WHITE STURGEON SPAWNING MIGRATIONS AND LOCATION OF SPAWNING HABITAT IN THE SACRAMENTO RIVER, CALIFORNIA

Sixty sturgeon (59 white, Acipenser transmontanus, and one green, A. m edirostris) were tagged with radio transmitters in the lower Sacrament o River in late winter 1990 and 1991 and their movements during spawni ng migrations were followed. In spring 1991 and 1992, artificial subst rate samplers were deployed in various habitats in areas of the Sacram ento River used by spawning sturgeon. Upstream movement of tagged stur geon could be quite rapid, up to 25 km/d, and was often stimulated by small increases in river flow. Downstream movement of females, assumed to be post-spawning migrations, were also rapid, as fast as 91 km/d. Sturgeon eggs were taken at artificial substrate sites where depths ra nged from 1.8 to 4.6 m and flow velocities exceeded 1.0 m/s. Most spaw ning occurred from Knights Landing to several kilometers upstream of C olusa.