Report Abstract

from: McIntosh, B.A. and H.W. Li. Final Report - Klamath Basin Pilot Project:
Coldwater Refugia Study and Videography. Oregon State University. 18 Dec. 1998

We found forward-looking infrared (FLIR) to be an effective, highly accurate, and cost effective method to map stream temperatures in the mainstem Klamath River. Results from the July 1998 flight matched patterns observed from instream monitors and modeled temperatures. Stream temperatures were mapped from just above Seiad (river km 217) to just above Cottonwood Creek (river km 297) and ranged from 23.8 to 26.8oC (mean = 25.4 oC). These temperatures are just below or exceed the upper incipient level for salmonids. This suggests that temperature is a bottleneck for life stages of wild salmonids that rear or hold in this section of the Klamath River during July and August. Elevated stream temperatures should not affect hatchery reared chinook salmon as they are exposed to lower stream temperatures during their migratory phases. Potential thermal refugia were only found in association with tributary junctions, thermal refugia were not associated with individual channel units. We also radio-tagged nineteen adult fall chinook salmon with temperature sensitive tags in September 1996 and tracked them until late October 1996. There was no evidence that migrating adult fall chinook salmon were behaviorally thermoregulating during their upstream migration. Water temperatures were moderate for salmonids during the fall migration. Daily maximum temperatures did not exceed 20.0oC, but were typically above 15.0oC.