SPAWNING SEASON AND MICROHABITAT USE BY CALIFORNIA GOLDEN TROUT (ONCORHYNCHUS-MYKISS-AGUABONITA) IN THE SOUTHERN SIERRA-NEVADA

Spawning of California golden trout (Oncorhynchus mykiss aguabonita) was observed during May and June 1981, in Cottonwood and Mulkey creeks in the southern Sierra Nevada, California. Spawning began when daily water temperatures consistently exceeded 10-degrees-C, and was most intense between 1300 and 1600 h when water temperature was 16 to 18-degrees-C. Apparent election of redd site was based on water velocity and size of substrate, but not on water depth or distance to cover. Water velocity over redds was between 25 and 77 cm/s (mean 49 cm/s), and substrate in redds was gravel 2.0 to 19 mm in diameter. Golden trout constructed redds in water 4 to 24 cm deep. Redds averaged 0.22 m2 in surface area, and were within one-fourth of the stream width from the stream bank. Distance to cover from a redd often exceeded 15 m.