Diel Movement and Habitat Use of California Golden Trout in the Golden Trout Wilderness, California

Abstract

I used radio transmitters to determine the diel habitat use and movement patterns of California golden trout Oncorhynchus mykiss aquabonita inside and outside cattle exclosures on the South Fork Kern River, Golden Trout Wilderness, California. Twenty-three golden trout were monitored from September 10 to 19, 1993, during 216 diel-tracking hours at four study sites in upper and lower Ramshaw Meadow. No differences in distances moved or home ranges were detected between golden trout inside and outside exclosures. Mean home ranges were 18.5–54.0 m inside the two exclosure sites and 36.0–68.7 m outside the two exclosures. Most golden trout were found within 5 m of their previously recorded location at both upper (93.5% of 521 observations) and lower (92% of 394 observations) Ramshaw Meadow sites. Movement of individual fish varied: five fish moved less than 5 m throughout the 10-d study period, whereas 12 fish moved 100–608 m. Golden trout were active both day and night, and I observed them feeding throughout the night, even when water temperatures were as low as 2°C. At all study sites inside and outside exclosures, golden trout used three macrohabitats (pools, runs, and riffles) but selected pools in higher proportions than the more available runs. Throughout the study, golden trout were associated with nine habitat features (undercut banks, willows, bare banks, collapsed banks, open channel, aquatic vegetation, sedge, boulders, or rootwads) but were most commonly found near sedge and undercut banks.