In their comments on the Borel Project First Stage Consultation Package, the Sequoia National Forest (SQF) requested SCE to conduct a quantitative fish population survey in the Borel Reach of the Kern River. The SQF asked that the survey use the methods and protocols established by SCE in their smallmouth bass study for the KR-1 Project. The study plan presented here was developed in consultation with the SQF, the California Department of Fish and Game, and other interested parties. The plan describes the objectives and methods of the survey and how the results will be reported, and provides a schedule of survey activities and deliverables.

The objectives of the fish population survey are to determine the fish species composition in the Borel Reach of the Kern River and to estimate, for each species present, the abundance by life stage, the size distribution and the total biomass. Results of the survey will be compared with results from previous fish population surveys in the Borel Reach to assess trends in abundance of native fish populations.

The survey will be conducted during a one-week period between March and May 2001. The sampling will be conducted during daylight hours.

Sampling for the fish population survey will be conducted at three stations in the Borel Reach of the Kern River. One station will be located a short distance downstream of the Lake Isabella Dam, one station will be located a short distance upstream of the Borel Powerhouse, and the third station will be located midway between these sites. At each station, three pool habitats will be surveyed by direct observation (mask and snorkel) and a 200-foot reach of shallow water habitat will be sampled by electrofishing. Each of these survey units will be measured using a hip chain and will be marked at each end with flagging, plastic orange squares, and metal tags. A hand held GPS unit will be used to determine the longitude and latitude of either the upper or lower boundary of the survey unit. All of the stations and survey units will be selected on the first day of the survey, prior to any sampling.

Measurements and observations of water quality and habitat characteristics will be made for each sampling station during the day that the station is sampled. Water and air temperatures, underwater visibility (for pool units), dissolved oxygen concentration and conductance will be measured and the average width, depth and gradient and maximum depth of the sampled stream reach will be estimated. The percentages of different habitat types, the surface area of trout spawning habitat in the reach, and the percentages of substrate types (fines, sand, gravel, rubble, boulder and bedrock) will also be estimated. All of the stations will be photographed.

Before conducting the snorkel census, all divers will snorkel at least one "non-sample" pool to ensure that each diver is familiar with identifying, counting, and estimating lengths of the fish present in this portion of the Kern River. This training procedure requires little time and ensures that uniform data-quality standards and survey procedures are followed throughout the census. The pool survey units will be sectioned into swimming lanes oriented parallel to the stream channel. The lanes will be marked with weighted ropes. Widths of the lanes will be determined based on measurements of underwater visibility to ensure that the lanes are set close enough together that a diver in the middle of the lane will be able to see fish at both lane margins. A diver will be stationed at the bottom boundary to monitor any fish movement into or out of the survey area during the period when lane lines are deployed. Snorkel surveys will be conducted between 10 AM and 4 PM, when light is adequate for underwater observation.

Based upon our years of experience conducting snorkel censuses in rivers with a mix of fish species similar to that in the Kern River, we have found that a "resting period" of fifteen minutes is adequate between laying lane lines and beginning the counts. No less than fifteen minutes after the lanes are set, a group of divers equipped with mask and snorkel and writing tablet will move upstream in the lanes, recording species and size class of the fish observed. The fish will be grouped into the following size classes: 0 – 75 mm, 76 - 149 mm, 150 – 299 mm, 300 – 400 mm, and greater than 400 mm. Each diver will be equipped with a wrist string marked at 75, 150, 300, and 400-mm lengths to be used for size-reference during the snorkel counts. Locations with cover will be inspected closely for concealed fish. If no natural barrier exists at the upstream boundary of the survey station, additional divers will position themselves in the water at the uppermost station boundary and record fish moving upstream out of the station reach.

The three-pass depletion method will be used for electrofishing. This method provides results that can be used to compute fish abundance. Block nets will be set at the upstream and downstream ends of the sampling reach to keep fish from leaving or entering the reach during the survey. No block net will be used at the upstream end if a natural barrier exists that blocks fish movement. The sampling will be conducted by three or more teams of biologists (one shocker and one netter per team) spread across the width of the river. The teams will make three separate sampling passes, moving together from the downstream to the upstream end of the sampling reach. All captured fish will be put in buckets equipped with aerators during each pass.

After each of the passes, captured fish will be identified, counted, measured and weighed. Scales will be taken from a subsample of the smallmouth and largemouth bass and hardhead captured. The scales will be stored in labeled scale envelopes and will be available to agency biologists for additional analysis on request. Prior to handling, all fish will be anaesthetized in CO₂ water (3:1 solution of river water to club soda) to minimize stress associated with the measurement/weighing procedures. During the second and third sampling passes, previously captured fish will be held in live cars outside of the survey area. After completion of the sampling, all fish will be allowed to fully recover before being released back into the study reach.

A draft technical report providing the results of the fish population survey will be prepared following completion of the fieldwork. The report will include a map showing the locations of the sampling stations and a table giving the water quality and habitat characteristics of the stations. The report will also provide tables with the results of the direct observation and electrofishing surveys. The table for the direct observation survey results will present numbers for each pool survey unit of each size class observed for each of the fish species present. The table for the electrofishing survey results will give numbers captured and average length and weight for each species at each station. The table will also provide computed abundance and biomass estimates, with 95 percent confidence limits for each species. The abundance estimates will be broken down by size class for the more abundant species. The report will also provide a graph of the combined length-frequency distribution of smallmouth bass from all the electrofishing stations.

In addition to describing the results, the report will compare the results with results of previous fish population surveys in the Borel Reach and will discuss implications regarding trends in fish abundances.

The fish population survey fieldwork will be performed between early March and early May 2001. The draft report will be made available about June 15 and a technical meeting to discuss the results will be held about July 15.

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