During the winter of 2000, Natural Resource Scientists, Inc. initiated research projects for the U.S. Fish and Wildlife Service to study the migratory behavior of juvenile chinook salmon in California's Central Valley Sacramento-San Joaquin Delta using radio-telemetry. Miniature radio transmitters were attached to juvenile late-fall-run chinook salmon and the fish were released at two locations in the north Delta: northern Georgiana Slough and the Sacramento River near Ryde. The telemetered fish were tracked on their outmigration through complex channels of the Delta using boat-mounted radio receivers. Individual fish were tracked up to 23 river miles from the release location. Upon release, most fish dispersed rapidly in a downstream direction until encountering the San Joaquin River (Georgiana release) and the Cache Slough confluence (Sacramento River release). At the latter two locations, telemetered salmon generally moved back and forth with the strong tidal flow (sometimes many miles in either direction) but still exhibited net downstream movement over several days. The graphic shows results for 50 radio-tagged juvenile salmon. Similar telemetry studies were performed by Natural Resource Scientists, Inc. for the U.S. Fish and Wildlife Service and CALFED agencies in the Central and South Delta during 2001 and 2002.


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