Assessing the Movements of Fluvial and Adfluvial Bull Trout in the Methow Core Area and Twisp River Using PIT Tags: Applications for Recovery Prioritization

In 1999 bull trout were listed as threatened species in the Pacific Northwest.  Since then researchers have attempted to evaluate the factors for their decline. To support this effort, since 2010 Douglas County Public Utility District has incidentally captured and tagged over 100 adult bull trout during anadromous salmonid broodstock and reproductive success studies.  These bull trout were subsequently PIT tagged, released, and monitored over a three year period.  This movement and habitat use data provides an opportunity to examine the life histories and population strength of bull trout in the Twisp River located in the state of Washington.  Information collected also contributes to Douglas County PUD’s FERC license obligations and continues to develop our understanding on an under-researched species in the Pacific Northwest.  Together we found that migration and movement patterns were highly predictive and repetitive over the three year period.  Predictive movements appear to be related to spawning migrations and seeking suitable foraging and/or overwintering habitats.  We argue that results should be considered when implementing management strategies and meeting recovery objectives and goals.  Finally, these results can be used to direct future research on the relative importance of threats to bull trout recovery.