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Methods for analysis of Chinook scales coastal and interior Oregon

Methods for analysis of Chinook scales coastal and interior Oregon. The Fish Life History Analysis Project Ben Clemens Lisa Borgerson Kanani Bowden Stephanie Gunckel. Fish Life History Analysis Project. Project history Project transitions Bottom-line: Chinook (and other spp.) monitoring

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Methods for analysis of Chinook scales coastal and interior Oregon

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  1. Methods for analysis of Chinook scalescoastal and interior Oregon The Fish Life History Analysis Project Ben Clemens Lisa Borgerson Kanani Bowden Stephanie Gunckel

  2. Fish Life History Analysis Project • Project history • Project transitions • Bottom-line: Chinook (and other spp.) monitoring • “Small, developing project with a big (and growing) plate”

  3. Scale Preparation • Most scales mounted on gummed cards • Plastic impressions made with a heat press • Scales of juveniles mounted on glass slides • Viewed with microfiche projector • Digital image system (Image Pro Plus, FlashPoint frame grabber, Leitz microsope, Cohu B&W camera)

  4. Fish Age • Age salmon by the number of winters • Fall/winter spawning salmon: Add “1” for the first winter

  5. Accuracy and Precision Accuracy • Test readers with known age scales--tagged fish (CWT, PIT) • Multiple readers (catch recording errors, lapses in judgment) Precision • Multiple readers-agree on interpretation diffs • Train by reading scales read by prev. readers • Test on a standard set of scales

  6. Validation • Known age tagged fish • Natural marks • Pedigree study • Mark and recapture • Marks on structure, chemical or temperature induced • Beamish, R.J. and G.A. McFarlane. 1983.. Trans. Am. Fish. Soc. • Campana, S.E. 2001. J. Fish Biol.

  7. Challenges • Sample sizes • Scale quality • Resorption/regeneration • Unclipped hatchery fish • Within-basin life history diversity • Ocean entrance: check vs. annuli • “Reservoir” life histories • South-migrating stocks: less distinct annuli • Lack of “known” age/disposition samples: Validation

  8. Challenges • “Small, developing project with a big (& growing) plate” • Ability to adapt (learn, grow, train new staff): challenging, given workload.

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