2010 RC-C Backpack Fish Population Final Report-No App B-C March 2011

ROCK CREEK-CRESTA PROJECT (FERC No. 1962) BACKPACK ELECTROFISHING SURVEYS OF SHALLOW-WATER HABITATS – OCTOBER 2010 Prepared for:

Technical and Scientific Support Pacific Gas and Electric Company 3401 Crow Canyon Road San Ramon, California 94583

Final Report

Prepared by:

Tim Salamunovich Thomas R. Payne & Associates P.O. Box 4678 890 L Street Arcata, California 95521 (707) 822-8478

March, 2011

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Data Report – Notice to Readers

This monitoring data report is part of Pacific Gas and Electric Company’s ongoing effort to meet the study requirements of Condition 7 of the Rock Creek – Cresta Project License (FERC No. 1962). This report is part of a 15-year monitoring effort conducted in consultation with the Ecological Resources Committee (ERC) organized under the Rock Creek – Cresta Relicensing Settlement Agreement. This report has been submitted to the ERC for review and comment. This data report is part of an on-going long-term study effort, it is not the intent, after this first year of study of the second 5-year study period, to present conclusions or recommendations on the effect of changes in release flows during this second flow evaluation period. Recommendations within this 2010 report relate to changes in future backpack electrofishing efforts, data analysis, and any conclusions focus on comparisons with the 2002, 2004-2006, California Department of Fish and Game’s 1982-1986 backpack efforts and to the fishery criteria identified in the Rock Creek-Cresta Operating License and Settlement Agreement.

Table of Contents Table of Contents ...... i List of Figures ...... ii List of Tables ...... iii List of Appendices ...... iv Introduction ...... 1 Study Area/Study Sites ...... 5 Methods ...... 11 Physical Site Data Collection ...... 11 Electrofishing ...... 12 Results ...... 15 Physical Site Data Collection ...... 17 Bear Ranch Creek Site ...... 19 Grizzly Creek Site ...... 19 Granite Creek Site ...... 19 Rodgers Flat Site ...... 20 Electrofishing ...... 21 Discussion ...... 42 Conclusions ...... 58 Criteria A. Wild rainbow trout population with 4 age classes ...... 60 Criteria D. Adult rainbow trout available for catch > 17 inches ...... 60 Criteria E. Harvestable component of 595 lbs/mile wild trout ...... 60 Criteria F. Wild trout biomass 62 lbs/acre (catch) ...... 62 Trout condition factor ...... 63 Functional ecosystem to all naturally occurring species ...... 63 Recommendations ...... 64 Literature Cited ...... 64

List of Figures 1. Mean stream flows for summer through early fall period (1 July – 15 October) in the Rock Creek and Cresta reaches of the North Fork Feather River since 2000 ...... 4 2. Map of Pacific Gas and Electric Company’s North Fork Feather River hydroelectric facilities (powerhouses shown by red circles) including the Rock Creek-Cresta Project (FERC No. 1962) ...... 6 3. Location of the four October 2010 shallow-water electrofishing sites in the Rock Creek-Cresta Project area of the North Fork Feather River ...... 7 4. Stream flow records for the Rock Creek and Cresta study reaches during the October 2010 backpack electrofishing survey ...... 16 5. Length-frequency data for rainbow trout captured during the October 2010 Rock Creek- Cresta electrofishing survey ...... 23 6. Condition factor-frequency data for rainbow trout captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 27 7. Length-frequency data for brown trout and hardhead captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 28 8. Length-frequency data for Sacramento pikeminnow captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 29 9. Length-frequency data for Sacramento sucker captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 31 10. Length-frequency data for smallmouth bass captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 32 11. Length-frequency data for riffle sculpin captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 33 12. Length-frequency data for prickly sculpin captured during the October 2010 Rock Creek-Cresta electrofishing survey ...... 35 13. Relative species abundance presented as a percentage of the total population estimate at each of the Rock Creek-Cresta study sites during the October 2010 shallow-water electrofishing survey ...... 37 14. Relative species biomass presented as a percentage of the total biomass estimates at each of the Rock Creek-Cresta study sites during the October 2010 shallow-water electrofishing survey ...... 41 15. Length-frequency data for rainbow trout captured during six separate late-fall electrofishing surveys in the Cresta Reach of the NFFR ...... 53 16. Length-frequency data for rainbow trout captured during six separate late-fall electrofishing surveys in the Rock Creek Reach of the NFFR ...... 54 17. Mean daily stream flow records for the Cresta and Rock Creek study reaches for the 2007-2010 water years ...... 59

List of Tables 1. Electrofishing fish population monitoring completed and scheduled as specified in the Rock Creek-Cresta Relicensing Settlement Agreement (SA) ...... 2 2. Levels of catchable-sized rainbow trout stocked in Belden area of North Fork Feather River for past ten years ...... 8 3. Number, lengths in feet, and percentage of total distance for the habitat types identified during habitat mapping of the main channel areas of the Cresta and Rock Creek reaches, 26-27 August 2010 ...... 9 4. Name, Project reach location, and predominant habitat type for the four Rock Creek-Cresta shallow-water electrofishing sites sampled in October 2010 ...... 10 5. Location of upstream boundary, date surveyed, and summary of habitat and water quality measurements for the four Rock Creek-Cresta shallow-water electrofishing sites sampled in October 2010 ...... 18 6. Fish species collected at the four Rock Creek-Cresta Project shallow-water electrofishing sample sites, October 2010 ...... 21 7. Age-length data for rainbow trout captured at the four Rock Creek-Cresta electrofishing sites sampled in October 2002 (ECORP 2003) and TRPA composite age-length intervals ...... 24 8. Estimated rainbow trout age class distributions at the four Rock Creek-Cresta sites surveyed in October 2010 using the TRPA composite age-length intervals derived from the 2002 age-length analysis from ECORP (2003) ...... 24 9. Multiple pass removal-depletion patterns and electrofishing statistics for fish species captured at the four shallow-water Rock Creek-Cresta sites sampled using backpack electrofishers in October 2010 ...... 36 10. Mean weights and biomass estimates (± 95% confidence intervals) by species based upon mean weights of captured fish, multiple pass removal-depletion population estimates, and the physical dimensions of the four shallow-water Rock Creek-Cresta sites sampled using backpack electrofishers in October 2010 ...... 39 11. Population estimate and mean weight summary for fish species sampled by electrofishing at five Rock Creek-Cresta shallow-water sites sampled since 1986 ...... 46 12. Estimated rainbow trout age class distributions at the five Rock Creek-Cresta sites surveyed in 2002 through 2010, based upon the TRPA composite age-length intervals derived from the 2002 age-length analysis from ECORP (2003) ...... 47 13. Standardized abundance estimates (number per mile) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986 ...... 48 14. Standardized abundance estimates (number per acre) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986 ...... 49

List of Tables (continued) 15. Standardized biomass estimates (pounds per mile) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986 ...... 50 16. Standardized biomass estimates (pounds per acre) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986 ...... 51 17. Biomass estimate for wild rainbow trout ≥ 8 inches in length for each of the habitats in the Cresta and Rock Creek reaches of the Project area for several years based on the annual snorkel count abundance estimates and annual shallow-water electrofishing length-weight relationships for that particular year ...... 62

List of Appendices A - Rock Creek-Cresta Relicensing Settlement Agreement Minimum Flow Schedules B - October 2010 Rock Creek-Cresta Shallow-water Electrofishing Site Habitat Characteristic Data Sheets C - October 2010 Rock Creek-Cresta Shallow-water Electrofishing Data Sheets D - MicroFish 3.0 and Program CAPTURE Output for the October 2010 Rock Creek- Cresta Shallow-water Electrofishing Data

Rock Creek-Cresta Project (FERC No. 1962) Backpack Electrofishing Survey of Shallow-water Habitats – October 2010

Introduction

In September 2000, Pacific Gas and Electric Company (PG&E) in concert with state and federal resource agencies, and with numerous other recreational and environmental groups signed the Rock Creek-Cresta Relicensing Settlement Agreement (SA). The SA attempts to strike a balance between continued hydropower generation from the Rock Creek-Cresta Hydroelectric Project (Federal Energy Regulatory Commission [FERC] Project No. 1962) (“Project”) and ecological and recreational restoration of the North Fork Feather River (NFFR).

The SA specified a 15-year schedule of changes to the Project base flows (see Appendix A) with an objective of providing “an excellent trout fishery and functioning ecosystem to all naturally occurring species”. The specific fishery performance criteria listed in the SA in determining this includes: A. Wild rainbow trout population with four age classes. B. Fish catch 80% wild trout / 20% non-game fish. C. Average wild trout caught >9.7 inches fork length. D. Adult rainbow trout available for catch >17 inches. E. Harvestable component of 595 lbs / mile wild trout F. Wild trout biomass 62 lbs / acre (catch). G. Angler catch rates of one fish per angling hour including catch and release.

In order to evaluate progress toward meeting these criteria over a range of three, 5-year base flow adjustments during the first 15 years of its operating license, PG&E is conducting periodic fish population monitoring (backpack electrofishing and dive counts) and angler creel surveys in the Rock Creek and Cresta reaches of the North Fork Feather River during the last three years of each 5-year period (as may be modified in response to water-year type, see page B-12 in Appendix B of SA). Not all criteria will be evaluated by each study effort, specifically, criteria A, D, E, and F will primarily be evaluated by the backpack electrofishing study with support from the dive counts study and criteria B, C and G will be

primarily evaluated by the angler creel survey study. Due to some data needs for criteria evaluation, data from multiple study efforts in some cases have been combined to evaluate whether a specific criteria has been met or not. Where this has occurred, the other study has been clearly identified.

The SA specifies that backpack electrofishing will be conducted in riffle and glide habitats fashioned after similar studies conducted during the 1980’s by the California Department of Fish and Game (CDFG 1988). The SA stipulates that the fish population monitoring should be conducted during the late summer/fall periods at specified annual intervals (Table 1). A first year effort to provide a baseline measure of fish populations prior to the initial base flow adjustment was completed in 2002 (ECORP 2003).

Table 1. Electrofishing fish population monitoring completed and scheduled as specified in the Rock Creek-Cresta Relicensing Settlement Agreement (SA). Year Calendar Year 1 SA base flow schedule year 2 Status

1 2002 First year of first 5-yr flow Completed & reported in ECORP period 2003

3-5 2004-2006 3rd through 5th years of first 5- 2004 survey completed & reported yr flow period in Salamunovich 2005 2005 survey completed & reported in Salamunovich 2006 2006 survey completed & reported in Salamunovich 2007b

9-11 2010-2012 3rd through 5th years of 2010 survey completed & second 5-yr flow period reported in this report

15-17 2015-2017 3rd through 5th years of third Future studies 5-yr flow period

1 Past and anticipated schedule (as may be affect by water-year designation, see Appendix B of SA). 2 The 5-year base flow periods specified in Section II (River Flow Management) of the Rock Creek-Cresta Relicensing Settlement Agreement (see Appendix A of this report).

Thomas R. Payne and Associates (TRPA) was contracted to conduct the shallow-water habitat electrofishing survey for Year 9 of the SA base flow assessment period, which represents the first year of the second three-year fish population monitoring assessment period (2010-2012; Table 1). The goal of the survey is to characterize the fishery

population (e.g., species composition, abundance, biomass, length frequencies, etc.) from selected sample sites in several shallow-water areas of the Rock Creek and Cresta reaches that can be sampled repetitively using backpack electrofishing techniques. The long-term hypothesis being tested, as outlined in the SA, is that programmatic increases in the base flows from the Rock Creek-Cresta Project will result in a corresponding increase in the quantity and quality of the aquatic habitat, and a concomitant increase in the trout population of the North Fork Feather River. The results of the monitoring will also reflect population responses of fish species other than trout to the base flow changes.

This report provides the results from the first of three consecutive years of backpack electrofishing surveys following the most recent increase in Project base flows and was conducted in association with three other concurrent 3-year monitoring efforts (i.e., dive count surveys, angler surveys, and benthic macroinvertebrate surveys). Summer base flows since the last population assessment in the late fall of 2006 have been variable. The first two years of this period (2007 and 2008), were categorized as “critically dry” years and although the SA stipulated minimum summer-early fall base flows of 140 and 150 cfs that were below the minimum ‘normal water year’ levels of 180 cfs and 220 cfs for the Rock Creek and Cresta reaches, respectively, of the preceding 5-year test flow period, the actual average releases generally ranged between 200 to 250 cfs (Figure 1). The third year of this period (2009) was categorized as “dry”, and had SA minimum release requirements of 210 and 260 cfs for Rock Creek and Cresta, respectively, although actual releases exceeded these minimums as well as the minimum flow releases for “normal” water year types as well (2009 was considered a “grace” year to allow the fish population a chance to respond to higher flows of the second 5-year test flow period and no sampling was conducted.). Return to “normal” water conditions in 2010 resulted in average summer base flows in excess of the SA stipulated minimum releases of 260 cfs in the Rock Creek reach and 325 cfs in the Cresta reach by about 100 to 150 cfs in each reach.

550

500 Cresta Reach Rock Creek Reach 450

400

350 G 300 E H 250 A F

Discharge(cfs) 200 B C 150 D 100

0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year

Figure 1. Mean stream flows for summer through early fall period (1 July–15 October) in the Rock Creek and Cresta reaches of the North Fork Feather River since 2000. (Blue and red lines represent the water-year (WY) type Settlement Agreement base flow releases for the Rock Creek and Cresta reaches, respectively). [Flow data from USGS and PG&E]. A = 1st 5-yr period normal WY release Cresta Reach (220 cfs); B = 1st 5-yr period normal WY release Rock Creek Reach (180 cfs); C = 2nd 5-yr period critically dry WY release Rock Creek Reach (150 cfs); D = 2nd 5-yr period critically dry WY release Cresta Reach (140 cfs); E = 2nd 5- yr period dry WY release Cresta Reach (260 cfs); F = 2nd 5-yr period dry WY release Rock Creek Reach (210 cfs); G = 2nd 5-yr period normal WY release Cresta Reach (325 cfs); H = 2nd 5-yr period normal WY release Rock Creek Reach (260 cfs).

All of these long-term surveys are designed to help assess the responses of the aquatic community to the base flow changes over the 15-year period and to track the progress toward attaining the objective of providing “an excellent trout fishery and functioning ecosystem to all naturally occurring species” in the Project area.

Study Area/Study Sites

The Rock Creek-Cresta Hydroelectric Project is located on the NFFR in Butte and Plumas Counties. The Project is an integral part of PG&E’s NFFR hydropower system, where stored water, mainly from Lake Almanor, produces electricity through a series of nine powerhouses before entering Lake Oroville (Figure 2).

The Rock Creek–Cresta Project consists of the Rock Creek Dam and Powerhouse and the Cresta Dam and Powerhouse. Water (3,300 cfs maximum) is diverted from the Rock Creek Reservoir through the Rock Creek Powerhouse and is discharged into the Cresta Reservoir. The 8.5 mile-long section of the NFFR bypassed by this portion of the Project is referred to as the Rock Creek Reach (Figure 3). From Cresta Reservoir, flow (maximum of 3,800 cfs) is diverted through the Cresta Powerhouse and into the Poe Reservoir. The 4.9 mile-long section of the river between Cresta Dam and powerhouse is known as the Cresta Reach of the NFFR (Figure 3).

The Bucks Creek Project (FERC No. 619) discharges water from the Bucks and Grizzly Creek basins into the lower portion of the Rock Creek Reach about one mile upstream of the Rock Creek Powerhouse (Figure 3). Major tributaries to the NFFR in the Project area include Opapee, Milk Ranch, Chambers, Granite, Bucks, Rock, Grizzly, and Bear Ranch creeks.

The Rock Creek-Cresta Project reaches of the North Fork Feather River are considered to be within an ecological transition area between the rainbow trout zone and the pikeminnow-sucker-hardhead zone (Moyle 2002). Moyle et al. (1983) described fish populations in the Project area as a mixture of native and introduced species including, rainbow trout (Oncorhynchus mykiss), Sacramento sucker (Catostomus occidentalis), Sacramento pikeminnow (Ptychocheilus grandis), hardhead (Mylopharodon conocephalus), riffle sculpin (Cottus gulosus), smallmouth bass (Micropterus dolomieu), and brown trout (Salmo trutta). Prickly sculpin (Cottus asper) are known to occur in the

Figure 2. Map of Pacific Gas and Electric Company’s North Fork Feather River hydroelectric facilities (powerhouses shown by red circles) including the Rock Creek-Cresta Project (FERC No. 1962).

Figure 3. Location of the four October 2010 shallow-water electrofishing sites (red fish symbols) in the Rock Creek-Cresta Project area of the North Fork Feather River. Location of Project facilities shown by yellow squares, stream gage sites shown by white triangles.

Project area (ECORP 2003; Salamunovich 2004a). Other less common species such as Sacramento perch (Archoplites interruptus), common carp (Cyprinus carpio), and wakasagi (or pond smelt, Hypomesus nipponensis) may also be present on occasion, after periodically washing out of Lake Almanor (Moyle et al. 1983).

Supplementation of the Rock Creek-Cresta trout populations using hatchery strains has been conducted with little regularity and limited success. In 1966-67 and 1977, several plants of hatchery-reared rainbow and brown trout were made into the Project area following extensive chemical treatments aimed at reducing the non-game fish populations (Flint 1980; Moyle et al. 1983). Between 1981 and 1986, the California Department of Fish and Game (CDFG) conducted an experimental trout stocking program in the Rock Creek-Cresta reaches; however, the program was discontinued after limited success attributed to poor habitat and lack of availability of strains resistant to the protozoan parasite, Ceratomyxa shasta (CDFG 1988).

CDFG continues to regularly stock hatchery trout in the NFFR about three miles upstream of the Project area near Belden (Table 2). Despite the upstream hatchery supplementation, the Rock Creek and Cresta reaches are no longer stocked, and the flowing, non-reservoir areas are currently managed as a wild trout fishery under “catch and release” regulations.

Table 2. Levels of catchable-sized rainbow trout stocked in Belden area of North Fork

Feather River for past ten years. Data provided by CDFG. Year Number Pounds Average weight/fish (pounds) 2001 10,900 5,500 0.51 2002 12,150 6,650 0.55 2003 10,840 5,500 0.52 2004 11,545 6,250 0.56 2005 10,590 5,700 0.54 2006 11,820 6,300 0.54 2007 11,700 5,000 0.48 2008 12,010 5,300 0.46 2009 11,138 4,900 0.46 2010 10,300 5,000 0.51 Average 11,299 5,620 0.51

The NFFR in the Project reaches is a relatively high-gradient river contained in a steep- walled canyon. At the current normal water year summer base flows (325 cfs in the Cresta Reach and 260 cfs in the Rock Creek Reach), the river in the Project area is composed primarily of relatively long deeper-water habitats such as pools and runs that are separated by shorter shallow-water cascade and riffle habitats (Table 3).

Table 3. Number, lengths in feet (total/mean), and percentage of total distance for the habitat types identified during habitat mapping of the main channel areas of the Cresta and Rock Creek1 reaches, 26-27 August 2010. Habitat Type N Total length Mean length % Total Reach

Cresta Reach (Discharge = 477 cfs)

Cascade 5 340 68.0 1.3 Low gradient riffle 8 941 117.6 3.7 High gradient riffle 23 4,024 175.0 15.7 Run 45 9,340 207.6 36.5 Shallow pool 14 3,355 239.6 13.1 Deep pool (<10ft) 15 7,576 505.1 29.6

Rock Creek Reach1 (Discharge = 337 cfs)

Cascade 23 1,625 70.7 4.2 Low gradient riffle 24 4,067 169.5 10.4 High gradient riffle 24 4,862 202.6 12.5 Run 47 11,934 253.9 30.6 Pocket water 18 2,308 128.2 5.9 Shallow pool 14 3,943 281.3 10.1 Deep pool (<10ft) 27 10,222 378.6 26.2

1 lower mile of channel downstream of Bucks Project Powerhouse was not included in mapping.

Most of the gradient change occurs over the short stretches of cascade and riffle habitat. This predominance of deep-water habitats in the Project area limits the amount of wadeable, shallow-water habitats that can be sampled using backpack electrofishing equipment. The study’s goal to sample habitat distances 200-400 feet in length further constrains the availability of suitable sample sites in the Project area.

The Ecological Resource Committee (ERC) approved study plan specified that, at a minimum, the same four sites be sampled during the three 5-year monitoring periods. The intent of this site “loyalty” stipulation was to allow comparisons of current fish population levels to “recent” historical levels in the mid 1980’s (CDFG 1988). This prerequisite was complicated by the fact that high flows in February 1986 resulted in altered the stream channel (and fish habitat) conditions that were present during the CDFG multi-year studies (CDFG 1988). High flows in January 1997 resulted in additional changes to the NFFR channel geomorphology. One sample site included in the 2002, 2004, and 2005 surveys is no longer among the sample sites. After consultation with the ERC and PG&E, a substitute shallow-water site near the mouth of Granite Creek, that actually corresponds to the historical CDFG 1986-1988 site was added in 2005 (replacing the Indian Jim School Site in the Rock Creek Reach) and has been sampled in the surveys since that time (Salamunovich 2006, 2007b).

The four shallow-water sites sampled during 2010 represented a predominantly run/riffle or pocket water habitat from the Rock Creek and Cresta reaches (Table 4; Figure 3). The study sites were named for easily recognizable physical or geographic features in the vicinity and generally follow the conventions used in the first year baseline monitoring report (ECORP 2003).

Table 4. Name, Project reach location, and predominant habitat type for the four Rock Creek-Cresta shallow-water electrofishing sites sampled in October 2010. Site name Project Reach Predominant habitat Bear Ranch Creek Cresta Run Grizzly Creek Cresta Run/riffle Granite Creek Rock Creek Run/riffle Rodgers Flat Rock Creek Pocket water/Run

Methods

Physical Site Data Collection

The upper and lower boundaries of the four study sites were relocated the day prior to the 2010 sampling using photos and Global Positioning System (GPS) coordinates. Habitat dimensions, habitat characteristics, and water quality parameters were measured at all electrofishing sites at the time they were sampled. All habitat measurement and characterization data were recorded on standardized data forms.

The length of each site was measured to the nearest foot from the bottom boundary to the top boundary using a hip chain. Stream width to the nearest 0.1 foot was measured at a minimum of eleven locations along the sampling station using a surveyors tape. The average of these measurements was used to determine the mean width at each station, which was used in combination with reach length to estimate a total sample area. Depth measurements (to the nearest 0.05 foot) were made using a survey stadia rod at ¼, ½, and ¾ distance across each of the width cross-sections to estimate the average depth for the entire sample station. The maximum depth within each of the stations was also recorded using the deepest reading made within the particular survey unit. Stream gradient over the length of each site was measured using a hand-level and the stadia rod placed on the water surface at the top and bottom boundaries.

Habitat characteristics within each of the survey stations were also recorded at the time of sampling. The percentages of different habitat types (pool, run, riffle, or pocket water) comprising the station were visually estimated, along with the percentages of various substrate types (fines [<2 mm], sand [2-7 mm], gravel [8-75 mm], cobble [76-300 mm], boulder [>300 mm] and bedrock). The percent of the site available as fish cover was also estimated using the same categories reported in ECORP (2003), which included surface turbulence, instream object cover, undercut bank, and overhanging vegetation within 48” of the water surface. The surface area of suitable trout spawning gravels in the study site was also estimated.

Water temperature was recorded at the time the stations were sampled. Other water quality parameters were also measured, including pH, conductivity (μS/cm), specific conductivity (temperature standardized conductivity), salinity (ppt), and dissolved oxygen concentrations (mg/L), and percent saturation. The pH was measured using a Eutech/Oakton Instruments® handheld ecoTestr pH2 meter. Remaining water quality parameters were measured using recently-calibrated Yellow Spring Instruments® handheld meters (Models 30 and 550).

To aid in relocating stations during future efforts, the top and bottom boundaries along each bank were denoted used high-visibility surveyors flagging. The flagging was hung near the waters edge as well as further up the bank. In addition, orange plastic squares with flagging were attached to trees well up the bank at the top and bottom boundaries of each site. In addition, sites were photographed from multiple vantage points, and the latitude and longitude of the top and bottom boundaries were determined using a handheld GPS receiver.

Electrofishing

Estimation of the abundance and population characteristics of resident fish in the shallow water areas of the Rock Creek and Cresta reaches of the NFFR was conducted using multiple-pass removal-depletion by backpack electrofishing.

Prior to sampling, PG&E Hydro Generation reduced stream flow releases from Cresta and Rock Creek dams to levels that could be safely waded at the four sample sites. The study sites were isolated with ½-inch (1.27 mm) mesh block nets to prevent immigration or emigration of fish during sampling. Six shocking teams (i.e., one shocker and one netter) moved upstream in concert across a unified front during each sampling pass. The shockers used portable backpack electrofishers to stun fish, which were captured by the netters using either ⅛-inch or ¼-inch mesh dip nets. All captured fish were removed to one of several

available 5-gallon live buckets that were towed on small plastic tote-barges by additional netters. All live buckets were filled with river water and equipped with a small bait bucket aerator. Fish in the live buckets were periodically transferred to a ⅛-inch mesh netted live box located in the river outside of the study site and away from the electric field.

The battery-powered backpack electrofishers used during these surveys included Smith- Root® models 11A, 12A, 12B, and LR-24. A minimum of three passes of equal effort were made by the electrofishing teams within each reach. Teams maintained their same position across the stream channel for each pass. The target for the three-pass data was to provide a population estimate for rainbow trout with a standard error that was ten percent (or less) of the population estimate. After the third pass, the trout capture data was used to generate the population statistics on a laptop computer. If the standard error to population estimate ratio criterion was met, no additional passes were made. If it was not, another pass was made and the new estimate and standard error were evaluated.

Following each pass, captured fish were identified, measured and weighed. Prior to handling, fish were anesthetized in a weak CO2 solution using commercially available effervescent pain-relief tablets (two tablets: ¾ gallons of clean river water). Fish were measured to the nearest millimeter fork length (FL) [or total length (TL) for sculpin species] and weighed on an electronic scale. Fish smaller than 300 mm in length were typically weighed to the nearest 0.1 gram; larger fish were weighed to the nearest gram. Fish measurement data and notes were recorded on standardized data sheets. During processing, fish were inspected for any distinguishing marks (fin clips) or features (e.g., hook scars, deformed fins, tumors; fungus, etc.), which were noted on the data sheets. All mortalities were also noted on the data sheets.

The Rodgers Flat site contained a side channel area that was electrofished separately following each pass in the main channel. All sample effort, catches, and habitat data were recorded separately for the side channel and main channel areas.

Scale samples were taken from most captured trout for use in future age and growth determinations. Scales were removed from the right side between the dorsal fin and lateral line as specified in DeVries and Frie (1996). The scale samples were stored in labeled scale envelopes. Trout from which scale samples were taken were also noted on the data sheets to allow for cross referencing length/weight data in the event of potential errors, omissions or confusion from the notes on the scale envelopes.

After processing, all fish were placed in an aerated bucket of cool river water and allowed to recover. Fish in the recovery bucket were regularly transferred to a ⅛-inch mesh netted live box located in the river outside the study site. All fish were held in live boxes until fully recovered from the shocking and handling. After the completion of the survey, all fish were distributed back to size-appropriate habitat areas of the study site.

The length data was used to generate site-specific length-frequency histograms for each species. These plots show the size structure of the population, which tends to be related to the age structure of the specific population.

The multiple-pass capture data were used to generate a population estimate and 95 percent confidence interval for each species using the maximum-likelihood estimator from the software program MicroFish 3.0 (Van Deventer and Platts 1989). MicroFish 3.0 cannot provide a population estimate if only a single fish is captured from all passes combined, or if all the fish are captured on the first pass. In these rare cases, the Zippin estimator from the software program CAPTURE (White et al. 1978) was used to calculate the population estimate and associated error. Both software programs generate probability-of-capture estimates based upon capture patterns. The capture probability estimate, which varies between zero and one, is a measure of sampling efficiency, with values greater than 0.40 being generally indicative of effective sampling (White et al. 1982).

Fulton's Condition Factor (K) was calculated for rainbow trout using the formula of Bagenal and Tesch (1978). The condition factor compares the length and weight

relationship of individual fish to assess their physical condition (Everhart et al. 1975). Higher condition factors indicate heavier fish for a given length. A value of 1.0 is generally considered normal for a healthy population of trout.

The population estimate data was used to generate abundance and biomass estimates. The abundance estimates were standardized to common indices (fish/mile and fish/acre) to facilitate comparisons between unequal length/area sites within and between years and to allow for comparison with criteria listed in the SA. Biomass estimates for each species at each station were calculated as the product of the estimated fish population and the mean weight of that species captured during electrofishing divided by the surface area of the river at sampled at that site. Biomass estimates were also calculated using several indices (e.g. kilograms/hectare, pounds/acre) to facilitate comparison with earlier surveys and to allow for comparison with criteria listed in the SA.

Results

The electrofishing surveys of the two Rock Creek reaches of the NFFR were conducted on 12-13 October 2010. The two Cresta sites were surveyed the following week, 19-20 October 2010. Detailed plots of the stream flows in the Rock Creek Reach (Gage NF-57) and Cresta Reach (Gage NF-56) during the 2010 electrofishing surveys are presented in Figure 4.

On the morning of 11 October 2010 the release from Rock Creek Dam was reduced from 360 cfs to less than 50 cfs. The discharge recorded at Rock Creek stream gage (NF-57) during the two days of shallow-water electrofishing was stable and averaged 44 cfs. During the early evening of 13 October and following the completion of the Rock Creek Reach electrofishing surveys, the stream flow below Rock Creek Dam was raised back to a level in excess of 340 cfs, well above the SA normal year minimum flow of 260cfs and similar with the flow levels prior to the sampling effort.

550

500 NFFR - Rock Creek Reach Gage NF-57 450

400

350

(cfs) 300

250 Sample Rodgers Flat Site Sample Granite Creek Discharge 200

150

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0 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 11 October 12 October 13 October

550

500 NFFR - Cresta Reach Gage NF-56 450

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350 Sample Grizzly Creek Site 300 Sample Bear Ranch Creek Site 250

Discharge(cfs) 200

150

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0 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 6:00 12:00 18:00 0:00 18 October 19 October 20 October

Figure 4. Stream flow records for the Rock Creek (top) and Cresta (bottom) study reaches during the October 2010 backpack electrofishing survey. Preliminary records provided by PG&E.

The following week in the early morning of 18 October 2010, the release from Cresta Dam was reduced from 475 cfs to less than 90 cfs. The discharge recorded at Cresta Reach stream gage (NF-56) during the two days of shallow-water electrofishing was relatively stable and averaged 76 cfs. During the early evening of 20 October and following the completion of the Cresta Reach electrofishing surveys, the stream flow below Cresta Dam was raised back to a level in excess of 520 cfs, well above the SA normal year minimum flow of 325cfs and similar with the flow levels prior to the sampling effort.

Physical Site Data Collection

The habitat and water quality measurements were conducted at each site following the first electrofishing pass while the remaining crews were processing the captured fish. Copies of the actual data sheets are contained in Appendix B. A summary of the habitat measurements and variables are presented in Table 5.

By the time of mid-October sampling, water temperatures in the NFFR were relatively cool (<15°C [60°F]), while dissolved oxygen concentrations were relatively high (>8.0 mg/L) at most of the study sites (Table 5). This combination of moderate water temperature and high dissolved oxygen levels likely contributed to the low electrofishing/handling mortality noted during our 2010 surveys (1.4 percent for trout; 0.6 percent overall). Water conductivity was moderate (74 to 99μS/cm) at all the sites, making for ideal conditions for attracting and holding fish using electrofishing.

Table 5. Location of upstream boundary, date surveyed, and summary of habitat and water quality measurements for the four Rock Creek-Cresta shallow-water electrofishing sites sampled in October 2010. (The raw data from field notes contained in Appendix B).

Mean Mean Max Water Dissolved Dissolved Latitude/ Length Area Gradient Conductivity Date Width Depth Depth Temp pH Oxygen Oxygen Longitude (ft) (ft2) (%) (μS/cm) (ft) (ft) (ft) (°C) (mg/L) (% sat.)

Cresta Reach – NFFR below Bear Ranch Creek

39° 50’36”N/ 19 Oct 365 73.8 26,947.0 1.9 4.9 0.6 13.2 8.4 74.0 9.57 91.6 121° 23’54”W

Cresta Reach – NFFR below Grizzly Creek

39° 52’01”N/ 20 Oct 320 83.4 26,690.9 2.0 5.5 1.8 13.1 8.4 83.0 9.89 94.3 121° 22’47”W

Rock Creek Reach – NFFR below Granite Creek

39° 56’59”N/ 12 Oct 358 82.4 29,486.2 1.6 4.2 1.2 14.5 8.7 95.2 7.98 78.1 121° 18’02”W

Rock Creek Reach – NFFR at Rodgers Flat

Main channel 39° 57’46”N/ 13 Oct 235 64.8 15,221.6 1.9 3.7 0.6 14.1 8.2 99.2 10.70 104.6 121° 16’35”W

Side channel 39° 57’47”N/ 13 Oct 148 14.9 2,202.5 0.7 1.8 no data no data no data no data no data 121° 16’35”W

Bear Ranch Creek Site

The top of this 365-foot long site was located in the Cresta Reach about 211 feet downstream of the mouth of Bear Ranch Creek (Figure 3). During our survey, this site encompassed 26,947 ft2 (0.62 acres/0.25 hectares) and was predominantly run habitat (Tables 4 and 5). The site had a relatively low gradient (0.6 percent) and the substrate was dominated by boulder and cobble. Instream object cover (e.g., boulder and cobble elements) was identified as the dominant cover type. Small amounts (49 ft2) of suitable trout spawning gravels were noted in the low flow channel at this site during our survey.

Grizzly Creek Site

This 320-foot long site was located in the Cresta Reach about 0.5 miles downstream of the mouth of Grizzly Creek (Figure 3). During our survey, this site encompassed 26,691 ft2 (0.61 acres/0.25 hectares) and was classified as primarily a mixture of run and riffle habitats with some pocket water (Tables 4 and 5). The substrate in this relatively low gradient site (1.8 percent) was dominated by boulder and cobble. Instream object cover was identified as the dominant cover type. Relatively little trout spawning material, approximately 255 ft2 or <1 percent of the total surface area, was noted in the low flow channel at this site during our survey.

Granite Creek Site

This 358-foot long site was located in the Rock Creek Reach about 536 feet downstream of the mouth of Granite Creek (Figure 3). This study site was relatively wide and shallow and it possessed a split channel along half its length (Table 5). During our survey, this site encompassed 29,486 ft2 (0.68 acres/0.28 hectares) and was classified as primarily a mixture of run and riffle habitats (Tables 4 and 5). The substrate in this relatively low gradient site (1.2 percent) was dominated by boulder and cobble. Instream object cover was identified as the dominant cover type. Less than 20 ft2 of suitable trout spawning material was identified in the low flow channel at this site during our survey. This site was added to the

survey in 2005 since it more closely approximated the historical CDFG sample site and possessed more shallow-water habitat characteristics compared to the Indian Jim School site just downstream (which was not sampled in 2006 or 2010).

Rodgers Flat Site

This 235-foot long site was located in the Rock Creek Reach near Rodgers Flat (Figure 3). The top block net was about 370 feet downstream of the mouth of Milk Ranch Creek, while the bottom of the reach was about 20 feet upstream of the mouth of the new Milk Ranch Creek spawning channel outlet. The electrofishing site contained 148 feet of side channel habitat that was sampled separately from the main channel. The side channel was located at the bottom end of a substantial north bank side channel that entered the main channel 105 feet upstream of the bottom block net and extended beyond the upstream portion of the study site.

During our survey, the main channel area encompassed 15,222 ft2 (0.35 acres/0.14 hectares) and was classified primarily as pocket water habitat (Tables 4 and 5). The side channel area was 2,203 ft2 (0.05 acres/0.02 hectares) and was primarily shallow pool habitat. The main channel was relatively low gradient (0.6 percent). The streambed of both the main and side channel areas was almost exclusively made up of large boulder elements. These large boulders provided the dominant fish cover in both the main and side channel areas. Very few deposits of suitable trout spawning material (38 ft2, all in the side channel area) were identified in low flow channel at this site during our survey.

Electrofishing

The October 2010 survey collected a total of 1,496 fish from eight species (Table 6). Riffle sculpin were the most abundant species captured at all four sample sites and accounted for 65.6 percent of the overall total catch. Rainbow trout was the second most abundant species in the total catch (19.8 percent). Prickly sculpin (4.1 percent), hardhead (3.6 percent), Sacramento pikeminnow (3.1 percent), Sacramento sucker (2.1 percent) and smallmouth bass (1.6 percent) were relatively minor components of the overall catch. Only one brown trout was captured and it contributed less than 0.1 percent of the overall catch. Copies of the actual field data sheets are contained in Appendix C.

Table 6. Fish species collected at the four Rock Creek-Cresta Project shallow-water electrofishing sample sites, October 2010. Cresta Reach Rock Creek Reach Bear Grizzly Granite Rodgers Flat Total Fish Species Ranch Cr. Cr. Cr. Main Ch. Side Ch. Fish

Rainbow trout 73 104 69 45 5 296 Brown trout 0 1 0 0 0 1 Hardhead 3 0 49 2 0 54 Sacramento pikeminnow 2 1 42 1 0 46 Sacramento sucker 6 5 18 3 0 32 Smallmouth bass 18 3 1 2 0 24 Riffle sculpin 205 293 392 79 12 981 Prickly sculpin 14 38 10 0 0 62

Site Total 321 445 581 132 17 1,496

Scales were collected from 295 rainbow trout ranging in size from 63 to 424 mm FL during the 2010 survey. None of the scale samples were examined for this report. Previous work has suggested that mean length of rainbow trout at annulus II formation was significantly greater for years with higher minimum flows in the Rock Creek and Cresta reaches (CDFG 1988). A total of 1,275 rainbow trout scale samples have been collected in the four surveys conducted since 2004. The 2004-2006 and 2010 scale samples are archived and can be evaluated for future age/growth studies, as required.

Length-frequency analysis for rainbow trout shows that smaller size classes less than 152 mm FL (6 inches) dominated the populations at three of the four survey sites in 2010 (Figure 5). At the Bear Creek Site in the Cresta Reach, trout less than 152 mm in length made up 52% of the rainbow trout captured, although the mean FL for all trout captured was 186.6 mm (7.3 inches). At the Grizzly Creek Site in this reach, rainbow trout less than 152 mm FL made up 86% of the trout captured, with the mean FL length of all trout captured being 126.0 mm (5.0 inches). At the Granite Creek Site in the Rock Creek reach, trout less than 152 mm in length made up 67% of the total rainbow trout captured, with the mean FL of all trout captured being 146.5 mm (5.8 inches). Only at the Rodgers Flat Site did larger fish dominate the rainbow trout populations, with trout less than 152 mm in length making up only 30% of the total trout captured, with the mean FL of all trout captured being 204.4 mm (8.0 inches).

With no age-length analysis based on the October 2010 scales available, we relied on the ECORP (2003) scale analysis from the 2002 field data to assign the 2010 rainbow trout length data to various age class categories (Table 7). Since the 2002 age categories are discontinuous (i.e., what age class would a 150 mm FL fish at Bear Ranch Creek be, as it falls in between both the reported 1+ and 2+ data?), we constructed a composite and continuous age-length relationship from the 2002 data. It is a composite because it combines data from all four sites, and it is continuous since it extends the discontinuous size categories into continuous, non-over-lapping categories.

The composite age-length relationship from Table 7 was used to estimate the age distribution for rainbow trout captured during the October 2010 electrofishing survey (Table 8).

20 20

18 Cresta Reach 18 Cresta Reach NFFR below Bear Ranch Creek NFFR below Grizzly Creek 16 16 (n = 73; mean FL = 186.6 mm) (n = 104; mean FL = 126.0 mm) 14 14

12 12

10 10

8 8 Number Number ofFish Number Number ofFish 6 6

4 4

2 2

0 0 45 75 105 135 165 195 225 255 285 315 345 375 405 435 45 75 105 135 165 195 225 255 285 315 345 375 405 435 Fork Length (mm) Fork Length (mm) 20 20

18 Rock Creek Reach 18 Rock Creek Reach NFFR below Granite Creek 16 16 NFFR at Rodgers Flat (n = 69; mean FL = 146.5 mm) (n = 50; mean FL = 204.4 mm) 14 14

12 12

10 10

8 8 Number Number ofFish Number Number ofFish 6 6

4 4

2 2

0 0 45 75 105 135 165 195 225 255 285 315 345 375 405 435 45 75 105 135 165 195 225 255 285 315 345 375 405 435 Fork Length (mm) Fork Length (mm) Figure 5. Length-frequency data for rainbow trout captured during the October 2010 Rock Creek-Cresta electrofishing survey.

Table 7. Age-length data for rainbow trout captured at the four Rock Creek-Cresta electrofishing sites sampled in October 2002 (ECORP 2003) and TRPA composite age- length intervals. Size range in millimeters Cresta Reach Rock Creek Reach Age Class Bear Ranch Creek Grizzly Creek Indian Jim Rodgers Flat Composite 0+ 64-91 66-91 84-92 60 <95 1+ 97-129 93-146 160 94-123 95-160 2+ 202-312 167-258 220-248 162-290 161-299 3+ 318-355 300-353 291-353 326-364 300-360 4+ 361-385 383 >360

Table 8. Estimated rainbow trout age class distributions at the four Rock Creek-Cresta sites surveyed in October 2010 using the TRPA composite age-length intervals derived from the 2002 age-length analysis from ECORP (2003). Number of rainbow trout Cresta Reach Rock Creek Reach Age Class Bear Ranch Creek Grizzly Creek Indian Jim Rodgers Flat Total 0+ 11 21 11 7 50 1+ 26 71 36 11 144 2+ 26 9 19 22 76 3+ 7 3 1 7 18 4+ 3 0 2 3 8

Examination of the estimated age class distribution suggested that the normal and expected pattern of young-of-the-year (0+) fish dominating the late-fall trout populations was not observed at any of the sites (Table 8). Instead, the trout populations at all sites appeared to be dominated by fish other than the 2010 cohort. At the Grizzly Creek and Granite Creek sites, the age-length data suggested that 1+ fish (2009 cohort) composed the majority of the trout population, contributing over 68% and 52% of the total captures, respectively. At the Bear Ranch Creek Site, there was an equal representation of age 1+ and age 2+ trout (2009 and 2008 cohorts). At the Rodgers Flat Site, age 2+ sized fish (2008 cohort) dominated the local rainbow trout populations. Age 4+ rainbow trout (trout larger than 360 mm) were captured at three of the four Rock Creek-Cresta sites during the 2010 surveys.

Since 2002, downstream migrant trapping has periodically been conducted in several of the Rock Creek Cresta Project area tributaries including Opapee, Milk Ranch, Chambers, Granite, and Bucks creeks in the Rock Creek Reach and Grizzly Creek in the Cresta Reach. During the first five years of the program (2003-2006) captured migrants larger than 50 mm in length were given an adipose fin clip prior to their release into the NFFR. However, due to concerns over potential mortality issues, downstream migrants are no longer marked prior to their release below the trap sites (Stuart Running, personal communication). No adipose-clipped rainbow trout were captured at any of the four Rock Creek-Cresta sites during the 2010 surveys.

Inspection of the condition factor-frequencies indicate that the trout populations at all the sites are in good condition (Figure 6). The average condition factors for trout from the four study sites were all above 1.0, with only 0.34 percent (1 trout) of the calculated condition values less than this threshold.

The single brown trout captured at the Grizzly Creek Site, was 127 mm FL (Figure 7) and had a condition factor of 1.20, very similar to the average for the rainbow trout, and indicative of a healthy fish. This is the first brown trout captured in the shallow-water electrofishing surveys since the CDFG surveys in 1986.

Hardhead were captured at three of the four survey sites. No hardhead were captured at the Grizzly Creek site in the October 2010 survey. Unlike the 2006 survey when most of the hardhead captured in the shallow-water surveys were young-of-the-year fish less than 60 millimeters in length, most of the hardhead captured in October 2010 were larger juveniles greater than 70 millimeters in length (Figure 7). No adult-sized hardhead (≥300 mm) were captured at any of the shallow-water sites sampled. However, large adult hardhead were observed at nearby deep water pool habitats during the September 2010 dive count surveys (Allen and Gast 2011). Adult hardhead have been reported to prefer the deeper pool areas of streams (Moyle 2002).

Sacramento pikeminnow were present at all four shallow-water survey sites, though comparatively more were present at the Granite Creek site (Table 6). As was noted for hardhead, the length-frequency distributions show that young-of-the-year fish less than 60 millimeters in length were not particularly abundant among the captures and pikeminnow fry were only captured at one site, Granite Creek (Figure 8). Most of the pikeminnow captured at the four shallow-water electrofishing sites were older juvenile fish in the 100- 200 mm size range.

Sacramento sucker were captured at all four electrofishing sample sites in October 2010, but they contributed only a minor fraction of the total catch at each of the sites (Table 6). Multiple age classes were captured at all the sites (Figure 9). Unlike 2006, when young-of- the-year suckers less than 80 millimeters dominated not only the sucker population at all four sites, but the total catch at each site as well, in October 2010 sucker fry were relatively scarce and made up the majority of the sucker populations at only the two Cresta sites. No recently hatched sucker fry were captured at the Rodgers Flat site, including the side channel habitat. No large adult suckers greater than 350 mm (13.8 inches) in length were captured during the October 2010 shallow-water electrofishing surveys, though suckers larger than 380 mm (>15 inches) in length were observed at nearby deep water pool habitats during the September 2010 dive count surveys (Allen and Gast 2011).

Smallmouth bass were present at all four shallow-water electrofishing sites (Table 6). Most of the bass were young-of-the-year fish less than 90 mm in length (Figure 10). Two size classes, representing young-of-the-year and older juvenile bass in the 140-169 mm FL size class (probably one year old bass) were captured at the Bear Ranch Creek Site in the Cresta Reach and the Rodgers Flat Site in the Rock Creek Reach.

24 24 Cresta Reach Cresta Reach 21 NFFR below Bear Ranch Creek 21 NFFR below Grizzly Creek (n = 73; mean CF = 1.25) (n = 102; mean CF = 1.28) 18 18

15 15

12 12

9 9

Number Number ofFish Number ofNumber Fish

6 6

3 3

0 0 0.725 0.825 0.925 1.025 1.125 1.225 1.325 1.425 >=1.5 0.725 0.825 0.925 1.025 1.125 1.225 1.325 1.425 >=1.5 Condition Factor Condition Factor

24 24 Rock Creek Reach Rock Creek Reach 21 NFFR below Granite Creek 21 NFFR at Rodgers Flat (n = 69; mean CF = 1.20) (n = 50; mean CF = 1.23) 18 18

15 15

12 12

Number Number ofFish 9 9 Number ofFish

6 6

3 3

0 0 0.725 0.825 0.925 1.025 1.125 1.225 1.325 1.425 >=1.5 0.725 0.825 0.925 1.025 1.125 1.225 1.325 1.425 >=1.5 Condition Factor Condition Factor Figure 6. Condition factor-frequency data for rainbow trout captured during the October 2010 Rock Creek-Cresta electrofishing survey.

12 12 11 Brown trout 11 Hardhead 10 Cresta Reach 10 Cresta Reach NFFR below Bear Ranch Creek 9 NFFR below Grizzly Creek 9 (n = 1; Fork Length = 127 mm) (n = 3; mean FL = 103.7 mm) 8 8 7 7 6 6

5 5 Number of Fish of Number Number of Fish of Number 4 4 3 3 2 2 1 1 0 0 25 45 65 85 105 125 145 165 185 205 225 25 45 65 85 105 125 145 165 185 205 225 Fork Length (mm) Fork Length (mm)

12 12 11 Hardhead 11 Hardhead 10 Rock Creek Reach 10 Rock Creek Reach NFFR at Rodgers Flat 9 NFFR below Granite Creek 9 (n = 49; mean FL = 86.4 mm) (n = 2; mean FL = 70.5 mm) 8 8 7 7 6 6

5 5 Number of Fish of Number Number of Fish of Number 4 4 3 3 2 2 1 1 0 0 25 45 65 85 105 125 145 165 185 205 225 25 45 65 85 105 125 145 165 185 205 225 Fork Length (mm) Fork Length (mm)

Figure 7. Length-frequency data for brown trout (upper left) and hardhead captured during the October 2010 Rock Creek-Cresta electrofishing survey.

11 11 Cresta Reach 10 10 Cresta Reach NFFR below Bear Ranch Creek NFFR below Grizzly Creek 9 (n = 2; mean FL = 214.0 mm) 9 (n = 1; Fork Length = 125 mm) 8 8 7 7 6 6 5 5 4

4 Fish of Number Number of Fish of Number 3 3 2 2 1 1 0 0 25 45 65 85 105 125 145 165 185 205 225 245 265 285 305 25 45 65 85 105 125 145 165 185 205 225 245 265 285 305 Fork Length (mm) Fork Length (mm)

11 11 10 Rock Creek Reach 10 Rock Creek Reach NFFR below Granite Creek NFFR at Rodgers Flat 9 9 (n = 42; mean FL = 113.0 mm) (n = 1; Fork Length = 180 mm) 8 8 7 7 6 6 5 5 4

Figure 8. Length-frequency data for Sacramento pikeminnow captured during the October 2010 Rock Creek-Cresta electrofishing survey.

Riffle sculpin were captured at all four sample sites and represented the most abundant species in the catch at each of those sites (Table 6). The length-frequency data for this small benthic species suggest that there are three size classes (and presumably age classes) of fish are present at all the sites: 40-69 mm, 70-119 mm, and >120mm (Figure 11). Fish in the 70-119 mm size range (presumably one year old fish) dominated the sculpin population at all of the sample sites, contributing between 55 and 71 percent of the catch. Young-of-the-year fish in 40-69 mm size range made up most of the remaining populations (22 to 43 percent). Very few riffle sculpin over 120 mm in length were captured and contributed less than 1.5 percent of the riffle sculpin population at any of the sites.

Prickly sculpin were captured at both Cresta Reach sites and at the Granite Creek Site in the Rock Creek Reach and were only a minor component of the fish populations (Table 6). In the October 20101 survey prickly sculpin in the 70-119 size range (presumably one year old fish) dominated the prickly sculpin populations at the three sites they were captured (Figure 12). No prickly sculpin were captured at the Rodgers Flat site in 2010.

The MicroFish 3.0 (or CAPTURE) output, including the population estimates and associated statistics for each species at each site can be found in Appendix D. The model output is summarized below in Table 9.

The population estimates and their associated confidence intervals appear to be reasonably good for most species at most sites, especially for rainbow trout (Table 9). Our sampling goal of obtaining a standard error of the population estimate for rainbow trout that was ≤10 percent of the population estimate after three electrofishing passes was met at only two of the four sites. A fourth pass was required at the Bear Ranch Creek Site and five passes were required at the Granite Creek Site to meet this threshold for rainbow trout.

6 6

Cresta Reach Cresta Reach 5 NFFR below Bear Ranch Creek 5 NFFR below Grizzly Creek (n = 6; mean FL = 75.8 mm) (n = 5; mean FL = 110.4 mm) 4 4

3 3 Number of Fish of Number Number of Fish of Number 2 2

1 1

0 0 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 Fork Length (mm) Fork Length (mm)

6 6

Rock Creek Reach Rock Creek Reach 5 NFFR below Granite Creek 5 NFFR at Rodgers Flat (n = 18; mean FL = 130.6 mm) (n = 3; mean FL = 242.0 mm) 4 4

3 3 Number of Fish of Number Number of Fish of Number 2 2

1 1

0 0 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 Fork Length (mm) Fork Length (mm)

Figure 9. Length-frequency data for Sacramento sucker captured during the October 2010 Rock Creek-Cresta electrofishing survey.

6 6

Cresta Reach Cresta Reach 5 NFFR below Bear Ranch Creek 5 NFFR below Grizzly Creek (n = 18; mean FL = 83.6 mm) (n = 3; mean FL = 67.0 mm) 4 4

3 3 Number of Fish of Number Number of Fish of Number 2 2

1 1

0 0 45 55 65 75 85 95 105 115 125 135 145 155 165 175 45 55 65 75 85 95 105 115 125 135 145 155 165 175 Fork Length (mm) Fork Length (mm)

6 6

Rock Creek Reach Rock Creek Reach 5 NFFR below Granite Creek 5 NFFR at Rodgers Flat (n = 1; Fork Length = 60mm) (n = 2; mean FL = 103.5 mm) 4 4

3 3 Number of Fish of Number Number of Fish of Number 2 2

1 1

0 0 25 35 45 55 65 75 85 95 105 115 125 135 145 155 45 55 65 75 85 95 105 115 125 135 145 155 165 175 Fork Length (mm) Fork Length (mm)

Figure 10. Length-frequency data for smallmouth bass captured during the October 2010 Rock Creek-Cresta electrofishing survey.

105 105

Cresta Reach Cresta Reach 90 90 NFFR below Bear Ranch Creek NFFR below Grizzly Creek (n = 205; mean TL = 80.3 mm) (n = 293; mean TL = 77.8 mm) 75 75

60 60

45 45

Number of Fish of Number Number of Fish of Number 30 30

15 15

0 0 35 45 55 65 75 85 95 105 115 125 135 35 45 55 65 75 85 95 105 115 125 135 Total Length (mm) Total Length (mm)

105 105 Rock Creek Reach Rock Creek Reach 90 NFFR below Granite Creek 90 NFFR at Rodgers Flat (n = 392; (n = 91; mean TL = 93.8 mm) 75 mean TL = 81.6 mm) 75

60 60

45 45

Number of Fish of Number Number of Fish of Number 30 30

15 15

0 0 35 45 55 65 75 85 95 105 115 125 135 35 45 55 65 75 85 95 105 115 125 135 Total Length (mm) Total Length (mm)

Figure 11. Length-frequency data for riffle sculpin captured during the October 2010 Rock Creek-Cresta electrofishing survey.

Less confidence and larger potential errors were generally associated with the estimates derived for the small juvenile minnows at the Granite Creek site in the Rock Creek Reach (Table 9). Large confidence intervals and lower relative probabilities of capture were also generally observed for sculpin. Despite sculpin being abundant at most sites, their benthic nature, cryptic coloration, and tendency to sink quickly to the bottom made them difficult to capture at all of the study sites, especially in the deeper areas, or among the interstitial spaces that dominated the streambed at all the sample sites.

The relative population abundance expressed as a percent of the total population estimate for all species combined by site is presented in Figure 13. At all four survey sites, riffle sculpin dominated the October 2010 estimated fish population abundance estimates, contributing 66 to 84 percent of the estimated abundance of all fishes. At the Bear Ranch Creek and Grizzly Creek sites in the Cresta Reach and at the Rodgers Flat site in the Rock Creek Reach rainbow trout was the second most abundant species in the site-wide abundance estimate. At the Granite Creek Site, irregular depletion rates for hardhead resulted in a large population estimate (with poor confidence) for this species. This poor estimate for hardhead resulted in the estimated contribution of 27 percent of the site-wide population estimate (Figure 13), even though hardhead made up less than 9 percent of the actual total catch (Table 6). Sacramento suckers which dominated the population estimates at all the sites in the 2006 survey (Salamunovich 2007b) made up less than 2 percent of the estimated populations at any of the sites in the October 2010 survey.

Another notable change from the 2006 survey was evident at the Rodgers Flat side channel area. In 2006 a large proportion of the fish population in this side channel area was made up of small suckers, hardhead, and pikeminnow (Salamunovich 2007b). In the October 2010 survey, not a single sucker or minnow was captured in the side channel.

10 10 9 Cresta Reach 9 Cresta Reach NFFR below Bear Ranch Creek NFFR below Grizzly Creek 8 8 (n = 14; mean TL = 93.4 mm) (n = 38; mean TL = 84.2 mm) 7 7 6 6 5 5

4 4 Number of Fish of Number Number of Fish of Number 3 3 2 2 1 1 0 0 35 45 55 65 75 85 95 105 115 125 135 35 45 55 65 75 85 95 105 115 125 135 Total Length (mm) Total Length (mm)

10 9 Rock Creek Reach NFFR below Granite Creek 8 (n = 10; mean TL = 81.1 mm) 7 6 5 4

Number of Fish of Number 3 2 1 0 35 45 55 65 75 85 95 105 115 125 135 Total Length (mm)

Figure 12. Length-frequency data for prickly sculpin captured during the October 2010 Rock Creek-Cresta electrofishing survey. No prickly sculpin were collected at Rodgers Flat in 2010.

Table 9. Multiple pass removal-depletion patterns and electrofishing statistics for fish species captured at the four shallow-water Rock Creek-Cresta sites sampled using backpack electrofishers in October 2010. Unless noted, all estimates were generated using the program MicroFish 3.0. Total Population Probability of Species Removal Pattern Catch Estimate Capture Estimate Cresta Reach - NFFR below Bear Ranch Creek Rainbow trout 29 – 27 – 10 – 7 73 83 13 0.403 0.139 Hardhead 1 – 2 – 0 – 0 3 3 2 0.600 1.221 Sacramento pikeminnow 2 – 0 - 0 – 0 2 2 1* 0.9997 Sacramento sucker 4 - 1 – 0 – 1 6 6 1 0.600 0.516 Smallmouth bass 9 - 3 – 4 – 2 18 19 5 0.462 0.282 Riffle sculpin 77 - 64 – 31 – 33 205 275 53 0.289 0.092 Prickly sculpin 4 – 3 – 4 – 3 14 27 53 0.163 0.421 Cresta Reach - NFFR below Grizzly Creek Rainbow trout 55 – 31 – 18 104 125 22 0.444 0.144 Brown trout 1 – 0 – 0 1 1 1* 0.9996 Sacramento pikeminnow 1 – 0 – 0 1 1 1* 0.9996 Sacramento sucker 2 – 3– 0 5 5 2 0.625 0.729 Smallmouth bass 1 – 1 – 1 3 3 5 0.500 1.823 Riffle sculpin 145 – 80 – 68 293 412 78 0.338 0.098 Prickly sculpin 17 – 12 – 9 38 55 33 0.319 0.283 Rock Creek Reach - NFFR below Granite Creek Rainbow trout 19 – 27 - 11 – 8 – 4 69 79 13 0.332 0.125 Hardhead 12 – 1 - 14 – 4 – 18 49 245 1,005 0.043 0.192 Sacramento pikeminnow 10 – 11 - 8 – 5 – 8 42 79 80 0.140 0.190 Sacramento sucker 12 – 0 - 4 – 0– 2 18 18 2 0.529 0.229 Smallmouth bass 0 – 1 - 0 – 0 – 0 1 1 1* 0.4998 Riffle sculpin 134 – 100 - 76 – 53– 29 392 475 43 0.294 0.053 Prickly sculpin 7 – 2 - 0 – 1 – 0 10 10 0 0.667 0.297 Rock Creek Reach - NFFR at Rodgers Flat – Main Channel Rainbow trout 35 – 6 – 4 45 45 2 0.763 0.134 Hardhead 0 – 1 – 1 2 2 24 0.400 7.945 Sacramento pikeminnow 1 – 0 – 0 1 1 1* 0.9996 Sacramento sucker 3 – 0 – 0 3 3 1* 0.9998 Smallmouth bass 1 – 1 – 0 2 2 5 0.667 4.883 Riffle sculpin 39 – 23 – 17 79 105 33 0.369 0.182 Rock Creek Reach - NFFR at Rodgers Flat – Side Channel Rainbow trout 4 – 0 – 1 5 5 1 0.714 0.616 Riffle sculpin 5 – 2 – 5 12 27 78 0.174 0.612

* estimates from program CAPTURE

Figure 13. Relative species abundance presented as a percentage of the total population estimate at each of the Rock Creek-Cresta study sites during the October 2010 shallow-water electrofishing survey. RBT = rainbow trout; BRN = brown trout; HH = hardhead; PKM = Sacramento pikeminnow; SMB = smallmouth bass; RFS = riffle sculpin; PKS = prickly sculpin.

The various site-specific biomass estimates (and associated confidence intervals) derived from the population data and the mean weight for each fish species are presented in Table 10. Rainbow trout dominated the fish biomass estimates at both the Cresta Reach sites, contributing 79 and 56 percent of the total estimated fish biomass at the Bear Ranch and Grizzly sites, respectively (Figure 14). At both these Cresta Reach study sites, riffle sculpin were the second largest contributor to the estimated biomass, making up about 14 percent at the Bear Ranch Site and 35 percent of the estimated biomass at the Grizzly Creek Site. Again, the greatest change in these two sites compared to the 2006 biomass estimates is the change in the sucker biomass. In 2006, suckers contributed over 83 percent of the estimated biomass at both Cresta shallow-water electrofishing sites; in the October 2010 survey, suckers made up less than 1 percent of the estimated biomass at the Bear Ranch Creek Site and less than 4 percent of the estimated biomass at the Grizzly Creek Site.

The fish biomass appeared to be more evenly distributed among several species at the Granite Creek electrofishing sites (Figure 14). At this site, rainbow trout, riffle sculpin, hardhead, and pikeminnow contributed 38, 26, 18, and 12 percent of the total estimated biomass, respectively. The hardhead biomass estimate should not be considered a reliable estimate since the underlying population estimate for this minnow was quite poor and contributed to the high biomass estimate (and excessively large confidence interval) for this species.

In the main channel area of the Rodgers Flat Site in the Rock Creek Reach, rainbow trout dominated the estimated fish biomass, with over 79 percent of the total (Figure 14). Riffle sculpin and sucker contributed most of the remaining estimated biomass in the main channel area, with 13 and 7 percent of the total, respectively.

At the Rodgers Flat Site side channel area, riffle sculpin contributed 89 percent of the total estimated biomass and rainbow trout made up the remaining 11 percent (Figure 14).

Table 10. Mean weights and biomass estimates (± 95% confidence intervals) by species based upon mean weights of captured fish, multiple pass removal-depletion population estimates, and the physical dimensions of the four shallow-water Rock Creek- Cresta sites sampled using backpack electrofishers in October 2010.

Mean Biomass Estimate Biomass weight Reach Biomass Biomass Estimate Biomass Estimate (Pounds/mile) Biomass Estimate Estimate Species (grams) Estimate (Kg) (Kg/300 feet) (Kg/mile) (Kg/hectare) (Pounds/acre)

Cresta Reach - NFFR below Bear Ranch Creek

Rainbow trout 144.89 12.03 1.88 9.88 1.55 173.96 27.25 383.50 60.07 48.04 7.52 42.86 6.71 Hardhead 46.33 0.14 0.09 0.1142 0.0762 2.01 1.34 4.43 2.95 0.56 0.37 0.50 0.33 Sacramento pikeminnow 157.60 0.32 0.16 0.2591 0.1295 4.56 2.28 10.05 5.03 1.26 0.63 1.12 0.56 Sacramento sucker 12.25 0.07 0.01 0.0604 0.0101 1.06 0.18 2.34 0.39 0.29 0.05 0.26 0.04 Smallmouth bass 14.73 0.28 0.07 0.2300 0.0605 4.05 1.07 8..92 2.35 1.12 0.29 1.00 0.26 Riffle sculpin 7.85 2.16 0.42 1.7743 0.3420 31.23 6.02 68.84 13.27 8.62 1.66 7.69 1.48 Prickly sculpin 11.31 0.31 0.60 0.2510 0.4927 4.42 8.67 9.74 19.12 1.22 2.39 1.09 2.14 Total 15.30 3.24 12.5733 2.6591 221.29 46.80 487.84 103.17 61.10 12.92 54.51 11.53

Cresta Reach - NFFR below Grizzly Creek

Rainbow trout 42.28 5.29 0.93 4.95 0.87 87.20 15.35 192.24 33.83 21.31 3.75 19.01 3.35 Brown trout 24.60 0.02 0.02 0.02 0.02 0.41 0.41 0.89 0.89 0.10 0.10 0.09 0.09 Sacramento pikeminnow 17.60 0.02 0.02 0.02 0.02 0.29 0.29 0.64 0.64 0.07 0.07 0.06 0.06 Sacramento sucker 63.12 0.32 0.13 0.30 0.12 5.21 2.08 11.48 4.59 1.27 0.51 1.14 0.45 Smallmouth bass 4.93 0.01 0.03 0.01 0.02 0.24 0.41 0.54 0.90 0.06 0.10 0.05 0.09 Riffle sculpin 7.94 3.27 0.62 3.07 0.58 53.98 10.22 118.99 22.53 13.19 2.50 11.77 2.23 Prickly sculpin 8.98 0.49 0.30 0.46 0.28 8.15 4.89 17.97 10.78 1.99 1.20 1.78 1.07 Total 9.42 2.04 8.83 1.91 155.48 33.64 342.75 74.16 38.00 8.22 33.90 7.34

Rock Creek Reach - NFFR below Granite Creek

Rainbow trout 67.97 5.37 0.88 5.00 0.74 79.19 13.03 174.58 28.73 19.60 3.23 17.49 2.88 Hardhead 10.49 2.57 10.5425 2.15 8.83 37.90 155.49 83.56 342.77 9.38 38.48 8.37 34.33 Sacramento pikeminnow 21.63 1.71 1.7304 1.43 1.45 25.20 25.52 55.56 56.26 6.24 6.32 5.56 5.64 Sacramento sucker 41.71 0.75 0.0834 0.63 0.07 11.07 1.23 24.41 2.71 2.74 0.30 2.45 0.27 Smallmouth bass 2.40 0.002 0.002 0.002 0.002 0.04 0.04 0.08 0.08 0.01 0.01 0.01 0.01 Riffle sculpin 7.64 3.63 0.33 3.04 0.28 53.52 4.85 117.99 10.68 13.25 1.20 11.82 1.07 Prickly sculpin 7.99 0.08 0.0 0.07 0.0 1.18 0.00 2.60 0.000 0.29 0.00 0.26 0.00 Total 14.11 13.57 11.82 11.37 208.11 200.15 458.78 441.23 51.51 49.54 45.95 44.20

Rock Creek Reach - NFFR at Rodgers Flat (Main Channel)

Rainbow trout 187.80 8.45 0.38 10.79 0.48 189.88 8.44 418.59 18.60 59.76 2.66 53.31 2.37 Hardhead 5.30 0.01 0.13 0.01 0.16 0.24 2.86 0.53 6.30 0.08 0.90 0.07 0.80 Sacramento pikeminnow 53.90 0.05 0.05 0.07 0.07 1.21 1.21 2.67 2.67 0.38 0.38 0.34 0.34 Sacramento sucker 246.33 0.74 0.25 0.94 0.31 16.60 5.53 36.60 12.20 5.23 1.74 4.66 1.55 Smallmouth bass 26.90 0.05 0.13 0.07 0.17 1.21 3.02 2.66 6.66 0.38 0.95 0.34 0.85 Riffle sculpin 12.68 1.33 0.42 1.70 0.53 29.91 9.40 65.95 20.73 9.41 2.96 8.40 2.64 Total 10.64 1.36 13.58 1.73 239.05 30.47 526.99 67.16 75.24 9.59 67.12 8.55

Rock Creek Reach - NFFR at Rodgers Flat (Side Channel)

Rainbow trout 7.22 0.04 0.01 0.07 0.01 1.29 0.26 2.84 0.57 1.76 0.35 1.57 0.31 Riffle sculpin 10.60 0.29 0.83 0.58 1.68 10.21 29.50 22.51 65.03 13.99 40.41 12.48 36.05 Total 0.32 0.83 0.65 1.69 11.50 29.75 25.35 65.59 15.75 40.76 14.05 36.36

Figure 14. Relative species biomass presented as a percentage of the total biomass estimate at each of the Rock Creek-Cresta study sites during the October 2010 shallow- water electrofishing survey. RBT = rainbow trout; BRN = brown trout; HH = hardhead; PKM = Sacramento pikeminnow; SMB = smallmouth bass; RFS = riffle sculpin; PKS = prickly sculpin.

In terms of standardized biomass indices, the Rodgers Flat main channel site had the largest overall fish biomass estimate with 527 pounds/mile and 67.1 pounds/acre (Table 10). The side channel area biomass indices were 25.4 pounds/mile and 14.1 pounds/acre. The biomass indices for rainbow trout in the main channel area at this site were 418.6 pounds/mile and 53.3 pounds/acre. The rainbow tout biomass indices for the side channel area were negligible in comparison, at 2.8 pounds/mile and 1.6 pounds/acre. Combined total fish biomass estimates for both channels at this site were 542.7 pounds/mile and 60.4 pounds/acre. The combined main channel side channel rainbow trout indices were 420.4 pounds/mile and 46.8 pounds/acre.

The Bear Ranch Creek site had the second highest total fish estimated biomass indices, with 487.4 pounds/mile and 54.5 pounds/acre (Table 10). The biomass indices for rainbow trout at this site were 383.5 pounds/mile and 42.9 pounds/acre.

The Granite Creek Site had the third highest total fish biomass indices, with 458.8 pounds/mile and 46 pounds/acre (Table 10). The biomass indices for rainbow trout at this site were 174.6 pounds/mile and 17.5 pounds/acre.

The Grizzly Creek Site had the lowest overall fish biomass indices of the four sites, with estimates of 342.8 pounds/mile and 33.9 pounds/acre. The biomass indices for rainbow trout at this site were 192.2 pounds/mile and 19.0 pounds/acre.

Discussion

The October 2010 fish population sampling in the Rock Creek and Cresta reaches of the NFFR demonstrated that under reduced flow conditions multiple-pass removal-depletion sampling using electrofishing techniques can produce resident fish population estimates in shallow-water habitat with tight confidence intervals and a high probability of accuracy. The electrofishing survey showed the fall 2010 resident fish population in the shallow- water habitats of the Project area to be numerically dominated by riffle sculpin. However

in terms of biomass, rainbow trout were the dominant fish species at all four shallow-water electrofishing sites. These results are similar to the abundance and biomass patterns noted in the October 2004 shallow-water electrofishing survey (Salamunovich 2005).

Comparison of the present survey results with other recent surveys demonstrates some interesting between year differences. We have limited our comparisons to those made at roughly equivalent sample sites, which include the 1986 CDFG (CDFG 1988), the 2002 ECORP (ECORP 2003), and the 2004-2006 TRPA (Salamunovich 2005, 2006, and 2007b) surveys. Earlier surveys (Flint 1980; Moyle et al. 1983; CDFG 1988) included additional and different sample areas and some employed different sample methods and will not be discussed in this report. In our 2005 survey we added the Granite Creek site as a comparable site to the 1986 CDFG “between James Lee Campground and School” site, and so have limited our comparison to these two surveys.

A single juvenile brown trout was captured in the October 2010 survey at the Grizzly Creek Site. This is the only confirmed brown trout captured in the NFFR electrofishing since the CDFG 1986 electrofishing survey (Table 11). It should be noted that brown trout were stocked in the Project area several times during the five year period from 1980 through 1984 (CDFG 1988).

Small, self-sustaining populations of this non-native trout still occur in the basin, though mainly in the NFFR tributaries including the Bucks and Grizzly creek basins (Salamunovich and Berg 2002a, 2002b; Salamunovich 2007a, 2009) and in the mainstem NFFR upstream of the Project area and upstream of Belden Forebay (Stuart Running, personal communication). Brown trout have occasionally, but infrequently, been captured in downstream migrant traps operated in Chambers and Opapee creeks (Mike Kossow, personal communication). While brown trout have been occasionally documented in the NFFR in Rock Creek-Cresta Project area during recent creel surveys (Garcia and Associates 2003; Meadowbrook Conservation Services 2005, 2006, 2010), fish displacement margin count surveys (Salamunovich 2004a, 2004b), and dive count surveys

(Mark Allen, unpublished data) they appear to be relatively rare in the Rock Creek-Cresta reaches of the NFFR.

Our October 2010 estimates showed about a 50 percent decline in rainbow trout population abundance levels from those observed in October 2006 survey at three of the four sites (Tables 11, 12, and 13). Only at the Grizzly Creek Site in the Cresta Reach was the 2010 rainbow trout abundance estimate comparable to that noted in 2006. The 2010 rainbow trout abundance estimates appear to be more comparable to the fall 1986 and 2004 estimates. However, it should be noted that the 1986 data included hatchery trout, while the more recent data (2002, 2004-2006) was based solely on wild trout.

This general lower abundance of rainbow trout in the 2010 electrofishing data compared to the 2006 electrofishing survey was also noted in the snorkel survey results. Preliminary results indicate a 25 percent decrease for rainbow trout in the 2010 dive survey counts compared to the levels noted in the 2006 survey (Allen and Gast 2011).

Inspection of the mean weight data for rainbow trout captured during the electrofishing surveys shows that there was an increase in the mean weight for rainbow trout at all four sites in 2010 compared to the last survey in 2006 (Table 11). In fact, the mean weights are more comparable to those observed in 2002 and 2005 surveys. This increase in mean weight of rainbow trout noted in the 2010 survey compared to the 2006 survey is due to a larger proportion of one and two year old trout among the capture data (Table 12). Conversely, in 2006 there was a larger proportion of smaller young-of-the-year trout at most of the survey sites. A comparison of the length frequency data from the Rock Creek and Cresta reaches for these recent surveys clearly shows the relatively large proportion of rainbow trout larger than 95 mm (age 1 and older fish) in length in the 2010 surveys (Figures 15 and 16) compared to 2006. The large proportion of rainbow trout fry (fish smaller than 95 mm in length) noted in the 2006 survey were not evident in the 2010 data or in any of the more recent 2002-2005 surveys, and in fact have not been seen since the

1986 surveys. This general lack of rainbow trout fry was especially evident in the Rock Creek reach during the 2002-2005 surveys.

Despite the overall decline in rainbow trout abundance in 2010 compared to 2006 at three of the four shallow-water electrofishing sites (Tables 13 and 14), there was actually an increase in biomass at three of the sites (Bear Ranch Creek, Grizzly Creek and Rodgers Flat) over this same period (Tables 15 and 16). The fourth site, Granite Creek Site showed no change in biomass in 2010, despite over a 45 percent decline in abundance compared to 2006. In fact, the rainbow trout biomass estimates for the Bear Ranch Creek Site in 2010 (385.3 pounds/mile, or 42.9 pounds/acre) were the highest recorded for the past 25 years of record. The 2010 Rodgers Flat Site biomass estimates were the second highest on record.

These anomalous results for rainbow trout, decreases in abundance and increases in biomass, evident in the 2010 shallow-water electrofishing survey compared to 2006 were due to the size/age structure of the rainbow trout populations at these survey sites. In 2006 there were more, but smaller rainbow trout, while in 2010 there were fewer, but larger rainbow trout (Table 11). As the length frequency data in Figures 15 and 16 indicates, the 2006 survey rainbow trout population was dominated by small young-of-the-year fry , whereas the 2010 populations were dominated by larger one and two year old trout.

Preliminary results from the 2010 dive count survey results (Allen and Gast 2011) support the decline in rainbow trout fry in the Rock Creek-Cresta Project area, as noted in this report. . The 2006 dive surveys counted 9.2 rainbow trout fry per 1,000 feet of fry lane surveyed in both the Rock Creek and Cresta reaches of the NFFR, while the preliminary 2010 survey counts for rainbow trout fry were only 2.6 fish per 1,000 feet of fry lane surveyed, a 72 percent decline in abundance levels noted in 2006.

Table 11. Population estimate and mean weight summary for fish species captured during shallow-water electrofishing surveys at the five Rock Creek-Cresta sites sampled since 1986.

Site Population Estimate (N) Mean Weight (grams) 1986 2002 2004 2005 2006 2010 1986 2002 2004 2005 2006 2010 Brown trout Bear Cr. 1 0 0 0 0 0 52.0 ------Grizzly Cr. 0 0 0 0 0 1 ------24.6 Indian Jim NS 1 0 0 0 NS NS NS ------NS NS Granite Cr. 0 NS NS 0 0 0 0 NS NS ------Rodgers Flat 1 0 0 0 0 0 795.0 ------Rainbow trout Bear Cr. 92 2 27 110 42 157 83 40.6 169.0 76.4 163.7 34.4 144.9 Grizzly Cr. 144 2 86 154 82 121 125 35.0 67.7 51.4 37.1 21.7 42.3 Indian Jim NS 23 15 29 NS NS NS 239.3 280.7 299.2 NS NS Granite Cr. 184 2 NS NS 93 167 79 19.0 NS NS 92.7 31.2 68.0 Rodgers Flat 93 2 33 86 42 102 50 24.7 164.4 112.3 107.8 41.8 169.7 Hardhead Bear Cr. 195 33 87 0 175 3 1.0 2.6 1.5 --- 10.3 46.3 Grizzly Cr. 24 1 1 113 60 0 0.7 1.4 1.4 0.8 0.5 --- Indian Jim NS 130 96 85 NS NS --- 49.9 18.5 301.2 NS NS Granite Cr. 128 NS NS 355 123 245 2.1 NS NS 9.5 2.1 10.5 Rodgers Flat 68 0 16 8 42 2 1.1 --- 14.6 9.6 16.4 5.3 Sacramento pikeminnow Bear Cr. 76 43 13 2 17 2 2.7 6.9 31.0 0.8 0.8 157.6 Grizzly Cr. 54 6 4 272 56 1 1.1 5.7 6.4 1.2 22.6 17.6 Indian Jim NS 39 22 27 NS NS NS 32.9 21.2 48.3 NS NS Granite Cr. 404 NS NS 72 431 79 1.5 NS NS 10.3 4.8 21.6 Rodgers Flat 75 16 6 5 34 1 11.4 26.1 21.4 85.8 42.7 53.9 Sacramento sucker Bear Cr. 679 15 91 174 1,328 6 65.8 6.5 6.9 4.8 35.7 12.3 Grizzly Cr. 356 17 54 378 734 5 2.5 134.8 75.5 2.6 67.3 63.1 Indian Jim NS 44 79 245 NS NS NS 731.1 679.3 719.6 NS NS Granite Cr. 1,770 NS NS 55 765 18 21.5 NS NS 60.4 4.2 41.7 Rodgers Flat 384 6 13 8 258 3 85.2 443.8 93.2 60.2 9.4 246.3 Smallmouth bass Bear Cr. 1 13 28 116 13 19 14.0 22.3 --- 6.5 17.8 14.7 Grizzly Cr. 0 0 4 10 1 3 ------12.8 67.1 4.9 Indian Jim NS 0 2 4 NS NS ------8.45 NS NS Granite Cr. 0 NS NS 0 0 1 --- NS NS ------2.4 Rodgers Flat 0 1 4 5 2 2 --- 14.4 --- 9.1 48.1 26.9 Sculpin 3 Bear Cr. 25 50 522 115 383 302 20.7 10.4 6.6 9.9 5.5 8.1 Grizzly Cr. 2 258 522 280 239 467 22.0 8.9 6.7 10.1 6.5 8.1 Indian Jim NS 141 152 65 NS NS NS 9.1 3.7 7.0 NS NS Granite Cr. 279 NS NS 371 669 485 4.6 NS NS 9.7 5.3 7.7 Rodgers Flat 70 46 67 70 140 130 11.1 13.4 9.8 11.4 6.4 12.4 1 NS denotes no sampling “---“ indicates no weight value since no fish were captured in this survey 2 1986 DFG rainbow trout data includes hatchery fish 3 1986 DFG data did not identify sculpin to species

Table 12. Estimated rainbow trout age class distributions at the five Rock Creek-Cresta sites surveyed in 2002 through 2010, based upon the TRPA composite age- length intervals derived from the 2002 age-length analysis from ECORP (2003). Age Class 2002 2004 2005 2006 2010 Cresta Reach – NFFR below Bear Ranch Creek 0+ 6 33 13 78 11 1+ 5 24 3 31 26 2+ 11 26 12 14 26 3+ 2 5 7 4 7 4+ 2 1 3 0 3 Cresta Reach – NFFR below Grizzly Creek 0+ 10 37 34 46 21 1+ 45 79 24 48 70 2+ 17 15 13 3 9 3+ 4 8 1 2 3 4+ 1 0 0 0 0 Rock Creek Reach – NFFR at Indian Jim School 0+ 2 0 0 NS 1 NS 1+ 1 2 0 NS NS 2+ 6 5 11 NS NS 3+ 10 6 12 NS NS 4+ 0 2 2 NS NS Rock Creek Reach – NFFR below Granite Creek 0+ NS NS 16 76 11 1+ NS NS 28 50 36 2+ NS NS 35 13 19 3+ NS NS 7 3 1 4+ NS NS 0 0 2 Rock Creek Reach – NFFR at Rodgers Flat 0+ 1 2 2 32 7 1+ 4 35 13 44 11 2+ 20 41 23 11 22 3+ 3 7 2 3 7 4+ 0 0 0 0 3 All Sites 0+ 19 72 65 232 50 1+ 55 140 68 173 143 2+ 54 87 94 41 76 3+ 19 26 29 12 18 4+ 3 3 5 0 8 1 NS denotes no sampling

Table 13. Standardized abundance estimates (number per mile) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986. Species 1986 2002 2004 2005 2006 2010 Cresta Reach – NFFR below Bear Ranch Creek Brown trout 14.4 0 0 0 0 0 Rainbow trout 1,322.0 395.0 1,570.6 592.9 2,170.1 1,200.7 Hardhead 2,802.0 482.8 1,242.2 0 2,418.8 43.4 Sac. pikeminnow 1,092.1 629.1 185.6 28.2 235.0 28.9 Sac. sucker 9,756.7 219.5 1,299.3 2,456.5 18,355.6 86.8 Smallmouth bass 14.4 190.2 399.8 1,637.7 179.7 274.8 Sculpin 359.2 731.5 7,453.1 1,623.5 5,293.8 4,368.7 All fish 15,360.6 2,648.1 12,150.6 6,338.8 28,653.0 6,003.3 Cresta Reach – NFFR below Grizzly Creek Brown trout 0 0 0 0 0 16.5 Rainbow trout 2,461.9 1,537.8 2,710.4 1,428.9 2,101.6 2,062.5 Hardhead 415.3 17.9 17.6 1,969.1 1,042.1 0 Sac. pikeminnow 934.5 107.3 70.4 4,739.8 972.6 16.5 Sac. sucker 6,160.5 304.0 950.4 6,586.9 12,748.4 82.5 Smallmouth bass 0 0 70.4 174.3 17.4 49.5 Sculpin 34.61 4,613.5 9,187.2 4,879.2 4,151.1 7,705.5 All fish 10,036.8 6,580.4 13,006.4 19,778.2 21,033.2 9,933.0 Rock Creek Reach – NFFR at Indian Jim School Rainbow trout NS 1 406.8 269.4 497.1 NS NS Hardhead NS 2,299.1 1,724.1 1,457.1 NS NS Sac. pikeminnow NS 689.7 395.1 462.9 NS NS Sac. sucker NS 778.1 1,418.8 4,200.0 NS NS Smallmouth bass NS 0 35.92 68.6 NS NS Sculpin NS 2,493.6 2,729.8 1,114.3 NS NS All fish NS 6,667.3 6,573.1 7,800.0 NS NS Rock Creek Reach – NFFR below Granite Creek Rainbow trout 2,667.7 NS NS 1,395.0 2,593.4 1,165.1 Hardhead 1,855.8 NS NS 5,325.0 1,910.1 3,613.4 Sac. pikeminnow 5,857.4 NS NS 1,080.0 6,693.2 1,165.1 Sac. sucker 25,622.5 NS NS 825.0 11,880.0 265.5 Smallmouth bass 0 NS NS 0 0 14.7 Sculpin 4,045.1 NS NS 5,565.0 10,389.2 7,153.1 All fish 40,088.6 NS NS 14,190.0 33,465.9 13,377.0 Rock Creek Reach – NFFR at Rodgers Flat Brown trout 23.32 0 0 0 0 0 Rainbow trout 2,169.1 829.8 1,988.6 960.0 2,351.8 1,123.4 Hardhead 1,586.0 0 365.7 182.9 968.4 44.9 Sac. pikeminnow 1,749.3 402.3 137.1 114.3 783.9 22.5 Sac. sucker 8,956.4 150.9 297.1 182.9 5,948.6 67.4 Smallmouth bass 0 25.2 91.4 114.3 46.1 44.9 Sculpin 1,632.7 1,156.7 1,531.4 1,600.0 3,227.9 2,920.9 All fish 16,116.8 2,564.9 4,411.4 3,154.3 13,326.8 4,224.0 1 NS denotes no sampling

Table 14. Standardized abundance estimates (number per acre) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986. Species 1986 2002 2004 2005 2006 2010 Cresta Reach – NFFR below Bear Ranch Creek Brown trout 2.3 0 0 0 0 0 Rainbow trout 207.8 43.6 173.4 67.8 253.1 134.2 Hardhead 440.4 53.3 137.1 0 282.2 4.8 Sac. pikeminnow 171.6 69.4 20.5 3.2 27.4 3.2 Sac. sucker 1,533.4 24.2 143.4 280.7 2,141.1 9.7 Smallmouth bass 2.3 21.0 44.1 187.2 21.0 30.7 Sculpin 56.5 80.7 822.7 185.5 617.5 488.2 All fish 2,414.1 292.3 1,341.3 724.4 3,342.2 670.9 Cresta Reach – NFFR below Grizzly Creek Brown trout 0 0 0 0 0 1.6 Rainbow trout 267.8 139.5 242.8 129.1 211.4 204.0 Hardhead 44.6 1.6 1.6 177.9 104.9 0 Sac. pikeminnow 100.4 9.7 6.3 428.2 97.9 1.6 Sac. sucker 662.1 27.6 85.1 595.1 1,282.6 8.2 Smallmouth bass 0 0 6.3 15.7 1.8 4.9 Sculpin 3.7 418.5 823.0 440.8 417.6 762.2 All fish 1,078.7 596.9 1,165.2 1,786.8 2,116.1 982.5 Rock Creek Reach – NFFR at Indian Jim School Rainbow trout NS 1 60.6 40.8 72.7 NS NS Hardhead NS 342.3 261.0 213.2 NS NS Sac. pikeminnow NS 102.7 59.8 67.7 NS NS Sac. sucker NS 115.9 214.8 614.5 NS NS Smallmouth bass NS 0 5.4 10.0 NS NS Sculpin NS 371.2 413.2 163.0 NS NS All fish NS 992.6 995.0 1,141.1 NS NS Rock Creek Reach – NFFR below Granite Creek Rainbow trout 220.3 NS NS 135.5 242.1 116.7 Hardhead 153.3 NS NS 517.3 178.3 361.9 Sac. pikeminnow 483.7 NS NS 104.9 624.9 116.7 Sac. sucker 2,119.2 NS NS 80.1 1,109.2 26.59 Smallmouth bass 0 NS NS 0 0 1.5 Sculpin 334.1 NS NS 540.6 970.0 716.5 All fish 3,310.5 NS NS 1,378.4 3,124.5 1,339.9 Rock Creek Reach – NFFR at Rodgers Flat Brown trout 2.3 0 0 0 0 0 Rainbow trout 209.4 95.6 208.9 98.8 237.2 125.0 Hardhead 153.1 0 38.4 18.8 97.7 5.0 Sac. pikeminnow 168.9 46.4 14.4 11.8 79.1 2.5 Sac. sucker 864.8 17.4 31.2 18.8 600.0 7.5 Smallmouth bass 0 2.9 9.6 11.8 4.7 5.0 Sculpin 157.6 133.3 160.9 164.7 325.6 325.0 All fish 1,556.1 295.5 463.4 324.7 1,344.1 470.0 1 NS denotes no sampling

Table 15. Standardized biomass estimates (pounds per mile) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986. Species 1986 2002 2004 2005 2006 2010 Cresta Reach – NFFR below Bear Ranch Creek Brown trout 1.65 0 0 0 0 0 Rainbow trout 118.35 147.20 264.63 213.95 164.76 383.50 Hardhead 6.21 2.77 3.97 0 55.14 4.43 Sac. pikeminnow 6.49 9.62 12.68 0.05 0.43 10.05 Sac. sucker 1,415.50 3.14 19.88 26.16 1,444.60 2.34 Smallmouth bass 0.44 9.36 32.94 23.47 7.03 8.92 Sculpin 16.41 16.81 108.62 35.46 63.65 78.58 All fish 1,565.05 188.90 442.72 299.08 1,735.60 487.84 Cresta Reach – NFFR below Grizzly Creek Brown trout 0 0 0 0 0 0.89 Rainbow trout 192.39 229.44 307.18 116.96 100.72 192.24 Hardhead 0.61 0.06 0.05 3.34 1.13 0 Sac. pikeminnow 2.29 1.35 0.99 12.12 48.46 0.64 Sac. sucker 33.95 90.34 158.21 37.90 1,891.95 11.48 Smallmouth bass 0 0 2.34 4.91 2.57 0.54 Sculpin 1.68 89.97 135.21 116.86 59.38 136.96 All fish 230.92 411.16 603.98 292.09 2,104.21 342.75 Rock Creek Reach – NFFR at Indian Jim School Rainbow trout NS 1 214.59 166.69 327.89 NS NS Hardhead NS 252.72 70.43 967.38 NS NS Sac. pikeminnow NS 49.98 18.42 49.30 NS NS Sac. sucker NS 1,254.24 2,124.67 6,663.07 NS NS Smallmouth bass NS 0 1.13 1.28 NS NS Sculpin NS 50.13 22.01 17.25 NS NS All fish NS 1,821.66 2,403.35 8,026.17 NS NS Rock Creek Reach – NFFR below Granite Creek Rainbow trout 111.90 NS NS 285.11 178.38 174.58 Hardhead 8.44 NS NS 111.40 8.88 83.56 Sac. pikeminnow 19.24 NS NS 24.43 71.41 55.56 Sac. sucker 1,216.91 NS NS 109.92 108.95 24.41 Smallmouth bass 0 NS NS 0 0 0.08 Sculpin 40.75 NS NS 118.46 121.48 120.59 All fish 1,397.25 NS NS 649.32 489.10 458.78 Rock Creek Reach – NFFR at Rodgers Flat Brown trout 40.88 0 0 0 0 0 Rainbow trout 118.16 300.73 492.26 228.03 216.76 420.37 Hardhead 3.86 0 11.78 3.89 35.07 0.53 Sac. pikeminnow 43.86 23.11 6.47 21.63 73.79 2.67 Sac. sucker 1,682.54 147.62 61.02 24.28 123.14 36.60 Smallmouth bass 0 0.80 4.07 2.30 4.89 2.66 Sculpin 39.90 34.04 33.16 40.06 45.13 79.91 All fish 1,929.20 506.30 608.76 320.18 498.80 542.74 1 NS denotes no sampling

Table 16. Standardized biomass estimates (pounds per acre) for fish species at the five Rock Creek-Cresta shallow-water study sites sampled by electrofishing since 1986. Species 1986 2002 2004 2005 2006 2010 Cresta Reach - NFFR below Bear Ranch Creek Brown trout 0.26 0 0 0 0 0 Rainbow trout 18.60 16.25 29.21 24.45 19.22 42.86 Hardhead 0.98 0.31 0.44 0 6.43 0.50 Sac. Pikeminnow 1.02 1.06 1.40 0.01 0.05 1.12 Sac. Sucker 222.47 0.35 2.19 2.99 168.51 0.26 Smallmouth bass 0.07 1.03 3.64 2.68 0.82 1.00 Sculpin 2.58 1.86 11.99 4.05 7.43 8.78 All fish 245.98 20.86 48.87 34.18 202.45 54.51 Cresta Reach – NFFR below Grizzly Creek Brown trout 0 0 0 0 0 0.09 Rainbow trout 20.68 20.81 27.52 10.57 10.13 19.01 Hardhead 0.07 0.01 0.01 0.30 0.11 0 Sac. Pikeminnow 0.25 0.12 0.09 1.10 4.88 0.06 Sac. Sucker 3.65 8.20 14.17 3.42 190.35 1.14 Smallmouth bass 0 0 0.21 0.44 0.26 0.05 Sculpin 0.18 8.16 12.11 10.56 5.97 13.55 All fish 24.82 37.30 54.11 26.39 211.70 33.90 Rock Creek Reach - NFFR at Indian Jim School Rainbow trout NS 1 31.95 25.23 47.97 NS NS Hardhead NS 37.62 10.66 141.53 NS NS Sac. Pikeminnow NS 7.44 2.79 7.21 NS NS Sac. Sucker NS 186.72 321.62 974.81 NS NS Smallmouth bass NS 0 0.17 0.19 NS NS Sculpin NS 7.46 3.33 2.52 NS NS All fish NS 271.19 363.80 1,174.23 NS NS Rock Creek Reach – NFFR below Granite Creek Rainbow trout 9.24 NS NS 27.70 16.65 17.49 Hardhead 0.70 NS NS 10.82 0.83 8.37 Sac. Pikeminnow 1.59 NS NS 2.37 6.67 5.56 Sac. Sucker 100.50 NS NS 10.68 10.17 2.45 Smallmouth bass 0 NS NS 0 0 0.01 Sculpin 3.37 NS NS 11.51 11.34 12.08 All fish 115.39 NS NS 63.08 45.66 45.95 Rock Creek Reach – NFFR at Rodgers Flat Brown trout 3.95 0 0 0 0 0 Rainbow trout 11.41 34.65 51.71 23.47 21.86 46.77 Hardhead 0.37 0 1.24 0.40 3.54 0.06 Sac. Pikeminnow 4.24 2.66 0.68 2.23 7.44 0.30 Sac. Sucker 162.46 17.01 6.41 2.50 12.42 4.07 Smallmouth bass 0 0.09 0.43 0.24 0.49 0.30 Sculpin 3.85 3.92 3.48 4.12 4.55 8.89 All fish 186.28 58.33 63.95 32.95 50.31 60.39 1 NS denotes no sampling

One of the most noteworthy results of the 2010 shallow-water electrofishing surveys was the capture of very few Sacramento suckers in the Project area. In 2006 suckers dominated the fish populations of the Project area, especially in the Cresta Reach. In 2006, over 2,500 suckers were captured during the shallow-water electrofishing surveys (1,660 in the Cresta Reach and 854 in the Rock Creek Reach). In 2010, only 32 suckers were captured at the four sites (11 in the Cresta Reach and 21 in the Rock Creek Reach [Table 6]). The 2010 abundance estimates for suckers were the lowest on record for the four survey sites and were less than 3 percent of the 2006 levels at all four survey sites (tables 13 and 14). The biomass estimates for suckers in 2010 were the lowest on record for all sites (Tables 15 and 16), except for Rodgers Flat in 2005.

The large decrease in sucker abundance and biomass noted between the 2006 and 2010 surveys was due largely to the lack of sucker fry in 2010. In 2006, 2,417 suckers less than 100 mm in length were captured during the surveys, while in 2010 only 14 suckers less than 100 mm in length were captured at the four shallow-water electrofishing sites. This represents a decline of over 99 percent between these two survey periods. Preliminary results from the 2010 dive survey results (Allen and Gast 2011) confirm the observed decline in sucker fry in the Project area noted in the shallow-water electrofishing survey over the same period. The 2006 dive surveys counted 1,031.3 sucker fry per 1,000 feet of fry lane surveyed in both the Rock Creek and Cresta reaches of the NFFR, while the preliminary 2010 survey count for small suckers were only 3.1 fish per 1,000 feet of fry lane surveyed, also a 99 percent decline in sucker fry abundance between the two survey periods (Allen and Gast 2011). This similar magnitude decline in sucker fry abundance between the 2006 and 2010 noted in both the dive count and shallow-water electrofishing surveys suggests that the decline in sucker fry abundance and biomass noted in the shallow- water electrofishing results is likely real and not a function of electrofishing sampling error or capture inefficiency.

45 Cresta Reach of the North Fork Feather River Rainbow trout

40 CDFG 1986 data (2 shallow-water sites plus pool; n = 183) ECORP 2002 data (2 shallow-water sites only; n = 103) 35 TRPA 2004 data (2 shallow-water sites only; n = 228) TRPA 2005 data (2 shallow-water sites only; n = 110) TRPA 2006 data (2 shallow-water sites only; n = 236) 30 TRPA 2010 data (2 shallow-water sites; n = 177)

20 Number Number of Fish

0 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 365 385 405 425 Fork Length (mm)

Figure 15. Length-frequency data for rainbow trout captured during six separate late-fall electrofishing surveys in the Cresta Reach of the NFFR. Note that the 1986 data includes data from two shallow-water and one pool sites, the 2002-2010 data includes data from two shallow-water sites only.

Rock Creek Reach of the North Fork Feather River

60 Rainbow trout

CDFG 1986 data (2 shallow-water sites plus pool; n = 305) ECORP 2002 data (2 shallow-water sites only; n = 47) 50 TRPA 2004 data (2 shallow-water sites only; n = 100) TRPA 2005 data (3 shallow-water sites; n = 151) TRPA 2006 data (2 shallow-water sites; n = 232) TRPA 2010 data (2 shallow-water sites; n = 119) 40

30 Number Number of Fish

0 35 55 75 95 115 135 155 175 195 215 235 255 275 295 315 335 355 375 395 Fork Length (mm)

Figure 16. Length-frequency data for rainbow trout captured during six separate late-fall electrofishing surveys in the Rock Creek Reach of the NFFR. Note that the 1986 data includes data from two shallow-water and one pool sites, the 2002, 2004, 2006, and 2010 data includes data from two shallow-water sites only, and the 2005 data includes data from three shallow-water sites.

At this time it is unknown what is responsible for the very low numbers of the 2010 cohort of Sacramento suckers. It may have been poor spawning success during the spring period for this species or perhaps there was an event that essentially limited the survival of young- of-the-year sucker during the summer period. The available evidence does not suggest that a lack of large spawners was responsible for the poor 2010 year class. Large suckers (>16 inches in length) were found in the deep water areas throughout the Project area during the 2010 dive count surveys (Allen and Gast 2011).

The results of the 2010 shallow-water electrofishing also show a similar level of decline in minnow fry production. In 2006, 190 hardhead fry less than 70 mm in length were captured during the shallow-water electrofishing surveys (75 in the Cresta Reach and 115 in the Rock Creek Reach). In 2010, a total of only 17 hardhead fry were captured at the four sites (2 in the Cresta Reach and 15 in the Rock Creek Reach). A similar decline in pikeminnow fry production was noted. In 2006, 247 pikeminnow fry less than 70 mm in length were captured during the shallow-water electrofishing surveys (40 in the Cresta Reach and 207 in the Rock Creek Reach). In 2010, a total of only 9 pikeminnow fry were captured at the four sites (all in the Rock Creek Reach). This poor production of the 2010 cohort of minnows that was noted in the shallow-water electrofishing data was also noted in the 2010 dive count results. The snorkel surveyors could not positively identify minnows less than 5 inches as either hardhead or pikeminnow, so they were lumped into a combined “hardhead/pikeminnow fry” category. The 2006 dive surveys counted 3,159.1 hardhead/pikeminnow fry per 1,000 feet of fry lane surveyed in both the Rock Creek and Cresta reaches of the NFFR, while the preliminary 2010 survey counts for the combined minnow fry category were only 700.1 fish per 1,000 feet of fry lane surveyed, a decline of about 78 percent between the two survey periods (Allen and Gast 2011).

Again, the relatively low abundance of minnow fry noted in 2010 dive count survey results suggest that the low abundance and biomass estimates for both hardhead and pikeminnow

fry derived from the shallow-water electrofishing surveys are most likely real and not due to poor sampling efficiency. As was already discussed above, it is not known what was responsible for the poor production of the 2010 cohort for both hardhead and pikeminnow. It may have been poor spawning success during the spring period for this species or perhaps there was an event that limited the over-summer survival of the fry age class. The available evidence does not suggest a lack of large spawners was responsible for the poor year class. Large hardhead and pikeminnow (>16 inches in length) were observed in the deep water areas throughout the Project area during the 2010 dive count surveys (Allen and Gast 2011).

The 2010 data did not suggest any dramatic changes in the smallmouth bass populations at the four electrofishing sites compared to 2006 (Table 11). Comparison of the 1986-2010 survey data for smallmouth bass indicates that this introduced centrarchid continues to be only a minor component of the Rock Creek-Cresta shallow-water fish populations either in terms of abundance, or biomass (Tables 13 through 16). One notable difference in the 2010 smallmouth bass data compared to 2006 was the larger number of small sized bass in the most recent population survey. This is shown by the decrease in the mean weight of smallmouth bass at the three sites where they present in both years (Table 11).

The 2010 electrofishing surveys continue to show that sculpin are a large proportion of the fish populations at all the sites. A comparison of the 2006 to 2010 abundance indices show mixed trends, with a an increase at one site (Grizzly), a decrease at two sites (Bear Ranch and Granite) and no change at one site (Rodgers Flat) over this four year interval (Tables 13 and 14). However, the biomass indices generally indicate increases in the sculpin production in three of the four sites, with no change at the Granite Creek Site over this four year interval (Tables 15 and 16).

One assumed benefit to raising the base flow in the Project area, as outlined in the Rock Creek Cresta SA, has been that the trout populations in the NFFR would also increase in

response to improved habitat conditions. The results of the October 2010 surveys indicate that in terms of abundance, the rainbow trout populations in the Rock Creek–Cresta Project area have not exhibited an increase in numbers in response to the latest increases in Project base flows that have occurred during the past two years. It should be noted that the base flows during 2007 and 2008 , which were classified as “critically dry” (Figure 1), were generally less than or equal to the flows during the first 5-year flow study period and flows in 2009, which was classified as “dry”, were intermediate between 2007/2008 and 2010 flows. Since higher base flows relative to the first 5-year study period have only been occurring during the past two years, it may be that the trout populations may not have yet responded to new habitat conditions provided by the new flow regime. In terms of biomass, the 2010 rainbow trout populations have shown increases over those measured in 2006 at three of the four sites (Bear Ranch, Grizzly, and Rodgers Flat), with the fourth site (Granite) showing no change.

As was discussed earlier, this apparent discrepancy (i.e., generally lower abundance levels coupled with generally higher biomass) appears to be due to reduced spawning success/survival of the 2010 cohort and better survival of the 2008 and 2009 cohorts in the most recent surveys (Table 12). It should also be reiterated that the poor young-of-the-year age class for trout was also evident for the other native fishes as well, especially for the minnow and suckers. There is no obvious explanation for the greatly reduced 2010 cohorts of trout, minnow and sucker fry. All these native fishes are spring spawners, likely spawning in the period of March through late May (Moyle 2002). CDFG (1988) estimated that the peak spawning period for rainbow trout in the NFFR and its tributaries was mid- April. Examination of the hydrograph for the past few years (Figure 17) does not show any particular event that would explain the observed abundances for the native fish species (i.e., poor spawning in 2010 compared to 2008 or 2009). This search for an explanation for the low numbers in the 2010 cohort of native fishes is further complicated by the fact that trout population levels observed in the NFFR may not be solely controlled by the rearing

conditions in the mainstem NFFR, but instead may be a function of the spawning success and juvenile recruitment from the tributaries (CDFG 1988).

The complete shallow-water electrofishing data record (1986-2010) suggests that there is substantial annual variation in the NFFR trout populations and age cohorts both at individual sites as well as at all sites combined (Tables 11 through 13) Additional surveys over the next two years may help clarify the trout population responses to the new flow regime.

Conclusions

Despite the increases in the base flow levels since 2002, the numbers and biomass of rainbow trout in the Project area have been highly variable between sampling efforts and sites. This variability has resulted in meeting some of the seven ERC-defined goals (see the Introduction section) for providing “an excellent trout fishery and functioning ecosystem to all naturally occurring species” in some years, at some sites, although not at all sites in any year sampled to date. The results of the shallow-water electrofishing surveys can be used to evaluate the achievement of four of these performance criteria: 1) A. Wild rainbow trout population with 4 age classes; 2) D. Adult rainbow trout available for catch > 17 inches; 3) E. Harvestable component of 595 lbs/mile wild trout; and 4) F. Wild trout biomass of 62 lbs/acre (catch). The other three criteria are specific to the Angler Creel Survey Study (Meadowbrook Conservation Service 2010), and are discussed there. The status for achieving each of these four criteria listed above in 2010, as well as the status of the affected river reaches in the Project area being a “functioning ecosystem to all naturally occurring species”, are presented below.

12000

11000 NFFR - Cresta Reach Gage NF-56 10000 WY 2007 9000 WY2008 8000 WY 2009

7000 WY 2010

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18-Mar

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12-Nov 26-Nov

10-Dec 24-Dec 19-Aug 16-Sep 30-Sep

13-May 27-May Date

10000

9000 NFFR - Rock Creek Reach Gage NF-57 8000 WY 2007

7000 WY 2008 WY 2009 6000 WY 2010

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1-Apr

1-Oct

7-Jan

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5-Aug 2-Sep

22-Jul

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18-Mar

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12-Nov 26-Nov

10-Dec 24-Dec 19-Aug 16-Sep 30-Sep

13-May 27-May Date Figure 17. Mean daily stream flow records for the Cresta (top) and Rock Creek (bottom) study reaches during the 2007-2010 water years. (Data from USGS and PG&E).

Criteria A. Wild rainbow trout population with 4 age classes

The 2010 data indirectly confirms the achievement of a wild rainbow trout population with 4 age classes. The 2010 length-frequency data evaluated using the ECORP (2003) age- length relationships indicates the presence of five age classes of rainbow trout at Bear Ranch Creek, Granite Creek, and Rodgers Flat sites , and four age classes at the Grizzly Creek Site (Table 16).

Criteria D. Adult rainbow trout available for catch > 17 inches

The 2010 shallow-water electrofishing survey did not include the capture of any of rainbow trout greater than 17 inches (432 mm) in length. The largest rainbow trout from our survey was 424 mm FL (16.7 inch) in length captured at the Bear Ranch Creek site. Despite this lack of evidence from the shallow-water surveys, observations made during concurrent angler creel reaches (Meadowbrook Conservation Services 2010) and dive count surveys reaches (Allen and Gast 2011) both indicate the presence of large trout greater than 17 inches in both the Cresta and Rock Creek reaches.

Criteria E. Harvestable component of 595 lbs/mile wild trout

While the harvestable component criteria addresses all wild trout, in fact all but one of the 1,494 trout captured in the five shallow-water surveys conducted since 2002 have been rainbow trout (99.93%of all trout). Based on these recent survey results, this ERC-defined goal applies almost exclusively to rainbow trout. The 2010 biomass estimates for all sizes of wild trout captured (which included one brown trout) ranged from 175 to 420 pounds per mile (Table 15), indicating that the SA criteria of a wild trout population possessing a harvestable component of 595 pounds per mile was not met. In fact, over the recent survey period (1986-2010), none of the combined rainbow and brown trout biomass estimates have ever approached this 595 pound per mile criteria. Given the fact that the electrofishing surveys are concentrated in shallow water habitats where juvenile fish tend to

reside and that the larger harvestable adult trout tend to reside in the deeper-water habitats, it appears unlikely that the electrofishing surveys will ever document biomass levels that meet this criteria.

The SA does not specify how the “harvestable component” for the wild trout criteria should be defined. In fact, the Rock Creek and Cresta reaches are now managed under catch and release regulations and no harvest (i.e., keeping of catch) of any trout is allowable. However, for this exercise we assumed that all trout eight inches or greater in length would be considered “harvestable”. Based upon the Project area-wide dive count data, we determined an average size for rainbow trout in each of the habitat-specific size class categories (Allen and Gast 2011). Given the extremely rare frequency that brown trout were observed during the dive counts (a total of two brown trout in the four years of surveys since 2004) no abundance estimates from the dive count data have been made for this species. Mean weights for the snorkel count rainbow trout abundance estimates were then derived by back-calculation using the mean condition factors for rainbow in those size categories collected from each of the shallow-water electrofishing surveys (2004 – 2010). Based upon the dive count density estimates and the electrofishing length-weight relationships, we were able to estimate habitat-specific rainbow trout biomass estimates in both the Rock Creek and Cresta reaches for comparison to the SA criteria (Table 17).

These biomass estimates demonstrate that even when the abundance estimates derived across all shallow and deep water areas in the Project area are included, the SA “harvestable” component for wild trout biomass criteria (595 pounds per mile) have rarely ever been approached. Except for the Rock Creek shallow pool biomass estimates for 2005 (569 pounds per mile) none of the other biomass estimates for wild rainbow trout greater than or equal to eight inches have ever even exceeded 325 pounds per mile, and have rarely even exceeded 250 pounds per mile.

Table 17. Biomass estimates for wild rainbow trout ≥ 8 inches in length for each of the habitats in the Cresta and Rock Creek reaches of the Project area for 2004 through 2010 are based on the dive count abundance estimates and shallow- water electrofishing length-weight relationships for that particular year.

Wild rainbow trout ≥8 inches biomass estimate (pounds/mile) Habitat Type Cresta Reach Rock Creek Reach 2004 Riffle 76.1 133.0 Run 307.1 235.1 Shallow Pool 28.1 568.7 Deep Pool 130.0 157.3 2005 Riffle 111.1 162.8 Run 224.3 255.8 Shallow Pool 89.4 321.7 Deep Pool 83.2 85.4 2006 Riffle 78.7 74.6 Run 131.7 99.0 Shallow Pool 45.7 167.2 Deep Pool 31.4 45.3 2010 Riffle 111.7 60.1 Run 154.2 83.1 Shallow Pool 57.0 83.7 Deep Pool 21.1 112.2

Criteria F. Wild trout biomass 62 lbs/acre (catch)

The 2010 biomass estimates for all trout captured (including only one brown trout) again ranged from about 17 to 47 pounds per acre (Table 16), indicating that the SA criteria of a wild trout population possessing a harvestable component of 62 pounds per acre was not met. In fact, over the recent survey period (1986-2010), the highest biomass estimate for wild trout was for Rodgers Flat in 2004, when 52 pounds per acre was measured. Because the electrofishing surveys are concentrated in shallow water habitats where juvenile fish tend to reside and that the larger harvestable adult trout tend to reside in the deeper-water

habitats, it appears unlikely that the electrofishing surveys will ever document biomass levels that meet this criteria.

Trout condition factor

Although not a specified monitoring criteria, condition factor for both rainbow and brown trout were calculated in 2010 (Figure 6). The calculated condition factors for the 2010 length-weight data suggests the presence of healthy rainbow and brown trout populations at all sites (i.e., average condition factors for all sites ≥1.20).

Functional ecosystem to all naturally occurring species

In addition to providing “an excellent trout fishery”, the SA also has an objective of providing a “functioning ecosystem to all naturally occurring species”. We understand this to infer some commitment to maintain healthy populations of non-trout native fish species in the Project area. One of the most noteworthy results of the 2010 shallow-water electrofishing surveys was the documentation of very low numbers of Sacramento sucker in the Project area. The 2010 electrofishing data also indicated poor production of the 2010 cohort for both pikeminnow and hardhead minnow species. The declines in abundance for these three native non-game species relative to the other recent sampling efforts may be a function of annual variations in the populations or could be a response to some other abiotic or biotic factor.

Continued sampling in future years should provide additional data for evaluating the abundance and biomass of the resident fish populations in the Project area and for assessing the wild rainbow trout population status at the various base flow scenarios relative to the goals specified in the Settlement Agreement.

Recommendations

To date, none of the rainbow trout scale samples (n=1,275) collected since 2002 have been examined. We are recommending that the scales collected in the 2004 through 2006 and for those collected during the next series of surveys (2010-2013) be examined for age- length analysis. CDFG (1988) suggested that mean length of rainbow trout at annulus II formation was significantly greater for years with higher minimum flows in the Rock Creek and Cresta reaches. Comparison of the age-length data collected since the 1986 surveys may be helpful in determining potential benefits of raising the base flows in the Project area. The 2004-2006 and 2010 scale samples are archived and can be easily accessed for this recommended analysis.

Literature Cited

Allen, M. and T. Gast. 2006. Use of dive counts to estimate fish population abundance in the Rock Creek-Cresta reaches of the North Fork Feather River, California – 2005 Final Report. March 28, 2006 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Allen, M., and T. Gast. 2007. Use of dive counts to estimate fish population abundance in the Rock Creek-Cresta reaches of the North Fork Feather River, California – 2006 Final Report. May 31, 2007 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Allen, M., and T. Gast. 2011. Use of dive counts to estimate fish population abundance in the Rock Creek-Cresta reaches of the North Fork Feather River, California – 2010 Draft Report. February 17, 2011 draft report prepared for by Thomas R. Payne & Associates for Technical and Scientific Support, Pacific Gas and Electric Company, San Ramon, CA.

Allen, M., and S. Riley. 2006. Use of dive counts to estimate fish population abundance in the Rock Creek-Cresta reaches of the North Fork Feather River, California - 2004 Final Report. February 11, 2005 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Bagenal, T.B., and F.W. Tesch. 1978. Age and growth. Chapter 5 in T.B. Bagenal, editor. Methods for assessment of fish production in fresh waters, 3rd edition. International Biological Programme Handbook 3. Blackwell Scientific Publications, Oxford. 365p.

California Department of Fish and Game. 1988. Rock Creek–Cresta Project (FERC 1962) fisheries management study, North Fork Feather River, California. 1 July 1988 final report prepared by Region 2 Environmental Services and submitted to Pacific Gas and Electric Company.

DeVries, D.R., and R.V. Frie. 1996. Determination of age and growth. Chapter 16 in B.R. Murphy and D.W. Willis, editors. Fisheries Techniques, 2nd edition. American Fisheries Society, Bethesda, MD. 732p.

ECORP Consulting, Inc. 2003. Draft results of backpack electrofishing surveys for the Rock Creek-Cresta Project (FERC No. 1962), Plumas County, California. 4 March 2003 draft report prepared for Pacific Gas and Electric Company.

Everhart, H.W., A.W. Eipper, and W.D. Youngs. 1975. Principles of fishery science. Cornell University Press, Ithaca, NY. 288p.

Flint, R.A. 1980. Chemical treatment of the North Fork Feather River, Butte and Plumas counties, California, 1977. California Department of Fish and Game, Inland Fisheries Administrative Report No. 80-4.

Garcia and Associates. 2003. 2002 angler creel survey: Rock Creek-Cresta Project (FERC No. 1962) North Fork Feather River, Butte and Plumas counties, California. March 2003 draft report prepared for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Meadowbrook Conservation Services. 2005. 2004 angler creel survey: Rock Creek-Cresta Project (FERC No. 1962) North Fork Feather River, Butte and Plumas counties, California. March 2005 draft report prepared for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Meadowbrook Conservation Services. 2006. 2005 angler creel survey: Rock Creek-Cresta Project (FERC No. 1962) North Fork Feather River, Butte and Plumas counties, California. March 2006 final report prepared for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Meadowbrook Conservation Services. 2010. 2010 angler creel survey: Rock Creek-Cresta Project (FERC No. 1962) North Fork Feather River, Butte and Plumas counties, California. Executive Summary. December 2010 draft report prepared for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Moyle, P.B. 2002. Inland Fishes of California, 2nd edition. University of California Press, Berkeley, California. 502p.

Moyle, P.B., B. Vondracek, and G.D. Grossman. 1983. Responses of fish populations in the North Fork of the Feather River, California, to treatments with fish toxicants. North American Journal of Fisheries Management 3:48-60.

Salamunovich, T. 2004a. Rock Creek-Cresta (FERC No. 1962) Recreation and pulse flow biological evaluation: stranding and displacement studies, year 1 – 2002. October 5, 2004 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2004b. Rock Creek-Cresta (FERC No. 1962) Recreation and pulse flow biological evaluation: stranding and displacement studies, year 2 – 2003. December 2004 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2005. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – November 2004. January 7, 2005 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2006. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – October 2005. November 17, 2006 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2007a. Bucks Creek Project (FERC No. 619) 2006 fish population final report for Bucks and Grizzly creeks. April 2007 final report prepared by Thomas R. Payne & Associates for Environmental Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2007b. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – October 2006. February 8, 2007 draft report prepared by Thomas R. Payne & Associates for Technical Project Support, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2009. Bucks Creek Project (FERC No. 619) 2009 fish population final report for Bucks and Grizzly creeks. December 2009 final report prepared by Thomas R. Payne & Associates for Land and Environmental Management Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. and A. Berg, contributors. 2002a. Bucks Creek Project 2002 fish population report, FERC Project No. 619, Article 103. December 2002 report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. and A. Berg, contributors. 2002b. Grizzly Creek 2002 fish population report, Grizzly Creek Rehabilitation Monitoring Program, FERC Project No. 619, Article 404(c). December 2002 report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Van Deventer, J.S., and W.S. Platts. 1989. Microcomputer software system for generating population statistics from electrofishing data - user's guide for MicroFish 3.0. USDA, Forest Service General Technical Report INT-254. Intermountain Research Station, Ogden, Utah. 29p.

White, G.C., K.P. Burnham, D.L. Otis, and D.R. Anderson. 1978. User's manual for program CAPTURE. Utah State University Press, Logan, Utah. 40p.

White, G.C., D.R. Anderson, K.P. Burnham, and D.L. Otis. 1982. Capture-recapture and removal methods for sampling closed populations. LA-8787-NERP. Los Alamos National Laboratory, Los Alamos, New Mexico. 235p.

Appendix A

Rock Creek-Cresta Relicensing Settlement Agreement Minimum Flow Schedules

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Appendix A. Summary of Rock Creek-Cresta Project minimum flow schedules for three consecutive five-year periods under various water year types as specified in the Rock Creek Cresta Relicensing Settlement Agreement. Water year types to be determined by California Department of Water Resources forecasts of unimpaired flow of North Fork Feather River into Lake Oroville.

1st 5-year Period Cresta Rock Creek Normal/Wet Dry Crit. Dry Normal/Wet Dry Crit. Dry Oct 220 175 140 180 150 150 Nov 220 175 100 180 150 110 Dec 240 190 100 200 160 110 Jan 240 190 100 225 180 110 Feb 240 190 100 225 180 110 Mar 250 200 100 250 200 110 Apr 250 200 100 250 200 110 May 250 200 140 250 200 150 June 240 190 140 220 175 150 Jul 220 175 140 180 150 150 Aug 220 175 140 180 150 150 Sep 220 175 140 180 150 150

2nd 5-year Period Cresta Rock Normal/Wet Dry Crit. Dry Normal/Wet Dry Crit. Dry Oct 325 260 140 260 210 150 Nov 325 260 100 260 210 110 Dec 350 280 100 350 280 110 Jan 350 280 100 350 280 110 Feb 350 280 100 350 280 110 Mar 350 280 100 350 280 110 Apr 350 280 100 350 280 110 May 350 280 140 350 280 150 June 325 260 140 260 210 150 Jul 325 260 140 260 210 150 Aug 325 260 140 260 210 150 Sep 325 260 140 260 210 150

3rd 5-year Period Cresta Rock Normal/Wet Dry Crit. Dry Normal/Wet Dry Crit. Dry Oct 325 260 140 260 210 150 Nov 325 260 100 260 210 110 Dec 350 280 100 350 280 110 Jan 350 280 100 350 280 110 Feb 350 280 100 350 280 110 Mar 350 280 100 350 280 150 Apr 350 280 100 350 280 150 May 350 280 140 350 280 150 June 325 260 140 600 480 150 Jul 325 260 140 260 210 150 Aug 325 260 140 260 210 150 Sep 325 260 140 260 210 150

Appendix B

October 2010 Rock Creek-Cresta Shallow-water Electrofishing Site Habitat Characteristic Data Sheets

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Appendix C

October 2010 Rock Creek-Cresta Shallow-water Electrofishing Data Sheets

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Appendix D

MicroFish 3.0 and Program CAPTURE Output for the October 2010 Rock Creek-Cresta Shallow-water Electrofishing Data

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Stream: NFFR below Bear Ranch Creek, 19 October 2010 Species: Rainbow trout

Removal Pattern: 29 27 10 7 Total Catch = 73 Population Estimate = 83

Chi Square = 3.384 Pop Est Standard Err = 6.620 Lower Conf Interval = 73.000 Upper Conf Interval = 96.167

Capture Probability = 0.403 Capt Prob Standard Err = 0.070 Lower Conf Interval = 0.265 Upper Conf Interval = 0.542

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 69.83317 .

______

Stream: NFFR below Bear Creek, 19 October 2010 Species: Hardhead

Removal Pattern: 1 2 0 0 Total Catch = 3 Population Estimate = 3

Chi Square = 3.036 Pop Est Standard Err = 0.359 Lower Conf Interval = 3.000 Upper Conf Interval = 4.545

Capture Probability = 0.600 Capt Prob Standard Err = 0.284 Lower Conf Interval = -.621 Upper Conf Interval = 1.821

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 1.455452 .

Stream: NFFR below Bear Creek, 19 October 2010 Species: Sacramento pikeminnow

Removal Pattern: 2 0 0 0 Total Catch = 2 Population Estimate = 2 (Using Program CAPTURE)

Chi Square = 0.001 Pop Est Standard Err = 0.000 Lower Conf Interval = 2.000 Upper Conf Interval = 3.000

Capture Probability = 0.999675

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 1.00.

______

Stream: NFFR below Bear Ranch Creek, 19 October 2010 Species: Sacramento sucker

Removal Pattern: 4 1 0 1 Total Catch = 6 Population Estimate = 6

Chi Square = 3.330 Pop Est Standard Err = 0.508 Lower Conf Interval = 6.000 Upper Conf Interval = 7.305

Capture Probability = 0.600 Capt Prob Standard Err = 0.201 Lower Conf Interval = 0.084 Upper Conf Interval = 1.116

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 4.69489 .

______

Stream: NFFR below Bear Ranch Creek, 19 October 2010 Species: Smallmouth bass

Removal Pattern: 9 3 4 2 Total Catch = 18 Population Estimate = 19

Chi Square = 1.781 Pop Est Standard Err = 2.184 Lower Conf Interval = 18.000 Upper Conf Interval = 23.588

Capture Probability = 0.462 Capt Prob Standard Err = 0.134 Lower Conf Interval = 0.179 Upper Conf Interval = 0.744

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 14.41228 .

______

Stream: NFFR below Bear Ranch Creek, 19 October 2010 Species: Riffle sculpin

Removal Pattern: 77 64 31 33 Total Catch = 205 Population Estimate = 275

Chi Square = 3.855 Pop Est Standard Err = 26.663 Lower Conf Interval = 222.474 Upper Conf Interval = 327.526

Capture Probability = 0.289 Capt Prob Standard Err = 0.047 Lower Conf Interval = 0.197 Upper Conf Interval = 0.381

______

Stream: NFFR below Bear Ranch Creek, 19 October 2010 Species: Prickly sculpin

Removal Pattern: 4 3 4 3 Total Catch = 14 Population Estimate = 27

Chi Square = 0.509 Pop Est Standard Err = 26.016 Lower Conf Interval = 14.000 Upper Conf Interval = 80.488

Capture Probability = 0.163 Capt Prob Standard Err = 0.205 Lower Conf Interval = -.258 Upper Conf Interval = 0.584

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -26.48788 .

______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Rainbow trout

Removal Pattern: 55 31 18 Total Catch = 104 Population Estimate = 125

Chi Square = 0.050 Pop Est Standard Err = 11.353 Lower Conf Interval = 104.000 Upper Conf Interval = 147.480

Capture Probability = 0.444 Capt Prob Standard Err = 0.073 Lower Conf Interval = 0.301 Upper Conf Interval = 0.588

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 102.5203 .

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Brown trout

Removal Pattern: 1 0 0 Total Catch = 1 Population Estimate = 1 (Using Program CAPTURE)

Chi Square = 0.000 Pop Est Standard Err = 0.00014 Lower Conf Interval = 1.000 Upper Conf Interval = 2.000

Capture Probability = 0.999555

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 0.00. ______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Hardhead

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0 ______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Sacramento pikeminnow

Removal Pattern: 1 0 0 Total Catch = 1 Population Estimate = 1 (Using Program CAPTURE)

Chi Square = 0.000 Pop Est Standard Err = 0.00014 Lower Conf Interval = 1.000 Upper Conf Interval = 2.000

Capture Probability = 0.999555

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 0.00. ______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Sacramento sucker

Removal Pattern: 2 3 0 Total Catch = 5 Population Estimate = 5

Chi Square = 3.711 Pop Est Standard Err = 0.787 Lower Conf Interval = 5.000 Upper Conf Interval = 7.186

Capture Probability = 0.625 Capt Prob Standard Err = 0.262 Lower Conf Interval = -.104 Upper Conf Interval = 1.354

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 2.814384 .

______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Smallmouth bass

Removal Pattern: 1 1 1 Total Catch = 3 Population Estimate = 3

Chi Square = 1.345 Pop Est Standard Err = 1.271 Lower Conf Interval = 3.000 Upper Conf Interval = 8.469

Capture Probability = 0.500 Capt Prob Standard Err = 0.424 Lower Conf Interval = -1.323 Upper Conf Interval = 2.323

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -2.469018 .

______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Riffle sculpin

Removal Pattern: 145 80 68 Total Catch = 293 Population Estimate = 412

Chi Square = 2.645 Pop Est Standard Err = 39.798 Lower Conf Interval = 333.597 Upper Conf Interval = 490.403

Capture Probability = 0.338 Capt Prob Standard Err = 0.049 Lower Conf Interval = 0.241 Upper Conf Interval = 0.436

______

Stream: NFFR below Grizzly Creek, 20 October 2010 Species: Prickly sculpin

Removal Pattern: 17 12 9 Total Catch = 38 Population Estimate = 55

Chi Square = 0.113 Pop Est Standard Err = 16.518 Lower Conf Interval = 38.000 Upper Conf Interval = 88.118

Capture Probability = 0.319 Capt Prob Standard Err = 0.141 Lower Conf Interval = 0.037 Upper Conf Interval = 0.602

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 21.88232 .

______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Rainbow trout

Removal Pattern: 19 27 11 8 4 Total Catch = 69 Population Estimate = 79

Chi Square = 7.459 Pop Est Standard Err = 6.713 Lower Conf Interval = 69.000 Upper Conf Interval = 92.365

Capture Probability = 0.332 Capt Prob Standard Err = 0.063 Lower Conf Interval = 0.206 Upper Conf Interval = 0.457

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 65.63531 . ______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Hardhead

Removal Pattern: 12 1 14 4 18 Total Catch = 49 Population Estimate = 245

Chi Square = 22.871 Pop Est Standard Err = 510.264 Lower Conf Interval = 49.000 Upper Conf Interval = 1,250.220

Capture Probability = 0.043 Capt Prob Standard Err = 0.098 Lower Conf Interval = -.149 Upper Conf Interval = 0.235

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -760.2197 .

WARNING: Run terminated at population estimate equal to 5 times the total catch. Cause: irregular or non-descending removal pattern. Results should not be considered reliable. ______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Sacramento pikeminnow

Removal Pattern: 10 11 8 5 8 Total Catch = 42 Population Estimate = 79

Chi Square = 1.558 Pop Est Standard Err = 40.059 Lower Conf Interval = 42.000 Upper Conf Interval = 158.758

Capture Probability = 0.140 Capt Prob Standard Err = 0.096 Lower Conf Interval = -.051 Upper Conf Interval = 0.330

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -0.7575226 .

______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Sacramento sucker

Removal Pattern: 12 0 4 0 2 Total Catch = 18 Population Estimate = 18

Chi Square = 12.846 Pop Est Standard Err = 0.815 Lower Conf Interval = 18.000 Upper Conf Interval = 19.720

Capture Probability = 0.529 Capt Prob Standard Err = 0.108 Lower Conf Interval = 0.301 Upper Conf Interval = 0.758

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 16.28003 .

______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Smallmouth bass

Removal Pattern: 0 1 0 0 0 Total Catch = 1 Population Estimate = 1 (Using Program CAPTURE)

Chi Square = 0.000 Pop Est Standard Err = 0.2355 Lower Conf Interval = 1.000 Upper Conf Interval = 2.000

Capture Probability = 0.499769

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 0.00.

______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Riffle sculpin

Removal Pattern: 134 100 76 53 29 Total Catch = 392 Population Estimate = 475

Chi Square = 2.073 Pop Est Standard Err = 21.935 Lower Conf Interval = 431.789 Upper Conf Interval = 518.211

Capture Probability = 0.294 Capt Prob Standard Err = 0.027 Lower Conf Interval = 0.240 Upper Conf Interval = 0.347

______

Stream: NFFR below Granite Creek, 12 October 2010 Species: Prickly sculpin

Removal Pattern: 7 2 0 1 0 Total Catch = 10 Population Estimate = 10

Chi Square = 3.159 Pop Est Standard Err = 0.219 Lower Conf Interval = 10.000 Upper Conf Interval = 10.495

Capture Probability = 0.667 Capt Prob Standard Err = 0.131 Lower Conf Interval = 0.369 Upper Conf Interval = 0.964

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 9.504653 .

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Rainbow trout

Removal Pattern: 39 6 5 Total Catch = 50 Population Estimate = 50

Chi Square = 4.603 Pop Est Standard Err = 1.025 Lower Conf Interval = 50.000 Upper Conf Interval = 52.061

Capture Probability = 0.758 Capt Prob Standard Err = 0.064 Lower Conf Interval = 0.629 Upper Conf Interval = 0.886

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 47.9394 .

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Hardhead

Removal Pattern: 0 1 1 Total Catch = 2 Population Estimate = 2

Chi Square = 3.243 Pop Est Standard Err = 1.876 Lower Conf Interval = 2.000 Upper Conf Interval = 25.834

Capture Probability = 0.400 Capt Prob Standard Err = 0.625 Lower Conf Interval = -7.545 Upper Conf Interval = 8.345

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -21.83389 .

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Sacramento pikeminnow

Removal Pattern: 1 0 0 Total Catch = 1 Population Estimate = 1 (Using Program CAPTURE)

Chi Square = 0.000 Pop Est Standard Err = 0.00014 Lower Conf Interval = 1.000 Upper Conf Interval = 2.000

Capture Probability = 0.999555

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 0.00.

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Sacramento sucker

Removal Pattern: 3 0 0 Total Catch = 3 Population Estimate = 3 (Using Program CAPTURE)

Chi Square = 0.001 Pop Est Standard Err = 0.0000 Lower Conf Interval = 3.000 Upper Conf Interval = 4.000

Capture Probability = 0.999796

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 2.00.

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Smallmouth bass

Removal Pattern: 1 1 0 Total Catch = 2 Population Estimate = 2

Chi Square = 0.929 Pop Est Standard Err = 0.384 Lower Conf Interval = 2.000 Upper Conf Interval = 6.884

Capture Probability = 0.667 Capt Prob Standard Err = 0.384 Lower Conf Interval = -4.217 Upper Conf Interval = 5.550

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -2.883589 .

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Riffle sculpin

Removal Pattern: 44 25 22 Total Catch = 91 Population Estimate = 130

Chi Square = 0.903 Pop Est Standard Err = 23.865 Lower Conf Interval = 91.000 Upper Conf Interval = 177.252

Capture Probability = 0.329 Capt Prob Standard Err = 0.090 Lower Conf Interval = 0.151 Upper Conf Interval = 0.506

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 82.7478 .

______

Stream: NFFR at Rodgers Flat (Main Channel & Side Channel combined), 13 October 2010 Species: Prickly sculpin

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Rodgers Flat Site – Main Channel vs Side Channel

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Rainbow trout

Removal Pattern: 35 6 4 Total Catch = 45 Population Estimate = 45

Chi Square = 2.798 Pop Est Standard Err = 0.935 Lower Conf Interval = 45.000 Upper Conf Interval = 46.884

Capture Probability = 0.763 Capt Prob Standard Err = 0.067 Lower Conf Interval = 0.628 Upper Conf Interval = 0.897

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 43.11615 .

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Rainbow trout

Removal Pattern: 4 0 1 Total Catch = 5 Population Estimate = 5

Chi Square = 2.796 Pop Est Standard Err = 0.444 Lower Conf Interval = 5.000 Upper Conf Interval = 6.231

Capture Probability = 0.714 Capt Prob Standard Err = 0.222 Lower Conf Interval = 0.099 Upper Conf Interval = 1.330

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 3.768828 .

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Hardhead

Removal Pattern: 0 1 1 Total Catch = 2 Population Estimate = 2

Chi Square = 3.243 Pop Est Standard Err = 1.876 Lower Conf Interval = 2.000 Upper Conf Interval = 25.834

Capture Probability = 0.400 Capt Prob Standard Err = 0.625 Lower Conf Interval = -7.545 Upper Conf Interval = 8.345

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -21.83389 .

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Hardhead

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Sacramento pikeminnow

Removal Pattern: 1 0 0 Total Catch = 1 Population Estimate = 1 (Using Program CAPTURE)

Chi Square = 0.000 Pop Est Standard Err = 0.00014 Lower Conf Interval = 1.000 Upper Conf Interval = 2.000

Capture Probability = 0.999555

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 0.00.

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Sacramento pikeminnow

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Sacramento sucker

Removal Pattern: 3 0 0 Total Catch = 3 Population Estimate = 3 (Using Program CAPTURE)

Chi Square = 0.001 Pop Est Standard Err = 0.0000 Lower Conf Interval = 3.000 Upper Conf Interval = 4.000

Capture Probability = 0.999796

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 2.00.

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Sacramento sucker

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Smallmouth bass

Removal Pattern: 1 1 0 Total Catch = 2 Population Estimate = 2

Chi Square = 0.929 Pop Est Standard Err = 0.384 Lower Conf Interval = 2.000 Upper Conf Interval = 6.884

Capture Probability = 0.667 Capt Prob Standard Err = 0.384 Lower Conf Interval = -4.217 Upper Conf Interval = 5.550

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -2.883589 .

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Smallmouth bass

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Riffle sculpin

Removal Pattern: 39 23 17 Total Catch = 79 Population Estimate = 105

Chi Square = 0.250 Pop Est Standard Err = 16.465 Lower Conf Interval = 79.000 Upper Conf Interval = 137.600

Capture Probability = 0.369 Capt Prob Standard Err = 0.092 Lower Conf Interval = 0.187 Upper Conf Interval = 0.551

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was 72.39957 .

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Riffle sculpin

Removal Pattern: 5 2 5 Total Catch = 12 Population Estimate = 27

Chi Square = 1.940 Pop Est Standard Err = 38.152 Lower Conf Interval = 12.000 Upper Conf Interval = 105.441

Capture Probability = 0.174 Capt Prob Standard Err = 0.297 Lower Conf Interval = -.438 Upper Conf Interval = 0.786

The population estimate lower confidence interval was set equal to the total catch. Actual calculated lower CI was -51.44098 .

______

Stream: Rodgers Flat Main Channel, 13 October 2010 Species: Prickly sculpin

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______

Stream: Rodgers Flat Side Channel, 13 October 2010 Species: Prickly sculpin

Removal Pattern: None Captured Total Catch = 0 Population Estimate = 0

______