Intermittent Streams as Rearing Habitat for Sacramento River Chinook Salmon
Paul E. Maslin
William R. McKinney
and
Teri L. Moore
Abstract
Nonnatal rearing of juvenile chinook salmon (Oncorhynchus tshawytscha) was documented in several intermittent tributaries to the Sacramento River. Condition factors and length measurements of juvenile chinook captured in the intermittent tributaries were compared with those captured in the mainstem Sacramento River. The data suggests that juvenile chinook rearing in the tributaries grew faster and were heavier for their length than those rearing in the mainstem. Faster growing fish smolt earlier, and may enter the delta earlier in the year, before low water and pumping degrade rearing habitat. Optimal rearing conditions in the tributaries exist from approximately December through March. By April, conditions may be less favorable as temperatures rise to intolerable levels, and piscivorous fishes enter tributaries to spawn. Juvenile chinook entering the tributaries early in the year, such as winter and spring run, probably derive the most benefit from tributary rearing. Fall run, and especially the late-fall run, may be exposed to warmer than optimal temperatures, predation, and stranding. Documentation of nonnatal rearing is important for management of declining Sacramento River salmon populations. Actions may be necessary to protect intermittent stream habitat, and ensure adequate flows and habitat conditions for rearing.
To: Introduction