Project: Experimental and Field Studies to Assess Pulsed, Water-Flow Impacts on the Behavior and Distribution of Fishes in a California River

Introduction:

Hydroelectric plants release pulsed flows as byproducts of a load following electrical production, for recreational use, or sediment management. The overall impacts of these pulsed releases on the aquatic habitat and associated biotic communities are poorly understood. The Public Interest Energy Research Program (PIER) of the California Energy Commission (CEC) and the Division of Water Rights of the State Water Resources Control Board have established the Pulsed Flow Program through the Center for Aquatic Biology and Aquaculture (CABA) of the University of California, Davis (UCD), to address the ecological effects of manufactured or augmented flows from hydropower facilities on aquatic resources within California.

The program is specifically looking at the effects of pulsed flows on aquatic habitats and biotic communities in California streams and rivers. Other issues associated with such flows, for example, the economic consequences of providing augmented flows for white water rafting will not be addressed by this program.

Objectives:

Identify the effects of pulsed flows on native fish species in the American River by examining the potential of lateral and longitudinal displacement by conducting laboratory and field experiments.

Methods:

There are several components and stages to this two-year study including several field and laboratory studies to elucidate the effects of pulse flows on both adult and juvenile native fish.

Fig. 1. Longitudinal flume

Year 1: Laboratory Studies

Longitudinal Displacement

Longitudinal displacement of hardhead, rainbow trout and Sacramento suckers was studied using a 16.5 m long by 0.6 m wide flume located at the J. Amorocho Hydraulics Laboratory on the UC Davis campus. In an approximately two hour experiment fish were exposed to increasing and then decreasing flow intervals to simulate the ramping up and then down of stream flows during pulsed flow releases. Additionally substrate was added to the glass bottom of the flume to provide structure and cover for juvenile fishes. Velocities were characterized for the flume and for observed fish locations (Fig. 1).

Fig. 2. Lateral displacement and stranding flume. Depth varies from shallowest on the left to the deep channel on the right

Lateral Displacement and Stranding

The lateral displacement flume and the experimental conditions were designed to simulate a pulsed water release in order to test lateral stranding potential. The artificial stream channel, Lateral Displacement Flume, was located at the Center for Aquatic Biology and Aquaculture at UC Davis. Water depth increased from a minimum level then remained at a high or flooded level and the decreased back to the minimum depth. Rising and falling water levels mimic the daily flooding and dewatering of the bank habitat observed on the South Fork American River. Flooded bank use, stranding and behavioral observations were recorded (Fig. 2).

Year 1: Field Studies

Fig. 3. Snorkel survey for juvenile fishes in Silver Creek

Visual Implant Elastomer

Visual Implant Elastomer (VIE, Northwest Marine Technology) was used to observe the movement and potential displacement of juvenile fishes in the American River. This study was conducted solely at the Silver Creek field site due to difficulties locating and capturing juvenile fish at the South Fork American River below Chili Bar Dam. A 300 m section downstream of Camino Dam was divided into three 100-m reaches. Juvenile fish caught were marked with a unique color of the VIE that corresponded to one of the three 100-m reaches. Each stream reach has its own distinct mark color in order to track the movements of fish between reaches during snorkel surveys. Visual observations of fish densities were conducted day before the pulse and the day after the pulse by snorkeling the stream reaches (Fig. 3).

 

Fig. 4. Relocating tagged fish via radio telemetry on the South Fork of the American River

Radio telemetry

Lotek Wireless Inc. radio telemetry products and technology were utilized to track fish in the field. Fish were captured by hook and line. Trout were tagged with a digitally encoded Nano Tag (NTC 4-2L or NTC 6-2). Fish were tagged in the field and then after a 20-minute recovery period released at their capture location. Rainbow trout were tracked over a period of two weeks from a whitewater raft on the South Fork of the American River (Fig. 4), an area that is pulsed daily in the summer months. A comparative telemetry study at Silver Creek, a tributary of the South Fork, located fish on three occasions: before the one-day pulse, during the pulse and a week after the pulse. Silver Creek was pulsed only one day during the summer to scout the potential for future class V whitewater kayaking.

Progress

Fig. 5. Tagged trout release and relocation points in the South Fork of the American River (click image for larger size)

Radio telemetry

Three rainbow trout were caught, tagged and tracked on the South Fork of the American River from July 29th to August 12th. Two of the three tagged fish were removed from the system. Of the two fish removed: one was located a week after tagging on land and the other fish was not detected again after tagging. We were able to locate the third fish over several tracking events. This fish, code 10 (Fig. 5), moved within the river a maximum of 111 m and a minimum of 0 m between tracking events.

At the Silver Creek field site six brown trout and one rainbow trout were caught and tagged. These fish were radio tracked and positions determined on three occasions, the day before the pulse, the day of the pulse and a week after the pulse. We were able to locate five of the six fish during the study. Between tracking events fish moved from zero to 120 m (Fig. 6).

 

Fig. 6. Movements of tagged fishes before, during, and after flow event in Silver Creek.

Year 2: Electromyogram Tags

In this next year of studies we hope elucidate the physiological response of free-swimming fish to pulsed flows by using Lotek’s electromyogram (EMG) transmitter. These tags (CEMG-R11-18) transmit an integrated measurement of the action potentials within the red axial muscle or muscle activity. Fish will be tagged and then run in a Brett-type swimming respirometer in the laboratory before being released into the South Fork of the American River. The laboratory measurements of tail beat, ventilatory frequency and velocity will be correlated to field data in order to estimate the fishes’ energetic costs in response to pulsed flows. In addition, another set of fish will be tagged with the same Nano Tags used in year 1 to examine gross movement in response to pulsed flows (daily tracks of all fish) as well as more detailed hourly tracks of individuals.

Personnel

Sarah Hamilton

Stephanie Chun (participant year 1)

Joseph J. Cech, Jr., Ph.D.

Lisa C. Thompson, Ph.D.

A. Peter Klimley, Ph.D.

Department of Wildlife, Fish and Conservation Biology, UC Davis.

Acknowledgements

We would like to thank the Public Interest Energy Research Program (PIER) of the California Energy Commission (CEC) and the Division of Water Rights of the State Water Resources Control Board, and the Pulsed Flow Program through the Center for Aquatic Biology and Aquaculture (CABA) of the University of California, Davis (UCD).

Please also see the UC Davis Pulsed Flow Program website for additional project details and progress.

Click this link to see additional pictures of the field work.