Salmon specialists throughout the Pacific Coast indicate that the winter-run Chinook salmon is restricted to California's Sacramento River system. The characteristics and habits of the race are unique in the following respects: Fresh-water holding period, December to April; spawning period, April into July. The up-migration is concurrent with the late segments of the fall run, but the adults are distinguishable by the green condition of the gonads. The down-migration is concurrent with that of the spring-run fry, but the migrants are 2-inch or larger fingerlings. Evidence is lacking to determine whether there is an earlier down-migration of fry. The race appears to hold great promise as a stock to be introduced into areas where May-August temperatures are 42.5 degrees - 57.5 degrees F., for it supports superb angling during the fresh-water holding period. Water temperatures in May through August are seen as the factor limiting the natural extension of the range of the race.

Outmigration is an important life stage for Chinook salmon (Oncorhynchus tshawytscha) survival in the Sacramento River, and yet our understanding of their behavior and needs during this time is limited. To gain a better understanding of their survival and movement rates during outmigration, late fall run Chinook salmon smolts were tracked using acoustic telemetry techniques. Habitat features were measured and quantified throughout the study area to evaluate how Chinook salmon respond to key levee features including shade, instream woody material, and aquatic vegetation. The overall average movement speed through the entire study area was 0.77 m/s with an overall survival of 86%. Based on multiple linear regressions, vegetation was found to have the largest effect on speed with fish slowing down with increased vegetation cover. Shade, river mile, and velocity also had significant effects on movement speeds, but instream woody material was not significant. The result for woody material was surprising since it was anticipated to have a large impact on movement speeds. A positive correlation was found between faster fish movement speeds and higher survival. No evidence of diel movement patterns was found after releasing the fish. These finding can help managers create sites better designed to help Chinook salmon in the Sacramento River system. Results from this paper indicate that the type of woody material being installed might not be appropriate for this life stage of salmon.