This program contributes to the annual assessment of hatchery and wild salmon populations throughout the Columbia Basin.  Specifically, the goal of the coded-wire tag program, in conjunction with other Columbia River marking programs, is to tag a statistically valid number of coho and chinook salmon from each hatchery such that accurate estimates of survival and distribution in the ocean, in freshwater fisheries and escapement areas can be made.  Historically, the objective of the CWT program has been to release adequate numbers of CWT marked fish to ensure sufficient power of detecting a 50% difference in survival among compared groups (i.e. p= 1-0.95/2).  Each coded wire tag group represents a portion of the total hatchery production for the species.  Multiple tag groups at each hatchery represent different production scenarios, such as one portion of the production released at a different time or size than another portion.  This specific objective, and the means to achieve it and other marking objectives, may be affected by a new basin-wide marking plan currently under development by the co-managers in the Columbia Basin.  Although this plan is currently under development, additional marking and sampling likely will be required.  Much of that expanded work will require the use of the CWT coupled with electronic tag detection sampling programs.  

Specific tasks and methods follow:

a) Determine groups to be tagged and number of fish to tag.  This is a three step process.  First, all production releases are identified, based on program intent (ongoing regular smolt production), number of fish released (50,000 or more), and fish of an acceptable size (at least 2.0 gm/fish).  Second, groups with adequate tagging funded by other sources are eliminated from the list.  Finally, the number of fish to tag is determined based on the expected survival, generally 25,000 to 50,000 fish per group.

b) The identified groups of fish are tagged based on the manufactures recommendations and standard techniques for coded-wire tagging (Jenkinson and Bilton 1981).

c) Pre-release checks of 500 fish per group (PSC 1995b) are made at least 4 weeks after tagging (Blankenship 1981).  

d) All release information is reported to the Pacific States Marine Fisheries Commission and is available on their on-line computer database.
  
The expected outcome of continuing this project is to provide a long and consistent time series of survival and distribution data that can be used to measure trends in abundance of selected hatchery stocks.  In addition, the tagged hatchery stocks will be used to provide data relevant to the management of natural stocks, including many that are listed as threatened and endangered under the ESA.

Fish managers, researchers, mitigation agencies and others use the CWT release and recovery data to evaluate a number of administrative, management and environmental effects on salmon and steelhead.  For example, the harvest management agencies combine CWT data with other data and information to estimate the effects of harvest regulation on populations of salmon and steelhead.  Others use CWT data to estimate the rates of escapement into the wild of a population of hatchery fish.  Others, including BPA, use CWT data to determine survival of different hatchery operations, hence the effectiveness of the hatchery programs they fund.  Others use CWT data to determine the effectiveness of specific hatchery or other management actions.

Citations/reference materials used in statement of work.
Blankenship, L.  1981.  Coded-wire tag loss study.  Washington Department of Fisheries, Technical Report No. 65, Olympia, Washington.
Jenkinson, D.W., and H.T. Bilton.  1981.  Additional guidelines to marking and coded wire tagging of juvenile salmon.  Canadian Technical Report of Fisheries and Aquatic Sciences No. 1051.  24 pages.
Pacific Salmon Commission (PSC).  1995b.  Hatchery methodology workshop.  Held January 10th through 12th  1995, Seattle, Washington.