Non-native salmonids are impacting native salmonid populations throughout the Pend Oreille Subbasin. Competition, hybridization, and predation by non-native fish have been identified as primary factors in the decline of some native bull trout and cutthroat trout populations. Therefore, the goal of this project is to implement actions to suppress or eradicate non-native fish in areas where native populations are declining or have been extirpated. These projects have been identified as critical to recovering native bull trout and westslope cutthroat trout (WCT).

Until 1991, Graham Creek contained an allopatric WCT population that was isolated because of an impassable dam near its mouth.  In 1991, the dam failed and lower Graham Creek was invaded by non-native rainbow and brook trout.  The non-native fish invasion was limited to the lowest 700 m of the stream because a few boulders prevented upstream passage of non-native fish.  By 2003, no genetically pure WCT remained in the lower 700 m of Graham Creek and only pure westslope cutthroat were sampled above the boulder barrier.  However, the upstream section where WCT were isolated was at risk of invasion by non-natives if the boulders were shifted by high flows, bank failure, etc and the resulting conditions allowed upstream passage.  Therefore, in July of 2008 a fish management structure was constructed at the mouth of Graham Creek to preclude further invasion of non-native fish into the creek.  Prior to dam construction , electrofishing was completed in the lower 700 m to remove and relocate all captured fish below the new barrier site.  During construction of the fish management structure, the contractor underestimated the volume of large aggregate (rip-rap) required around the dam.  Therefore, in 2009 additional aggregate will be placed at the dam site.  Also, monitoring of the lower 700 m (by electrofishing) will occur in July 2009 to ensure no fish are breaching the barrier.

Westslope cutthroat trout have recently been extirpated in upper Cee Cee Ah Creek due to displacement by brook trout. Prior to implementing non-native fish removal and WCT translocation in upper Cee Cee Ah Creek, an extensive public outreach program was initiated.  In 2007, much of the effort for this project was made towards public education and involvement in using piscicides for native fish recovery.  To date, public acceptance of using piscicides as a management tool has been accomplished.  In 2008, Cee Cee Ah Creek was treated with rotenone to eradicate brook trout. Re-invasion of the treatment area is impossible due to the Cee Cee Ah Falls.  Another rotenone treatment is planned for 2009 to ensure that eradication is successful.  Once eradication is complete, cutthroat trout will be translocated from nearby watersheds.    

Bull trout and westslope cutthroat trout are threatened by non-native lake and brook trout in the Upper Priest Lake system.  The following excerpt was taken from the Idaho Department of Fish and Game (IDFG) 2007-2012 Fish Management Plan:

Tributaries in the Upper Priest Lake basin have the greatest potential to support large numbers of cutthroat trout and bull trout because they support the most miles of good steam habitat with the fewest number of brook trout.  Due to the smaller size and shallower depths of Upper Priest Lake, lake trout removal efforts would cost significantly less than in Priest Lake and would have a greater chance of success if strategies are developed and implemented to block lake trout migration through the Thorofare.  For this reason, we plan to continue removing lake trout in Upper Priest Lake through the end of this management period (2012).  If, by this time, lake trout control efforts are not resulting in significant improvements in the number of juvenile bull trout and westslope cutthroat trout are not seen in the lake, we will recommend alternative management in Upper Priest Lake.  If we are successful in removing lake trout, we would propose managing this lake for native fish only.  Currently, no lowland lakes in the Panhandle Region are managed for only native species.  We would not encourage the introduction or expansion of kokanee in this lake because kokanee can compete with cutthroat trout, especially in infertile lakes like Upper Priest Lake.

In 2009, this project will provide cost-share funding for the IDFG project and enable them to continue with lake trout removals in Upper Priest Lake and the Thorofare.