Winter Distribution and Habitat Associations of Juvenile Salmonids in the John Day River

As high summer stream temperatures wane during fall, juvenile salmonids rearing in tributaries to the John Day River migrate into and rear in the Mainstem John Day River prior to spring smolt emigration.  Identifying the stream reaches, channel units, and habitat characteristics these “fall migrants” are associated with is a first step toward improving the habitat necessary to complete this life history pathway.  We began our investigation of juvenile salmonid distribution and habitat association by surgically implanting radio transmitters into juvenile spring Chinook salmon and summer steelhead during fall 2013 and fall 2014.  We used fixed and mobile (raft-mounted) telemetry throughout winter to relocate tagged fish.  Juvenile salmonids in the Mainstem John Day River primarily occupied pools and fast water non-turbulent (glide) habitat units during winter months.  Juvenile salmonids were frequently associated with stream margins and occupied shallower and lower velocity waters during daylight hours.  Our results suggest that complex, low velocity stream margin habitat may be important for wintering juvenile salmonids in the Mainstem John Day River.