Hood River bull trout are geographically restricted to two local populations.  The Clear Branch local population occurs in Laurance Lake and tributaries upstream of Clear Branch Dam, and the Hood River local population is restricted to the mainstem Hood River and the portion Middle Fork Hood River downstream of the dam.  The status of both populations is extremely precarious.  The Clear Branch population is at risk of a random extinction event due to low numbers, isolation and limited spawning habitat.  The Hood River population is threatened by passage barriers, unscreened irrigation systems, impaired water quality and periodic siltation of spawning substrate by glacial outbursts. 

Beyond a general knowledge of the distribution of Hood River bull trout and the nature of anthropogenic factors that potentially restrict their connectivity, little is known about this recovery unit.  For example, the abundance of each population and the association of fluvial adults and headwater natal populations is not understood.  Further, the extent of migration into the mainstem Columbia River and associated distribution is unknown.  The degree to which irrigation and hydropower diversions hamper connectivity within the Hood River basin is also poorly understood. 

In 2006 the Native Fish Investigations Project initiated an effort to investigate the abundance and migration patterns of Hood River bull trout.  Specifically, we plan to determine the distribution and abundance of natal populations and investigate the link between migratory individuals captured at the Powerdale dam and the lower Middle Fork to populations in natal headwater habitats.  We will also investigate the extent that Hood River bull trout use the mainstem Columbia River and neighboring Columbia River tributaries.  Finally, we will assess the impacts of selected irrigation systems on migrating subadult and adult bull trout.

Annual Reports and Publications: