The goal of this study is to determine whether migration through Snake River dams and reservoirs causes extra mortality in Snake River yearling (spring/summer) Chinook salmon smolts.  Specifically, the study will determine if life-cycle survival downstream from McNary Dam is significantly higher for yearling Chinook salmon released into the Ice Harbor Dam tailrace than for counterparts which must pass three additional dams and reservoirs after release into the Lower Granite Dam tailrace.

Whether or not migration through the FCRPS, as currently configured, causes mortality to anadromous salmonid smolts that is not expressed until after they have passed through the system is one of the most important questions currently facing the region.  Experimentation will be required to confirm or refute this hypothesized mortality.  If it is real, a precise estimate of its magnitude will be essential to determine the degree to which dam removal would increase life-cycle survival.

The study proposed in this Scope of Work directly addresses RPA 195 and will provide data related to RPA 189 of the 2000 FCRPS Biological Opinion (2000 BiOp).  Study fish will also provide additional in-river survival estimates.  The large sample sizes will contribute to highly precise estimates of in-river survival which can be incorporated into Performance Standard tests as outlined in the 2000 BiOp.  In addition, the study directly addresses the need to evaluate extra mortality as described under RM&E Strategy 3: Critical Uncertainties in the Final Updated Proposed Action for the 2004 FCRPS BiOp Remand.

Work elements and milestones for the 2007 study year are provided below.  NMFS will keep the BPA COTR apprised of any work scheduling limitations or alterations.