Using Adult Coho Salmon to Re-Colonize Tributaries in the Yakima River Basin

Using Adult Coho Salmon to Re-Colonize Tributaries

in the Yakima River Basin

TODD H. NEWSOME

Yakama Nation Fisheries, Post Office Box 151, Toppenish, Washington 98948, 

GABRIEL M. TEMPLE

Washington Department of Fish and Wildlife, 201 North Pearl Street Ellensburg, WA 98926

DOUGLAS NEELEY

International Statistical Training and Technical Services, 712 12th Street, Oregon City, Oregon 97045, USA

Bill Bosch, DAVID T. LIND, and DAVID E. FAST

Yakama Nation Fisheries, Post Office Box 151, Toppenish, Washington 98948, USA

Taneum Creek is a moderately sized (fifth order) stream located on the Eastern slopes of the Cascade Range in central Washington State.  Prior to 1910, good numbers of silver salmon (coho) were reported to use the creek, but with the initiation of irrigation development, anadromous fish passage was blocked and the Taneum Creek coho runs were extirpated. In 1996, the Yakama Nation and cooperators initiated a project to determine the feasibility of reestablishing a naturally spawning coho salmon population in the Yakima River. The project succeeded in establishing natural spawning populations throughout the Yakima Basin.  In 2006, Phase II of the project was initiated with the focus primarily to test 3 different tools to re-colonize Yakima basin tributaries; summer parr plants, mobile acclimation, and adult coho salmon out planting.  During the fall of 2006, 300 hatchery adult coho salmon were captured and relocated into three 400 meter sections of Taneum Creek.  Approximately 50 males and 50 females were placed into each section.  Spawning success has steadily increased over the course of the study ranging from 49% in 2007 to 89% in 2010.  Naturally produced coho parr have been PIT tagged each summer to monitor parr to smolt survival to McNary Dam and current survival estimates range between 9 and 13%.  In addition to our Phase II evaluation of natural production, we have implemented an evaluation of ecological interactions associated with our coho reintroduction.  Thus far, coho reintroduction did not negatively affect rainbow trout abundance in our experimental reaches, although we did observe decreased rainbow trout size (P<0.001).  We did not observe differences in instantaneous growth in length (P<0.09) or weight (P<0.27) of tagged rainbow trout in areas with high and low densities of naturally produced coho parr.  Additional years of data will increase the power of our tests to detect significant ecological interactions if they are occurring.