Results of Lower Columbia River Survival Compliance Studies for 2012

An integrated compliance study was performed at McNary and John Day dams to estimate dam passage survival for spring stocks of yearling Chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss).  In the summer, an integrated four-dam study was performed at McNary, John Day, The Dalles, and Bonneville dams to estimate dam passage survival for subyearling Chinook salmon.  A total of 5789 yearling Chinook, 5797 steelhead, and 14,027 subyearling Chinook outmigrating salmon surgically implanted with acoustic- and PIT were used in the investigations. Assumptions of the virtual/paired-release design were met in the case of all eight-survival investigations.  Estimates of dam passage survival for yearling Chinook salmon at McNary and John Day dams met the 2008 Biological Opinion (BiOp) survival requirement for spring stocks.  The estimates of dam passage survival for steelhead at McNary and John Day dams also exceeded the BiOp survival requirement but the standard error at McNary was estimated to be too large.  Each of the four subyearling Chinook salmon studies were met the 2008 BIOP survival requirement for summer stocks.