Northwest Fisheries Science Center

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Document Type: Generic
Center: NWFSC
Document ID: 9020
Title: A study to compare smolt-to-adult return rates (SARs) of Snake River fall Chinook salmon under alternative transportation and dam operational strategies
Author: Tiffani M. Marsh, William P. Connor
Year: 2005
Place Published: Seattle, Washington
Publisher: National Marine Fisheries Service to the USACE and Action Agencies
Type of Work: Proposal of the

The goal of this study is to provide statistically valid information on the smolt-to-adult return rates of Snake River fall Chinook salmon Oncorhynchus tshawytscha under two alternative management strategies:  transportation around dams of the Federal Columbia River Power System and in-river migration under prevailing conditions.  Migration conditions are likely to change in future study years as the use of removable spillway weirs at Snake River dams, amounts of summer spill, and other structural or operational changes are made.  Although the primary aim of this proposal is to evaluate the effects of different management strategies on naturally produced fish, understanding how the different strategies affect the SARs of production fish released from hatcheries and at various offsite acclimation sites is also important.

To achieve the primary research goal outlined here, we will release two groups of PIT-tagged subyearling fall Chinook salmon in the Snake River upstream from Lower Granite Dam.  Prior to release, we will designate one group of fish as the transport group and the other as the in-river group.  Upon detection at a Snake River Dam, fish from the transport group will move through flumes to raceways for transport to below Bonneville Dam, while slide gates will direct fish from the in-river group to routes leading to the tailrace of the dam to continue in-river migration.

In 2005, groups will comprise both naturally produced fish and hatchery fish raised to a size at release as close as possible to that of naturally produced subyearling Snake River fall Chinook salmon (surrogates).  The majority of study fish will come from hatcheries because we do not have the ability to capture and tag sufficient numbers of naturally produced fish to conduct the studies outlined.  In 2006 and future years, the study scope will be expanded to include fall Chinook from Snake River production and acclimation facilities.

Theme: Recovery and rebuilding of marine and coastal species
Foci: Develop methods to use physiological, biological and behavioral information to predict population-level processes.