Beginning in 1993, the National Marine Fisheries Service (NMFS) and the University of Washington (UW) began research to determine survival and travel-time characteristics of wild and hatchery-reared spring/summer Chinook salmon and hatchery steelhead migrating through Snake River dams and reservoirs (Muir et al. 2001a, 2001b; Skalski et al. 1998, Smith et al. 2002, Williams et al. 2001).  This research was expanded in 1995 to include Snake River fall Chinook salmon (Smith et al. 2003).  The initial goals of this research program were to 1) field test and evaluate the single-release, modified single-release, and paired-release Models for the estimation of reach and project survival, 2) provide annual estimates of reach and project survival with known precision, and 3) explore relationships among fish travel time, fish survival, and environmental conditions.  The first goal was addressed in detail during the first 5 years of research.   Presently, work continues on the second and third goals.   Additionally, we are now evaluating adult returns of PIT-tagged fish to further understand the relationships among juvenile survival, travel time, migration timing, and other factors, such as numbers of bypasses or passage routes, that juveniles encountered during their downstream migration to look for correlations with adult survival (Williams et al. 2005).  We also continue to evaluate violation of survival model assumptions, a necessary step in producing unbiased survival estimates.

The purpose of this project is to provide statistical input to the design and analysis for these smolt survival studies.  The analyses are based on data derived from passive integrated transponder tags (PIT tags) and radio-tags. Investigations focus on survival of wild and hatchery chinook and steelhead salmon in the Snake and Columbia Rivers.



REFERENCES


Muir, W. D., S. G. Smith, J. G. Williams, E. E. Hockersmith, and J. R. Skalski.  2001(a).  Survival estimates for PIT-tagged migrant juvenile Chinook salmon and steelhead in the lower Snake River, 1993-1998.  N. Am. J. Fish. Manage. 21:1-14.

Muir, W. D., S. G. Smith, J. G. Williams, and B. P. Sandford  2001(b).  Survival of juvenile salmonids passing through bypass systems, turbines, and spillways with and without flow defectors at Snake River dams.  N. Am. J. Fish. Manage. 21:135-146.

Skalski, J. R., S. G. Smith, R. N. Iwamoto, J. G. Williams, and A. Hoffmann. 1998.  Use of passive integrated transponder tags to estimate survival of migrant juvenile salmonids in the Snake and Columbia rivers.  Can. J. Fish. Aquat. Sci. 55:1484-1493.

Smith, S. G., W. D. Muir, J. G. Williams, and J. R. Skalski.   2002.  Factors associated with travel time and survival of migrant yearling Chinook salmon and steelhead in the lower Snake River.  N. Am. J. Fish. Manage. 22:385-405.

Smith, S. G., W. D. Muir,  E. E. Hockersmith, W. Zabel, R. J. Graves, C. V. Ross, W. P. Conner, and B. D. Arnsberg.  2003.  Influence of river conditions on survival and travel time of Snake River subyearling fall Chinook salmon.  N. Am. J. Fish. Manage. 23:939-961.

Williams, J. G., S. G. Smith, and W. D. Muir.  2001.  Survival estimates for downstream migrant yearling juvenile salmonids through the Snake and Columbia River hydropower system, 1966-1980 and 1993-1999.  N. Am. J. Fish. Manage. 21:42-49.

Williams, J. G., S. G. Smith, R. W. Zabel, W. D. Muir, M. D. Scheuerell, B. P. Sandford, D. M. Marsh, R. McNatt, and S. Achord.  2005.  Effects of the federal Columbia River power system on salmon populations.  NOAA Technical Memorandum, NMFS-NWFSC-63.