Review of Comparative Survival Rate Study of Hatchery PIT Tagged Chinook

read full document >

Findings
  • The number of PIT tags to be applied is appropriate to the purposes of the study.
  • The utility of PIT tagging now and in the future goes beyond the immediate purposes of this study. Annual PIT tagging of similar numbers of juvenile salmon as a basis for management of the hydroelectric system is advisable.
Points of concern
  • Questionable comparability of results on hatchery spring chinook to those that would be obtained from naturally produced spring chinook, other chinook life history types, and other life history types of other species of salmon, increases the uncertainty of advice given to managers.
  • The two hatcheries most distant from the hydroelectric system in the 1997 study, Pahsimeroi and McCall, are not proposed for tagging in 1998. Loss of information on geographic variation in survival to Lower Granite Dam that could be important to management should be avoided.
  • Comparability of survivals of PIT tagged juvenile salmon relative to survivals of juveniles not PIT tagged is unknown.
  • The present suite of survival estimation programs, including this project, does not provide estimates of survival applicable to the entire Snake-Columbia River federal hydroelectric system.
  • Coordination and cooperation among agencies applying PIT tags and other marks may not be sufficient to insure the maximum return on the tagging dollar.
Recommendations
  1. Fund the proposed study.
  2. So long as the present configuration and operation of the federal hydroelectric system exists, extend (or continue) PIT tagging to include naturally reproducing populations of spring chinook whenever population sizes may permit. Continue PIT tagging other chinook life history types, and extend PIT tagging to other life history types of other species of salmon, including steelhead, whenever possible.
  3. Apply enough PIT tags to spring chinook production from Kooskia, Pahsimeroi, McCall, Sawtooth, and Clearwater (Powell, Crooked River and Red River Ponds) hatcheries to estimate survival to Lower Granite Dam. Whenever possible apply enough PIT tags to spring chinook at these hatcheries to estimate survivals to McNary Dam.
  4. Compare rates of return to each hatchery of PIT tagged and untagged adults to establish degree of comparability of survivals of PIT tagged juvenile salmon to survivals of juveniles not PIT tagged. To investigate rate of shedding of PIT tags through the adult stage, and where straying of adults from another hatchery is possible, investigate thermal mass marking of all hatchery production. Where smolt to adult survival of PIT tagged fish is compared to that of coded wire tagged (CWT) fish, develop a procedure to study tag loss and to compare rate of return of PIT to CWT within the hatchery release.
  5. Make estimates of survival applicable to the entire Snake-Columbia River federal hydroelectric system as soon as possible.
  6. Use the funding proposal format to promote coordination and cooperation among agencies applying PIT tags and other marks by including a list of other agencies marking salmon and steelhead of the same origin in the proposal, along with comments from those other agencies. Sponsor an interagency workshop on the use of tagging data at five-year intervals. The workshop would produce consensus recommendations and procedures for coordinating tagging activities.

This website was archived in May 2018.

Go to this page on the new site or keep browsing the old site.

Contact Eric Schrepel with any questions or requests for our new (current) site, thank you.