2004 Annual Report pdf file

2004 Annual Report Abstract

Increased water flow (pulses) for hydroelectric generation and whitewater rafting may impact the distribution of native stream species because they represent significant deviations from the natural hydrograph. The research team conducted both experimental and field studies to assess the effect of these flows on four species of fishes that inhabit Californian rivers. Radio-tagged rainbow and brown trout were tracked during a single pulsed flow. No significant differences were found between the distances moved before, during, and after the release. Fish numbers were recorded in pools along this reach during snorkel surveys before and after the pulsed flow. The total fish density in each pool did not appear to differ before and after the pulse. The research team recorded the responses of juvenile rainbow trout, hardhead, and Sacramento suckers to artificially pulsed flows within a longitudinal flume. Although fish moved either upstream or downstream, the most common (or mean) position of the individuals was close to the center of the flume during pulsed flows. The distribution of individuals was also determined in a lateral displacement flume, consisting of a rectangular tank separated into a main channel that never drained and a sloped bank that alternately flooded and became exposed. Only three (7.8 percent) of the 38 fish placed within the apparatus became stranded. The field and laboratory studies described in the report provide an evaluation of the impacts of pulsed flows for recreational and commercial purposes on the behavior and movements of juveniles and adults of these species of fishes.

One of the sampling sites (near Gorilla Rock) in the American River before pulsed flow	One of the sampling sites below Chili Dam in the American River during pulsed flow
UCD biologists Lisa Thompson and Sarah Hamilton setting minnow traps for rainbow trout	Retrieving a minnow trap (near Gorilla Rock) and checking for trout size
UCD biologist Javier Miranda angling for rainbow trout (Note minnow trap at left foreground)	UCD biologists Peter Klimley and J. Miranda kayaking and fishing for rainbow trout
Preparing rainbow trout for surgery (radiotag implant) on the raft	Implanting radiotag into the abdominal cavity of rainbow trout
Rainbow trout recovering from surgery before release (Note antenna of radiotag along the ventral side of fish)	Radiotagged rainbow trout after release
Receiver and GPS unit for tracking radiotagged rainbow trout	Tracking radiotagged rainbow trout by triangulation

Photo credit: Department of Wildlife, Fish, and Conservation Biology, UCD
Please request permission from apklimley@ucdavis.edu for use of pictures