Efforts to Reinvoke the Steelhead Life History in Beaver Creek: Will Barrier Removal Alone Suffice?

A century-old barrier was removed in 2005 from Beaver Creek, a tributary to the Methow River of the Columbia River basin in northcentral Washington.  A primary goal of the project was to allow for natural recolonization of steelhead without hatchery supplementation.  To track the success of this recolonization, we PIT tagged individual juvenile rainbow trout and used a network of fixed instream PIT tag interrogators to gage response in terms of expression and distribution of anadromy within the Beaver Creek watershed.  In addition, we compared the genetic analysis from 16 microsatellite markers from juvenile rainbow trout (2004-2005 versus 2009-2010) and for presence of marine-derived isotopes across trophic levels collected at various locations in the watershed.  These efforts allowed us to track the upstream progression of recolonization through time and to understand the role of existing resident populations of rainbow trout in the recolonization process.  Success of cohort-specific strategies that contribute to smolt production was linked to geomorphic constraints and variation in environmental conditions.  Rearing environment had a substantial influence on growth, survival, expression of anadromy, and contribution to overall smolt production.  This information is being used to guide future salmonid restoration efforts focused on enhancing longitudinal and lateral connectivity.