Through Rocl<Y Reach
SUf\Zival estimate~ for. the passage of yearling fall chinool< salmon through Rocl<y Reach Fish Ecology and Rocf< Island Division Dams, 1998 Northwest Fisheries Science Center National Marine Fisheries Service by M. Brad Eppard, Steven G. Smith, Seattle, Washington Benjamin P. Sandford, Gordon A. Axel, John G. Williams, and Robert D. McDonald (Chelan County PUD No. 1) July 1999 Survival Estimates for the Passage of Yearling Fall Chinook Salmon through Rocky Reach and Rock Island Dams, 1998 by M. Brad Eppard Steven G. Smith Benjamin P. Sandford Gordon A. Axel John G. Williams National Marine Fisheries Service Northwest Fisheries Science Center Fish Ecology Division 2725 Montlake Boulevard East Seattle, Washington 98112 and Robert D. McDonald Public Utility District No. 1 of Chelan County Prepared for: Public Utility District No. 1 ofChelan County P. O. Box 1231 Wenatchee, Washington 98807 July 1999 ~ I ., INTRODUCTION The mid-Columbia Habitat Conservation Plan (HCP) includes a goal of 95% survival for juvenile salmonids passing the projects operated by Public Utility District No. 1 of Chelan County (District). To meet the objectives ofthe HCP, estimates ofmigrating juvenile salmonids are needed. In the spring of 1998, we conducted a pilot study designed to evaluate methods of estimating survival of downstream migrating salmon at the District's Rocky Reach and Rock Island Hydroelectric projects. Since 1993, the National Marine Fisheries Service (NMFS) has conducted survival studies on migrant juvenile salmonids in the Snake River (Iwamoto et. aI., 1994: Muir et. aI., 1995, 1996; Smith et. al., 1998). Survival estimation on the Snake River was made possible by the development ofthe passive integrated transponder tag (PIT tag), installation of detection and slide-gate systems at Snake River and Lower Columbia River danis, and adaptation of established statistical models for release-recapture data (Cormack, 1964; Jolly, 1965; Seber, 1965) to estimate survival for migrating fish.
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