Spring 2006 Gas Bubble Trauma Observed in Fish

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Spring 2006 Gas Bubble Trauma Observed in Fish
Preliminary Analysis

• Margaret J. Filardo

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• Fish were sampled at Lower Granite, Little Goose,
  Lower Monumental, McNary, Bonneville and Rock
  Island Dams.
• Over 9000 fish were examined for GBT during the
  spring migration season.
• COE Waiver Conditions for GBT are 15 of fish
  showing signs of GBT in non-paired fins.

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Summary

• At tailrace TDG levels near 120 the incidence of
  GBT in migrating salmonids was minimal.
• Project operations limitations at Lower Granite
  Dam resulted in higher TDG levels that showed
  effects of GBT in fish over long periods of time.
• Operations for management of excess market spill
  resulted in elevated levels of GBT in migrating
  salmonids.