Trout behavior and responses to pulsed flows: investigations utilizing electromyogram telemetery

Transcription

1 Trout behavior and responses to pulsed flows: investigations utilizing electromyogram telemetery Sarah A. Hamilton, Dennis E. Cocherell, Gardner J. Jones, and Javier B. Miranda, A. Peter Klimley, Lisa C. Thompson, Joseph J. Cech, Jr. Wildlife, Fish, & Conservation Biology Department, UC Davis

2 Pulsed Releases Water is artificially released into rivers The timing and frequency deviates from normal hydrograph Do these pulsed releases adversely affect the behavior of fishes? Before a pulsed release After a pulsed release

3 American River Watershed

4 Whitewater Rafting Water released from Chili Bar Reservoir into the South Fork of the American River for whitewater rafting

5 Pulsed Releases in the South Fork One pulse release per day Release increases from 5 m 3 s - to 40 m 3 s - Artificial releases from mid July to vember

6 Radio Telemetry Radio beacon inserted into the body cavity of 0 small and large rainbow trout Trout bearing beacon localized using directional antenna

7 Pulsed Flows N= Water discharged daily from Chili Bar Dam, increasing the flow from 5 m 3 s - to 40 m 3 s - for four hours N=

8 Distance of Movement Initial downstream or upstream movement during Week for six, but little movement during Weeks 2-2, 2 except for RT2 Little movement downstream or upstream during Weeks 5-45

9 Longitudinal Displacement ID TL Mass (cm) (g) RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT Rapids Rapids

10 Statistical Analyses Longitudinal Displacement Variables Units DF F P Significant α 0.05 Size Large, small Weight g Health Index Release Location Rkm 6.,Rkm Week Habitat Rapid, Run, Pool River Location Main Channel, Margin Mean Weekly Day Peak Flow m 3 s Mean Weekly Night Peak Flow m 3 s

11 Electromyogram Telemetry Transmitter telemeters index of the electrical activity generated by muscle activity Ideal for determining whether trout are forced to exert more energy during pulsed flows Electrodes must be inserted into musculature

12 Respirometry Trout are placed in a chamber and water flow is regulated to to produce known swimming speeds Investigators record tail beat frequency as well as oxygen concentration to obtain measures of swimming activity and oxygen consumption

13 Trout Metabolism Swimming speed is related to both EMG activity and oxygen consumption EMGs measured during the pulsed flows can be related to metabolic output

14 Electromyogram Tagged Fish Fish Tag Rel. Tracking Dates for Electromyogram Tagged Fish ID Code Loc. August September October RTE 5 HL RTE 2 4 HL RTE 3 3 CL RTE 4 6 CL RTE 5 HL RTE 6 9 HL RTE 7 22 HL RTE 8 20 HL * RTE 9 2 HL EMGs recorded during pulsed flow cycle on 3-4 days.

15 Multivariate Analysis Effectors DF F P Significant α 0.05 Sex male, female, unknown U crit cm/s Standard Length cm Weight g River Mile mi Discharge f 3 s Pulse Code Pulse, Rising, Peak/Stable, Decrease Yes Days in the River day Rate of movement mhr Statistically significant relationship with stage of pulse

16 Greater Exercise during Rising Stage? Smallest percentage of fish swimming <50% Ucrit Largest percentage exceeding highest calibration speed Pulse Stage < 50 % Ucrit mean ± se < 00 % Ucrit mean ± se > Highest Calibration Speed mean ± se Pulse 62.5 ± ± ± 4.4 Rising 54.2 ± ± ± 7.6 Stable Peak 62.7 ± ± ± 6. Decreasing 63.0 ± ± ± 3.9

17 Swimming Tactic during High Flows Swim at rates from cm s - only during flows slower flows, <45 cm sec -. Likely seek out hydrodynamic refuges such as eddies behind rocks.

18 Effect of Rafting on Trout Solid circles indicate speeds of trout in the absence of rafters, clear circles in their presence. te highest swimming speeds recorded as rafters passed by fish. Anecdotal observations

19 Tracking Studies Conclusions Negligible transport of fish downstream during pulsed flows. Electromyogram Studies Trout swim more vigorously during onset of pulsed flow. Yet eventually seek refuge from strong flows in eddies behind rocks. The passage of rafts may elicit a withdrawal response from trout, resulting in a rapid burst of speed.

20 Funding / Acknowledgements This research was supported by Public Interest Energy Research Program (PIER) of the California Energy Commission Division of Water Rights of the State Water Resources Control Board Pulsed Flow Program of the Center for Aquatic Biology & Aquaculture (CABA) of the University of California, Davis Sacramento Municipal Utility District (SMUD) provided information on creeks that were scheduled for pulsed flows, & assistance during the field work at Silver Creek