behavior by reproductive and nonreproductive sturgeon suggested that several sections of the Snake River, particularly in reaches below Bliss, Swan Falls, and Hells Canyon dams, provide suitable habitat for several life history functions that include feeding, rearing, overwintering, and spawning.

6. SUMMARY AND CONCLUSIONS

6.1. Swan Falls–Brownlee Reach

Based on the sampling we conducted throughout the study area, the status of the white sturgeon population in the Swan Falls to Brownlee Dam reach is poor. Catch rates and overall numbers of sturgeon sampled in this reach were very low, with most fish captured near the upper end of the reach between Swan Falls and Walters Ferry. Recruitment levels appear to have remained poor since earlier IDFG surveys, and the population consisted primarily of subadult and adult sturgeon, with few fish less than 92 cm TL. The continuing presence of some small sturgeon indicates that some recruitment is occurring but at low levels. The averaged relative weights for all sturgeon captured in this reach were similar to those for the Hells Canyon population; however, sturgeon in Brownlee Reservoir had a significantly lower condition factor than other sturgeon in Snake River reservoirs. Severe water quality degradation, particularly in the lower river and Brownlee Reservoir, appears to be limiting white sturgeon in this reach. The presence of a small population currently composed of predominantly mature adults, few new recruits, and few annual spawners suggests that future recruitment will remain low, perhaps below the levels necessary to sustain the population.

6.2. Brownlee–Hells Canyon Reach

The status of the white sturgeon population in the reaches between Brownlee and Hells Canyon dams is poor and appears not to have changed over the past 30 years since few wild white sturgeon remain in either pool. The capture of only three adult sturgeon in Hells Canyon Reservoir suggested that opportunities for reproduction are infrequent. The absence of small sturgeon also indicated that no recent recruitment has occurred. Simulated recruitment for white sturgeon in Oxbow and Hells Canyon reservoirs indicated that recruitment was limited by larval export, spawner limitations, and poor water quality.

Page 18 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

6.3. Hells Canyon–Lower Granite Reach

The sturgeon population between Hells Canyon and Lower Granite dams is the largest population in the Snake River upstream of Lower Granite Dam. Juvenile fish less than 92 cm TL continue to dominate the population, and size groups greater than 92 cm TL have steadily increased since the 1970s. Survival estimates were similar to rates observed in several Snake River populations, and the trend of mean relative weights showed that fish condition has not declined since earlier surveys conducted from 1972 to 1975 and from 1982 to 1983. Reproductive readiness of female sturgeon was also comparable with reproductive readiness typically expected in white sturgeon populations. The current sturgeon population below Hells Canyon is genetically diverse and exhibits a healthy population structure, based on the current stock structure dominated by juveniles, wide range of size classes, and stages of maturity from immature juveniles to reproductive adults.

6.4. Telemetry

A total of 35 white sturgeon—comprising 9 females (ranging in maturity from previtellogenic to spent condition), 10 males (ranging in maturity from nonreproductive to reproductive condition) and 5 fish of unknown sex—were fitted with radio and sonic transmitters between Swan Falls Dam and the mouth of the Salmon River. These fish ranged in lengths from 139 to 276 cm TL and were at large from 85 to 910 days during our tracking efforts. Total distance traveled by sturgeon during our monitoring efforts ranged from 0.9 to 96.3 mi; however, the overall range of movement activity was fairly localized, with 73% of the fish in the Swan Falls–Brownlee and Hells Canyon–Salmon River reaches traveling less than 10 mi from their initial capture locations. The farthest distance traveled by sturgeon in the Oxbow–Hells Canyon reach (from their initial capture locations) was 11.1 to 15.9 mi. The average distance traveled by all sturgeon during our monitoring efforts ranged from 0.4 to 4 mi. In general, sturgeon in reservoirs showed more movement between tracking events than fish residing in free-flowing sections of the Snake River. Sturgeon in Oxbow and Brownlee reservoirs often traveled within the middle and upper sections of the pool, while fish movement in the free-flowing sections below Swan Falls and Hells Canyon dams was more localized. We speculated that this type of movement behavior was related to the different feeding behaviors between riverine and reservoir areas. In free-flowing sections, food items carried by the river currents could settle out in habitats used by sturgeon while acquiring food items in a reservoir required a more active searching behavior. Overall, movement activity did not differ markedly between seasons. The most notable movement patterns in the Snake River are generally associated with spawning, and the distance traveled varied, depending on proximity of suitable spawning habitat. The predominantly localized movement behavior by white sturgeon suggested that several sections of the Snake River, particularly in reaches below Swan Falls and Hells Canyon dams, provide suitable habitat for several life history functions that include feeding, rearing, overwintering, and spawning.

Hells Canyon Complex Page 19 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

7. ACKNOWLEDGMENTS

Special thanks to Tim Stuart, John Anderson, Mike McLeod, and Stephanie Eisenbarth for their tireless efforts to complete our white sturgeon surveys associated with the HCC. We also extend thanks to Dr. Dennis Scarnecchia for preparing and aging our white sturgeon fin sections and Mike Tuell and Scott Everett of the Nez Perce Tribe for providing data for sturgeon below the Salmon River.

8. LITERATURE CITED

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Apperson, K., and P. J. Anders. 1990. Kootenai River white sturgeon investigations and experimental culture. Annual Progress Report FY 1990. Idaho Department of Fish and Game and Bonneville Power Administration, Portland, OR. Contract DE-AI79-88BP93497, Project 88-65.

Bajkov, A. D. 1949. A preliminary report on the Columbia River sturgeon. Fisheries Commission of Oregon, Portland. Research Briefs 2(2):1-8.

Beamesderfer, R. C. 1993. A standard weight (Ws) equation for white sturgeon. In: R. C. Beamesderfer and A. A. Nigro, editors. Volume II. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final Report. Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Beamesderfer, R. C., J. C. Elliott, and C. A. Foster. 1989. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. In: A. A. Nigro, editor. Report A. Annual Progress Report. Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Beamesderfer, R. C., and B. E. Rieman. 1988. Size selectivity and bias in estimates of population statistics of smallmouth bass, walleye, and northern squawfish in a Columbia River reservoir. North American Journal of Fisheries Management 8:505-510.

Bemis, W. E., and B. Kynard. 1997. An introduction to acipenseriform biogeography and life history. Environmental Biology of Fishes 48:167-183.

Page 20 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Brannon, E., A. Setter, M. Miller, S. Brewer, G. Winans, F. Utter, L. Carpenter, and W. Hersberger. 1986. Columbia River white sturgeon (Acipenser transmontanus) population genetics and early life history. Bonneville Power Administration, Portland, OR. Contract DE-AI79-84BO18952, Project 83-316.

Brannon, E., and A. Setter. 1992. Movements of white sturgeon in Lake Roosevelt. Final Report 1988–1991. Prepared for: U.S. Department of Energy and the Bonneville Power Administration, Division of Fish and Wildlife, Portland, OR. Project 89-44. 35 p.

Cech, J. J., Jr., S. J. Mitchell, and T. E. Wragg. 1984. Comparative growth of juvenile white sturgeon and striped bass: effects of temperature and hypoxia. Estuaries 7:12-18.

Cochnauer, T. G. 1983. Abundance, distribution, growth and management of white sturgeon (Acipenser transmontanus) in the middle Snake River, Idaho. Doctoral dissertation. University of Idaho, Moscow.

Cochnauer, T. G., J. R. Lukens, and F. E. Partridge. 1985. Status of white sturgeon, Acipenser transmontanus, in Idaho. In: P. P. Binkowski and S. I. Doroshov, editors. North American sturgeons. Dr. W. Junk Publishers, Dordrecht, Netherlands.

Conte, F. S., S. I. Doroshov, P. B. Lutes, and E. M. Strange. 1988. Hatchery manual for the white sturgeon Acipenser transmontanus with application to other North American Acipenseridae. Cooperative Extension, Division of Agriculture and Natural Resources, University of California, Davis. Publication 3322.

Coon, J. C. 1978. Movement, distribution, abundance and growth of white sturgeon in the mid-Snake River. Doctoral dissertation. Forest, Wildlife, and Range Experiment Station, University of Idaho, Moscow.

Coon, J. C., R. R. Ringe, and T. C. Bjornn. 1977. Abundance, growth, distribution and movements of white sturgeon in the mid-Snake River. Forestry, Wildlife and Range Experiment Station, Idaho Water Resources Research Institute, University of Idaho, Moscow. Contribution 97.

DeVore, J. D., and J. G. Grimes. 1993. Migration and distribution of white sturgeon in the Columbia River downstream from Bonneville Dam and adjacent marine areas, In: R. C. Beamesderfer and A. A. Nigro, editors. Volume I, Status and habitat requirements of white sturgeon populations in the Columbia river downstream from McNary Dam. Final Report. Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Edson, M., editor. 1956. The sturgeon story. Idaho Wildlife Review.

Harrison, J., S. Wells, R. Myers, S. Parkinson, and M. Kasch. 1999. 1999 status report on Brownlee Reservoir water quality and model development. Draft Technical Report. Idaho Power, Boise. 70 p.

Hells Canyon Complex Page 21 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Hoefs, N. J. 1998. Evaluation of potential means of rebuilding sturgeon populations in the Snake River between Lower Granite and Hells Canyon dams. 1997 Annual Report. Report to Bonneville Power Administration, Portland, OR. Contract 97-AM-30423, Project 00000333-00023 (9700900).

Hoelscher, B., and R. Myers. 2001. Tributary pollutant sources in the Hells Canyon Complex. In: Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise. Technical Report E.2.2-1.

Idaho Department of Fish and Game (IDFG). 1996. Sturgeon newsletter 4:1-4.

Jager, H. I., W. Van Winkle, K. Lepla, J. Chandler, and P. Bates. 2000. Population viability analysis of white sturgeon and other riverine fishes. Environmental Science and Policy 3:5483-5489.

Jager, H., K. Lepla, J. A. Chandler, W. Van Winkle, A. Sullivan, R. Myers, and M. Bevelhimer. 2001. Population viability model for Snake River white sturgeon. In: K. Lepla, editor. Chapter 3. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise. Technical Report E.3.1-6.

Kohlhorst, D. W. 1976. Sturgeon spawning in the Sacramento River in 1973, as determined by distribution of larvae. California Fish and Game 62(1):32-40.

Kruse, G. O. 2000. The effects of contaminants on reproduction, embryo development and related physiological processes in Kootenai River white sturgeon, Acipenser transmontanus Richardson. M.Sc. thesis. University of Idaho, Moscow.

Kruse-Malle, G. O. 1993. White sturgeon evaluations in the Snake River. Job Performance Report. Idaho Department of Fish and Game, Boise. Project F-73-R-15.

Lepla, K. B., and J. A. Chandler. 1995. A survey of white sturgeon in the Bliss reach of the middle Snake River, Idaho. In: Volume 1, Technical appendices for the Upper Salmon Falls, Lower Salmon Falls, and Bliss hydroelectric projects. Idaho Power, Boise. Technical Report E.3.1-E.

Lepla, K. B., and J. A. Chandler. 1997. Status of white sturgeon in the C.J. Strike reach of the middle Snake River, Idaho. In: Volume 1, Technical appendices for the C.J. Strike hydroelectric project. Idaho Power, Boise. Technical Report E.3.1-B.

Lepla, K.B., and J. A. Chandler. 2001. Physical habitat use and water quality criteria for Snake River white sturgeon. In: K. Lepla, editor. Chapter 2. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise. Technical Report E.3.1-6.

Lukens, J. R. 1984. Hells Canyon white sturgeon investigations. Job Performance Report. Idaho Department of Fish and Game, River and Stream Investigations, Boise. Project F-73-R-B.

Page 22 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Lukens, J. R. 1985. Hells Canyon white sturgeon investigations. Job Performance Report Idaho Department of Fish and Game, River and Stream Investigations, Boise. Project F-73-R-7.

McCabe, G. T., and C. A. Tracy. 1993. Spawning characteristics and early life history of white sturgeon Acipenser transmontanus in the lower Columbia River. In: R. C. Beamesderfer and A. A. Nigro, editors. Volume I, Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final Report. Bonneville Power Administration, Portland, OR. Contract DE-AI79-86BP63584.

Mosley, R., and C. Groves. 1990. Rare, threatened, and endangered plants and animals of Idaho. Natural Heritage Section, Idaho Department of Fish and Game, Boise.

Myers, R., S. Parkinson and J. Harrison. 1998. Tributary nutrient loadings to the Snake River Swan Falls to Farewell Bend, March through October 1995. Idaho Power, Boise. Technical Report AQ-98-HCC-001. 27 p.

Myers, R., and S. Pierce. 1999. Pollutant transport and processing in the HCC. Project Progress Report 1999. Idaho Power, Boise, ID. 26 p.

North, J. A., R. C. Beamesderfer, and T. A. Rien. 1993. Distribution and movements of white sturgeon in three lower Columbia River reservoirs. In: R. C. Beamesderfer and A. A. Nigro, editors. Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam. Final Report. Volume I. Bonneville Power Administration, Portland, OR. Contract No. DE-AI79-86BP63584.

Pacific States Marine Fisheries Commission (PSMFC). 1992. White sturgeon management framework plan. Prepared by the White Sturgeon Planning Committee, PSMFC, Portland, OR. 201 p.

RL&L Environmental Services Ltd. 2000. Fraser River white sturgeon monitoring program: comprehensive report 1995–1999. Final report prepared for: British Columbia Fisheries. RL&L Report 815F. 92 p. plus appendices.

Reid, W. W., and B. Mabbot. 1987. Regional fisheries management investigations, Region 3 (Boise) rivers streams investigations. Idaho Department of Fish and Game, Boise. Federal Aid to Fish Restoration Project F-71-R-11.

Reid, W. W., W. H. Goodnight, and B. B. Bowler. 1973. Survey of fish populations in the Snake River above Brownlee Reservoir. Idaho Department of Fish and Game, Boise, ID. Federal Aid to Fish Restoration Project F-63-R-2.

Ricker, W. E. 1975. Computation and interpretation of biological statistics of fish populations. Bulletin of the Fisheries Research Board of Canada 191.

SAS Institute, Inc. 1990. SAS/STAT user’s guide, version 6. 4th edition. SAS Institute, Cary, NC. 846 p.

Hells Canyon Complex Page 23 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Tuell, M. A., and S. R. Everett. 2001. Evaluation of potential means of rebuilding sturgeon populations in the Snake River between Lower Granite and Hells Canyon dams. 2000 Annual Report, Preliminary Draft. Report to Bonneville Power Administration, Portland, OR. Contract 97-AM-30423, Project 00000333-00023 (9700900).

Welsh, T. L., and W. W. Reid. 1971. Hells Canyon fisheries investigations. 1970 Annual Report. Idaho Department of Fish and Game, Boise.

Wittmann-Todd, S. W., M. R. Voskuilen, J. M. Etulain, S. Parkinson, and K. Lepla. 2001. Conceptual design for white sturgeon passage facilities at the Hells Canyon Complex. In: K. Lepla, editor. Chapter 4. Status and habitat use of Snake River white sturgeon associated with the Hells Canyon Complex. Technical appendices for Hells Canyon Complex Hydroelectric Project. Idaho Power, Boise. Technical Report E.3.1-6.

Page 24 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Table 1. Summary of effort and catch (including recaptures) for white sturgeon sampled in Snake River reaches from Swan Falls Dam to the mouth of the Salmon River.

Reach Year Gear Hours Catch CPUE Swan Falls–Brownlee 1996–97 Setline 16,752 32 0.002 Net 268 12 0.04 Angling 18 1 0.05 Totals 17,038 45

Brownlee–Oxbow 1998 Setline 2,913 0 0.00 Net 32 0 0.00 Totals 2,945 0

Oxbow–Hells Canyon 1998 Setline 2,690 4 0.001 Net 39 0 0.00 Totals 2,729 4

Hells Canyon-Salmon River 1997–00 Setline 27,658 843 0.03 Angling 681 80 0.117 Totals 28,339 923

1Salmon River–Lower Granite 1997–00 Setline — 429 - Angling — 77 - Net — 83 - N/A — 287 - Totals 876

1 Tuell and Everett 2001

Hells Canyon Complex Page 25 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Table 2. Abundance estimates for white sturgeon populations in Snake River reaches between Swan Falls Dam and Lower Granite Dam.

Population Estimate >70 Density Reach Year RM cm TL (95% CI) (fish/river mile) Swan Falls–Brownlee 1996–97 458–444 1155 11 (Walters Ferry) (70-621)

Brownlee–Oxbow 1998 284.6–273 — —

Oxbow Hells–Canyon 1998 273–247.6 — —

Hells Canyon–Salmon River 1997–00 238–188 21,600 32 (617–9,471) 238–188 31,312 26 (1,010-1,868)

4Salmon River–Lower Granite 1997–00 107–188 2,313 29 (2,040–2,668)

Lower Granite–Hells Canyon 1997–00 107–238 53,625 28 (3,050-4,536)

1 Population estimate in this reach represents sturgeon abundance from Swan Falls Dam (RM 458) to Walters Ferry (RM 444). 2 Open population estimator. 3 Closed population estimator. 4 Nez Perce Tribe sturgeon 1997–2000 survey data (Tuell and Everett 2001). 5 Population indices combined from IPC and Nez Perce Tribe sturgeon surveys.

Page 26 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Table 3. Mean length of white sturgeon 3 to 45 years old sampled in the Snake River from Swan Falls Dam to the mouth of the Salmon River.

Reach Age N Mean TL Range Swan Falls–Brownlee 9 1 110 — 10 1 120 — 12 2 101 88–101 14 1 197 — 15 2 178 164–191 17 1 169 — 18 1 142 — 19 4 151 98–196 20 1 149 — 25 1 237 — 26 1 163 — 31 1 236 — 32 1 275 — 37 2 254 217–290 45 1 276 —

Oxbow–Hells Canyon 13 1 139 — 21 1 236 — 23 1 250 —

Hells Canyon–Salmon River 3 1 74 — 4 3 68 64–70 5 14 74 52–94 6 13 84 74–133 7 8 80 71–106 8 9 87 78–114 9 6 105 86–119 10 11 99 73–164 11 8 96 84–108 12 8 117 91–143 13 3 120 73–147 14 1 132 — 15 3 151 134–186 16 2 184 172–196 17 1 174 — 18 1 186 — 20 3 184 178–192 21 1 189 — 22 4 212 182–227 25 1 178 — 26 1 206 — 28 3 198 151–232 30 2 228 220–236 31 1 233 — 42 1 253 — 45 1 232 —

Hells Canyon Complex Page 27 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Table 4. Stage of maturity of white sturgeon sampled in the Snake River from Swan Falls Dam (RM 458) to the mouth of the Salmon River (RM 188).

Category Swan Falls–Brownlee N (%) Oxbow–Hells Canyon N (%) HCD–Salmon N (%)

Female Previtellogenic 9 (53) — 34 (72) Early vitellogenic 5 (29) — 5 (11) Late vitellogenic 1 (50) 1 (2) Ripe 2 (12) 1 (50) 2 (4) Spent — — 3 (7) Previtellogenic with 1 (6) — 2 (4) attritic oocytes

Male Nonreproductive 4 (57) — 32 (91) Reproductive 3 (43) — 3 (9) Ripe — — —

Page 28 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Table 5. Summary of movement by telemetered white sturgeon in the Swan Falls−Brownlee reach of the Snake River.

From Initial Capture Initial Total Date Capture Days MaxDistance MaxDistance Mean Distance Tag Tagged Location at Downstream Upstream Movement Traveled Number1 Sex2 TL (cm) Stage3 (yymmdd) (RM) Large (river miles) (river miles) (river miles) (river miles) Swan Falls–Brownlee Reservoir S285 F 217 2 970814 327.8 439 10.9 0 1.5 24.7 S555 F 220 2 970821 327.8 241 10.5 0.0 2.0 20.3 S357 F 197 2 960917 331.6 334 10.4 2.7 2.1 34.3 S3434 M 162 8 970708 326.6 475 7.5 3.3 0.7 18.5 S248 U 162 U 970814 327.8 439 5.9 0.7 0.9 19.6

River R120 F 258 1 960709 457.3 310 5.3 0.1 0.3 7.9 S384 F 275 2 961105 458 242 3.9 0.1 0.3 5.5 S375 F 257 4 961105 455.3 270 2.7 0.0 0.4 6.2 R133 F 268 4 961211 456.1 185 2.5 0.6 0.6 8.1 S339 M 276 8 961105 454.7 209 1.1 2.8 0.6 10.1 S456 U 143 U 961105 458 273 0.2 0.0 0.1 0.9

1 S–sonic, R–radio 2 F–female, M–male, U–unknown 3 Stages: 1–previtellogenic 2–early vitellogenic 3–late vitellogenic 4–ripe 5–spent 6–previtellogenic w/ attritic oocytes 7–nonreproductive 8–reproductive U–unknown

Hells Canyon Complex Page 29 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Table 6. Summary of movement by telemetered white sturgeon in the Oxbow−Hells Canyon reach of the Snake River.

From Initial Capture Initial Total Capture Days MaxDistance MaxDistance Mean Distance Tag Date Location at Downstream Upstream Movement Traveled Number1 Sex2 TL (cm) Stage3 Tagged (RM) Large (river miles) (river miles) (river miles) (river miles) Oxbow–Hells Canyon Reservoir S2443 F 250 3 980323 263.8 479 11.5 7.6 4.1 73.8 S2525 F 236 4 980406 269.9 417 15.9 0.0 2.8 45.3 S447 U 139 U 980323 263.4 479 11.1 5.5 4.6 92.3

1 S–sonic, R–radio 2 F–female, M–male, U–unknown 3 Stages: 1–previtellogenic 2–early vitellogenic 3–late vitellogenic 4–ripe 5–spent 6–previtellogenic w/ attritic oocytes 7–nonreproductive 8–reproductive U–unknown

Table 7. Mortality and survival estimates for white sturgeon sampled in the Snake River between Bliss and Lower Granite dams.

Annual Annual Reach Survey Year Ages Survival (S) Mortality (A) Reference

Bliss–C.J. Strike 2000 7–21 0.87 0.13 IPC, unpubl. data C.J. Strike–Swan Falls 1994–96 12–21 0.91 0.09 Lepla and Chandler 1997 Hells Canyon–Salmon River 1997–00 6–13 0.87 0.13 Lepla et al. 2001 Hells Canyon–Lower Granite 1997–00 6–12 0.96 0.04 Tuell and Everett 2001

Page 30 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Table 8. Summary of movement by telemetered white sturgeon in the Hells Canyon−Salmon River reach of the Snake River.

From Initial Capture Initial Total Capture Days MaxDistance MaxDistance Mean Distance Tag TL Date Location at Downstream Upstream Movement Traveled Number1 Sex2 (cm) Stage3 Tagged (RM) Large (river miles) (river miles) (river miles) (river miles) Hells Canyon–Salmon Reservoir S375 F 174 1 7/27/99 196.6 329 0.1 15.7 2.7 16.2 S662 F 212 1 00/04/11 — 112 0 0.5 0.1 0.5 S2543 F 272 1 4/17/00 201.1 106 0.4 0.7 0.3 1.5 S365 F 200 1 9/19/97 190.4 579 1.5 1.1 0.2 4.8 S456 F 237 2 4/13/99 218.7 387 16.9 1.2 2.4 40

S455/4 F 206 2 (4) 9/04/98 228.8 255 0.0 (0.0) 0.1 (2.0) 0.04 (0.6) 0.5 (4.2) (S248) (F) (205) (4/11/00) (228.8) (113) S375 F 174 1 7/27/99 196.6 329 0.1 15.7 2.7 16.2 S249 F 240 4 3/22/99 224.4 193 60.7 0 5.1 96.3 S294 F 225 4 4/04/00 211.7 120 12.7 11.4 5.3 37.2 S276 F 220 5 7/27/99 193.9 253 0.0 1.3 0.3 2.3 S2255 M 265 7 8/10/99 199.7 353 3.2 0.0 0.4 6.6 S356 M 192 7 4/12/00 228.1 572 1.6 1.0 0.2 4.8

S2236/4 M 200 7 (7) 8/07/98 199.0 648 0 29.9 3.3 89.6 (S254) (M) (217) (00/04/12) (226.8) S34 M 200 7 5/09/00 236.3 85 0.0 1.6 0.5 2.5 S510 M 182 7 8/07/98 197.5 679 3.7 0.6 0.4 9.9 S2353 M 201 7 7/11/98 210.5 365 1.1 0.3 0.3 6.0 S2336 M 193 8 8/10/99 203.3 332 0.2 0.1 0.03 0.3 S366 M 202 8 7/08/98 207.9 323 1.0 0.0 0.1 1.4 S933 U 264 U 4/20/99 200.1 340 3.6 0.1 0.5 7.5 S239 U 151 U 10/16/97 238.1 594 0.3 7.4 0.5 16.1 S465 U 152 U 10/01/97 199.7 910 0.2 26 2.2 26.8 S377 U 138 U 7/08/98 207.9 367 2.8 0 0.5 9.5

1 S–sonic, R–radio 2 F–female, M–male, U–unknown 3 Stages: 1–previtellogenic 2–early vitellogenic 3–late vitellogenic 4–ripe 5–spent 6–previtellogenic w/ attritic oocytes 7–nonreproductive 8–reproductive U–unknown 4 Fish recaptured and retagged

Hells Canyon Complex Page 31 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Table 9. Mean relative weights based on fork length measurements for white sturgeon populations in the Snake River between Bliss and Lower Granite dams.

Mean Relative Mean Relative Mean Relative Weight Weight Weight River Segment Year All Fish (N) Reservoir (N) River (N)

Bliss–C.J. Strike 1991–93 99% (534) 101% (455) 91% (79)

Swan Falls–Brownlee 1996–97 86% (37) 82% (10) 87% (27)

Oxbow–Hells Canyon 1998 93% (2) 93% (2) —

Hells Canyon– 1997–00 88% (568) — 88% (568) Salmon River

Hells Canyon–Lower 1997–00 88% (1247) 95% (269) 87% (978) Granite1

Hells Canyon–Lewiston2 1982–84 89% (394) — 89% (394)

Hells Canyon–Lower 1972–75 90% (600) — 90% (600) Granite3

1 Data combined from Idaho Power Company and Nez Perce Tribe sturgeon surveys between Lower Granite and Hells Canyon dams. 2 Relative weights estimated from Lukens (1985) catch data provided to Idaho Power by Idaho Department of Fish and Game. 3 Relative weights estimated Coon et al. (1977) catch data provided to Idaho Power by Idaho Department of Fish and Game.

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Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

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Page 34 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

0.6 Setline Y = -2.86 + (-0.378* TL) + (0.028 * TL) (ln TL) + (1.28 * TL)/(ln TL) 0.5 r 2 = 0.86

a) 0.4

0.3

0.2

0.1

0 0 100 200 300 400

0.35

Recap Rate Recap Gill Net Y = -0.041 + (-0.004* TL) + (-0.0000219 * TL23 ) + (0.0000000286 * TL ) 0.3 r 2 = 0.69

0.25 b) 0.2

0.15

0.1

0.05

0 0 100 200 300 400 Total Length (cm)

Figure 2. Gear selectivity rates for white sturgeon sampled with setline and gill net gears in the Snake River.

Hells Canyon Complex Page 35 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

120 Swan Falls Brownlee Oxbow Hells Canyon Lower Granite

100

80

Salmon River 60 free-flowing reservoir

Number of Fish 40

20

0 440 420 400 380 360 340 320 300 280 260 240 220 200 180 160 140 120 River Mile

Figure 3. Distribution of Snake River white sturgeon between Swan Falls and Lower Granite dams. Data below Hells Canyon Dam include sturgeon sampled by the Nez Perce Tribe between the Salmon River and Lower Granite Dam.

Page 36 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

0.12 Swan Falls Brownlee Oxbow Hells Canyon Salmon River

0.10 a) n = 32 n = 0 n = 4 n = 841

0.08

0.06 free-flowing reservoir

0.04 Catch (fish/hr)

0.02

0.00 460 450 440 430 420 410 400 390 380 370 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 210 200 190

Swan Falls Brownlee Oxbow Hells Canyon Salmon River 2000 b) n = 2,913 n = 16,752 n = 2,690 n = 27,658

1500

free-flowing reservoir 1000 Hours of Effort

500

0 460 450 440 430 420 410 400 390 380 370 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 210 200 190

River Mile

Figure 4. Setline catch rates and hours of effort expended during sampling of white sturgeon in the Snake River from Swan Falls Dam to the mouth of the Salmon River.

Hells Canyon Complex Page 37 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

0.5 Swan Falls Brownlee Oxbow Hells Canyon Salmon River

a) 0.4 n = 12

0.3

free-flowing reservoir

0.2 Catch (fish/hr)

0.1

0.0 460 450 440 430 420 410 400 390 380 370 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 210 200 190

Swan Falls Brownlee Oxbow Hells Canyon Salmon River

30 b)

n = 268 n = 32 n = 39

20

free-flowing reservoir

Hours of Effort 10

0 460 450 440 430 420 410 400 390 380 370 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 210 200 190

River Mile

Figure 5. Gill net catch rates and hours of effort expended during sampling of white sturgeon in the Snake River downstream of Swan Falls Dam to the mouth of the Salmon River.

Page 38 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

40 Swan Falls - Brownlee a) IPC 1996-97 30 n= 30

92 cm 183 cm 20 4% 26% 70%

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 40 Oxbow - Hells Canyon b) IPC 1998 30 n= 4

20 18%92 cm 15% 183 cm 67%

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 40 c) Hells Canyon - Salmon River IPC 1997-00 30 Percent Catch n= 612

20 92 cm 183 cm 56% 25% 19%

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 40 Hells Canyon - Lower Granite d) IPC - NPT Data Combined 1997-00 30 n= 1005

92 cm 183 cm 20 53% 29% 18%

10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Total length (cm)

Figure 6. Length-frequency distributions (adjusted for gear selectivity) of white sturgeon sampled with setlines in the Snake River reaches from Swan Falls to Lower Granite dams.

Hells Canyon Complex Page 39 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

40 Swan Falls - Brownlee IPC 1996- 97 n = 12 30

92 cm 183 cm 20 0% 79% 21%

Percent Catch Percent 10

0 0 20 40 60 80 100 120 140 160 180 200 220 240 Total length (cm)

Figure 7. Length-frequency distribution (adjusted for gear selectivity) of white sturgeon sampled by gill nets in the Snake River between Swan Falls and Brownlee dams.

Page 40 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

300

250

a) 200 Swan Falls-Walters Ferry VBG Linfinity: 290, K:0.046, To: -1.117 150 Hells Canyon-Lower Granitea) VBG Linfinity: 296, K: 0.047, To: -0.659

100 Hells Canyon-Lower Granite 1997-00 n=247 Swan Falls-Walters Ferry 1996-97 50 n=21 Oxbow-Hells Canyon 1998 n=3 0 0 5 10 15 20 25 30 35 40 45 50 55 60

300

250 b)

200 Mean Total Length (cm) Length Total Mean

150

Hells Canyon-Lower Granite VBG 100 Hells Canyon-Lower Granite 1997-00 Coon et al. (1977) Lukens (1984) 50

0 0 5 10 15 20 25 30 35 40 45 50 55 60 Age (years)

Figure 8. Mean length-at-age and von Bertalanffy growth (VBG) lines for white sturgeon in the Snake River between Swan Falls and Lower Granite dams in graphs a) and b). VBG function for Hells Canyon−Lower Granite sturgeon population was estimated by Tuell and Everett (2001) using combined age data from IPC and Nez Perce Tribe 1997–2000 sturgeon surveys.

Hells Canyon Complex Page 41 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

100 Hells Canyon Dam - Salmon River 1997-00 3.274 a) Wt = 1.267E-06 TL 80 Hells Canyon Dam - Lower Granite 1997-00 3.094 Wt = 3.42E-06 TL

60 Swan Falls - Brownlee 1996-97 3.160 Wt = 2.264E-06 TL

40

20

0 0 20 40 60 80 100 120 140 160 180 200 220 240

100

Weight (kg) Weight Hells Canyon Dam - Lower Granite b) 80 1972-75 (Coon et al. 1977) 1982-84 (Lukens 1985) 1997-00 60

40

20

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Total Length (cm)

Figure 9. Length-weight relationships for white sturgeon sampled in the Snake River downstream of Swan Falls and Hells Canyon dams.

Page 42 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

160 150 Swan Falls - Brownlee a) Brownlee Reservoir Mean = 82% 140 1996-97 130 Swan Falls - Walters Ferry Mean = 87% 120 110 Standard 100 90 80 Population Mean =86% 70 60 50 40 30 50 100 150 200 250 300 160 150 Oxbow - Hells Canyon Hells Canyon Reservoir 140 1998 b) Mean = 93% 130 120 110 Standard 100 90 Population 80 Mean=93% 70 60

Relative Weight (%) Weight Relative 50 40 30 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 160 Hells Canyon - Lower Granite Lower Granite Reservoir (Nez Perce Tribe) 150 1997-00 c) Mean=95% 140 Hells Canyon Dam - Lower Granite Reservoir 130 (Idaho Power/ Nez Perce Tribe) Mean = 87% 120 110 Standard 100 90 80 Population Mean=88% 70 60 50 40 30 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

Fork Length (cm)

Figure 10. Relative weights of white sturgeon sampled in the Snake River between Swan Falls and Lower Granite dams. Length and weight data below Hells Canyon Dam were combined with sturgeon data collected by the Nez Perce Tribe.

Hells Canyon Complex Page 43 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Max Distance from Capture (%) Mean Movement (river miles) 30 Swan Falls - Brownlee 0-5 rm: 46 Reservoir 1.3 5-10 rm: 27 River 0.4 n= 11 sturgeon >10 rm: 27 20

10

0

-10

-20 a)

-30

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920

Max Distance from Capture (%) Mean Movement (river miles) 30 Oxbow - Hells Canyon 0-5 rm: - Reservoir 4.0 5-10 rm: - River - n = 3 sturgeon >10 rm: 100 20

10

0

-10

-20 b)

-30

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920

Maximum Distance Traveled from Initial Capture (river miles) Initial (river from Capture Distance Traveled Maximum 30 Hells Canyon - Salmon River n = 21 sturgeon 20

10

0

-10

Max Distance from Capture (%) Mean Movement (river miles) -20 c) 0-5 rm: 68 Reservoir - 5-10 rm: 5 River 1.2 -30 >10 rm: 27 -60 0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880 920 Days at Large

Figure 11. Range of movement activity for telemetered white sturgeon in Snake River reaches between Swan Falls Dam and the mouth of the Salmon River.

Page 44 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

350

340

330 320 a) 310 S555: Female - Early Vitellogenic 300 Upstream end of Reservoir 290 Brownlee Dam

9/1/96 11/1/96 1/1/97 3/1/97 5/1/97 7/1/97 9/1/97 11/1/97 1/1/98 3/1/98 5/1/98 7/1/98 9/1/98 11/1/98 350

340

330

320 b) 310 S285: Female Early vitellogenic 300 Upstream end of Reservoir 290 Brownlee Dam

9/1/96 11/1/96 1/1/97 3/1/97 5/1/97 7/1/97 9/1/97 11/1/97 1/1/98 3/1/98 5/1/98 7/1/98 9/1/98 11/1/98 350

340

330

320

310 S357: Female Early Vitellogenic c)

River Mile Upstream end of Reservoir 300

290 Brownlee Dam

9/1/96 11/1/96 1/1/97 3/1/97 5/1/97 7/1/97 9/1/97 11/1/97 1/1/98 3/1/98 5/1/98 7/1/98 9/1/98 11/1/98 350

340

330

320

310 d)

300 S3434: Male Upstream end of Reservoir 290 Brownlee Dam

9/1/96 11/1/96 1/1/97 3/1/97 5/1/97 7/1/97 9/1/97 11/1/97 1/1/98 3/1/98 5/1/98 7/1/98 9/1/98 11/1/98 350

340

330 320 e) 310 S248: Sex Unknown 300 Upstream end of Reservoir 290 Brownlee Dam

9/1/96 11/1/96 1/1/97 3/1/97 5/1/97 7/1/97 9/1/97 11/1/97 1/1/98 3/1/98 5/1/98 7/1/98 9/1/98 11/1/98 Date

Figure 12. Locations of telemetered white sturgeon (S555, S285, S357, S3434) in Brownlee Reservoir.

Hells Canyon Complex Page 45 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

35 a) 30 Swan Falls - Brownlee

25

20

15

10

5

0 Reservoir River Reservoir River Reservoir River Reservoir River Spring Summer Fall W inter

35

30 b) Oxbow - Hells Canyon (reservoir) 25

20

15

10

5

0 Spring Summer Fall Winter Range mile) of(river Movement

35 Hells Canyon - Salmon River 30 c) (river) 25

20

15

10

5

0 Spring Summer Fall Winter Season

Figure 13. Seasonal range of activity (between tracking events) for telemetered white sturgeon in Snake River reaches between Swan Falls Dam and the mouth of the Salmon River. Small boxes indicate median values, large boxes the 25th and 75th percentiles, and vertical lines the minimum and maximum values.

Page 46 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

80 70 a) 10/0 60 n = 56 50 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 80 70 b) 12/0 60 n = 178 50 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 80 70 c) 14/0 60 n = 169 50

Number ofFish 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 80 70 d) 16/0 60 n = 162 50 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280

Total Length (cm)

Figure 14. Length-frequency distribution of white sturgeon collected by setline hook sizes (10/0, 12/0, 14/0, 16/0) in the Snake River between Swan Falls Dam and the mouth of the Salmon River below Hells Canyon Dam.

Hells Canyon Complex Page 47 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

25 Hells Canyon - Salmon River a) IPC 1997-00 20 n = 74

15 92 cm 183 cm

46% 28% 27% 10

5

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280

25 Hells Canyon - Lower Granite b) IPC - NPT Data Combined 1997-00

Percent Catch Percent 20 n = 144

15 92 cm 183 cm 57% 26% 17% 10

5

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Total Length (cm)

Figure 15. Length frequencies of white sturgeon sampled by angling gear in the Snake River below Hells Canyon Dam during Idaho Power Company and Nez Perce Tribe sturgeon surveys.

Page 48 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

30

Swan Falls Dam 1991-2000

C 25 Snake River at Weiser, ID O 1996-2000

20

15

10

5 Mean Daily Temperature Daily Mean

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360

Julian Date

Figure 16. Mean daily water temperatures in the Snake River at Swan Falls Dam (1991–2000) and Weiser, Idaho (1996–2000).

Hells Canyon Complex Page 49 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

80 70 a) IDFG 60 1986-87 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 80 70 IPC b) 60 1996-97

Percent Catch Setline 50 n=30 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm Size Group

Figure 17. Size composition of white sturgeon sampled between Swan Falls and Brownlee dams. Idaho Department of Fish and Game data for 1986–87 were obtained from IDFG's White Sturgeon Management Plans (1992 draft).

Page 50 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

100 90 a) Coon et al. 1977 80 1972-75 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 b) Lukens 1985 80 1982-84 70 60 50 40 30 Percent Catch 20 10 0 < 92 cm 92 - 183 cm > 183 cm 100 90 c) IPC/NPT 80 1997-00 70 60 50 40 30 20 10 0 < 92 cm 92 - 183 cm > 183 cm Size Group

Figure 18. Size composition of white sturgeon sampled in the Snake River between Hells Canyon and Lower Granite dams.

Hells Canyon Complex Page 51 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

60 Bliss - CJ Strike Reach n=225 50

40

30

20

10

0

-10

-20

-30

-40

-50 Distance Traveled Between Captures (river miles) -60

0123456789

Years at Large

Figure 19. Distance traveled between capture periods by white sturgeon in the Snake River between Bliss and C.J. Strike dams.

Page 52 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 1. Locations of telemetered white sturgeon (R120, S248, S456) in the Snake River between Swan Falls and Brownlee dams.

460 450 Swan Falls Dam 440 R120 430 Female - Previtellogenic 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 460 450 Swan Falls Dam S248 440 Sex Unknown 430 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 River Mile River 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 460 450 Swan Falls Dam S456 440 Sex Unknown 430 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 Date

Hells Canyon Complex Page 53 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 2. Locations of telemetered white sturgeon (S357, S285) in the Snake River between Swan Falls and Brownlee dams.

460 Swan Falls Dam 450 S357 440 Female - Early Vitellogenic 430 420 410 400 390 380 370 360 350 Upstream end of Reservoir 340 330 320 310 300 290 Brownlee Dam

6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 460 450 Swan Falls Dam S285

River Mile River 440 Female - Early Vitellogenic 430 420 410 400 390 380 370 360 350 Upstream end of Reservoir 340 330 320 310 300 290 Brownlee Dam

6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98

Date

Page 54 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 3. Locations of telemetered white sturgeon (S555, S384) in the Snake River between Swan Falls and Brownlee dams.

460 Swan Falls Dam 450 S555 440 Female - Early Vitellogenic 430 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98

460 450 Swan Falls Dam Fish S384

River Mile River 440 Female - Early Vitellogenic 430 420 410 400 390 380 370 360

350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98

Date

Hells Canyon Complex Page 55 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 4. Locations of telemetered white sturgeon (S375, R133) in the Snake River between Swan Falls and Brownlee dams.

460 Swan Falls Dam 450 S375 440 Female - Ripe 430 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 460 450 Swan Falls Dam R133 440 River Mile River Female - Ripe 430 420 410 400 390 380 370 360

350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98

Date

Page 56 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 5. Locations of telemetered white sturgeon (S339, S3434) in the Snake River between Swan Falls and Brownlee dams.

460 450 Swan Falls Dam Fish S339 440 Male - Reproductive 430 420 410 400 390 380 370 360 350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98 460

River Mile River 450 Swan Falls Dam Fish S3434 440 Male - Reproductive 430 420 410 400 390 380 370 360

350 Upstream end of Brownlee Reservoir 340 330 320 310 300 290 Brownlee Dam 280 6/1/96 10/1/96 2/1/97 6/1/97 10/1/97 2/1/98 6/1/98 10/1/98

Date

Hells Canyon Complex Page 57 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 6. Locations of telemetered white sturgeon (S2443, S447, S2525) in the Snake River between Oxbow and Hells Canyon dams.

275 Oxbow Spillway

270 Oxbow Dam

265

260

255

S2443 250 Hells Canyon Dam Female Late Vitellogenic

3/1/1998 5/1/1998 7/1/1998 9/1/1998 11/1/1998 1/1/1999 3/1/1999 5/1/1999 7/1/1999

275 Oxbow Spillway

270 Oxbow Dam

265

260

River Mile River 255

S447 250 Sex Unknown Hells Canyon Dam

3/1/1998 5/1/1998 7/1/1998 9/1/1998 11/1/1998 1/1/1999 3/1/1999 5/1/1999 7/1/1999

275 Oxbow Spillway

270 Oxbow Dam

265

260

255

S2525 250 Female - Ripe Hells Canyon Dam

3/1/1998 5/1/1998 7/1/1998 9/1/1998 11/1/1998 1/1/1999 3/1/1999 5/1/1999 7/1/1999

Date

Page 58 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 7. Locations of telemetered white sturgeon (S375, S622, S2543) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam S375 225 Female - Previtellogenic 210

195 Salmon River 180 165 150 Upstream of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 240 Hells Canyon Dam S622 225 Female - Previtellogenic 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S2543

River Mile River 225 Female - Previtellogenic 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

Date

Hells Canyon Complex Page 59 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 8. Locations of telemetered white sturgeon (S365, S456, S249) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam S456 225 Female - Early Vitellogenic 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00

240 Hells Canyon Dam S456 225 Female - Early Vitellogenic 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105

River Mile River Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S249 225 Female - Ripe 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

Date

Page 60 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 9. Locations of telemetered white sturgeon (S455/S248, S294, S276) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam 225 210

195 Salmon River Early Vitellogenic 180 Ripe 165 150 Upstream end of Reservoir 135 S455/S248 120 Female - Early Vitellogenic/Ripe Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S294 225 Female - Ripe 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S276 225 Female - Spent 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

Date

Hells Canyon Complex Page 61 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 10. Locations of telemetered white sturgeon (S34, S2236/S254, S356, S2353) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam S34 225 Male - Non reproductive 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 240 Hells Canyon Dam 225 210

195 Salmon River 180 S2236/254 165 Male - Non reproductive Upstream end of Reservoir 150 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S356

River Mile River 225 Male - Non reproductive 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S2353 225 Male - Non reproductive 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Date

Page 62 Hells Canyon Complex Idaho Power Company Chapter 1: Status of Snake River White Sturgeon

Appendix 11. Locations of telemetered white sturgeon (S510, S2255, S366, S2336) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam S510 225 Male - Non reproductive 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 240 Hells Canyon Dam S2255 225 Male - Non reproductive 210

195 Salmon River 180 165 Upstream end of Reservoir 150 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S366 Male - Reproductive River Mile River 225 210

195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam S2336 Male - Reproductive 225 210

195 Salmon River 180 165 Upstream end of Reservoir 150 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Date

Hells Canyon Complex Page 63 Status and Habitat Use of Snake River White Sturgeon Idaho Power Company

Appendix 12. Locations of telemetered white sturgeon (S377, S465, S239, S933) in the Snake River between Hells Canyon and Lower Granite dams.

240 Hells Canyon Dam S377 225 Sex Unknown 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 240 S465 Hells Canyon Dam 225 Sex Unknown 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135

120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01

240 Hells Canyon Dam 225 S239 210 Sex Unknown 195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00

240 Hells Canyon Dam S933 225 Sex Unknown 210 195 Salmon River 180 165 150 Upstream end of Reservoir 135 120 Lower Granite Dam 105 Jan-97 Jul-97 Jan-98 Jul-98 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Date

Page 64 Hells Canyon Complex