Rapid Assessment of Reach Scale Movement and Habitat Associations of Juvenile Steelhead Using Portable PIT-Tag Antennas and Low Cost Geographic Positioning System

Fish select habitat based on the suitability of the habitat to provide areas to forage, rest, provide thermal refugia, breed, and avoid predators. Streams with a high degree of habitat complexity can potentially provide a greater range of habitats and thus decrease fish movement throughout a stream.  Conversely, poor habitat quality might make movement too risky, in which case poor quality habitat may be signified by a lack of movement. Evaluation of changes in fish movement patterns as a result of changes in their habitat has the potential to increase our understanding of factors limiting fish production.  We report on the use of portable PIT-tag antennas and hand held GPS units to monitor reach and stream scale movement and habitat use of juvenile steelhead in two tributaries to Asotin Creek, Washington. This study is part of a large scale (12 km) riparian fencing and LWD restoration project designed to result in a steelhead population level response. Steelhead greater than 70 mm were captured and PIT-tagged each year within twelve 500 m stream reaches during two sessions: summer and fall. Portable antenna PIT-tag surveys were then conducted to redetect tagged fish during three seasons: early fall, winter, and early spring. All redetected fish were spatially located using an integrated GPS unit. In addition, pools and large woody debris (LWD) were located with a GPS within the same reaches. These data were imported into ARC GIS and snapped to a digitized stream layer to allow for calculation of: fish movement between seasons, distance of each fish to pool and LWD habitat, spatial distribution of fish by season and size class. In several reaches, site fidelity was extremely high, although differences in reaches did exist.  These data will help better understand important aspects of juvenile steelhead ecology in southeast Washington and assess the effects of the planned LWD treatment on fish behavior and habitat use.