The salmon, hatched at the same time, were raised at Lyons Ferry hatchery and transported above Lower Granite in sequential releases. Survival rates ranged from 50 to 70 percent for earlier releases compared to less than 10 percent for later releases, Dreher said. The NMFS experimental design assumed that sequential releases of hatchery-raised fall chinook would not influence survival independent of flow, temperature, and turbidity. The Idaho review said that because flow rates, velocity, temperature and turbidity are so closely correlated, the NMFS study cannot properly judge the individual benefits to fish survival that flow components might provide. Understanding the effects of individual attributes of flow, particularly the usefulness of flow augmentation to compensate for the effects of reservoir impoundment on these attributes, is fundamental to determining the effectiveness of flow augmentation efforts for increasing survival of subyearling fall chinook salmon.
Flow is good for fish.
Dreher said the state is in the process of submitting the review to NMFS Science Center for review and comments. Montana Council member John Etchart asked Dreher if he would also be willing to submit the document to the Independent Scientific Advisory Board, which offers advice to both the Council and NMFS on science issues. Dreher said the state would not object. The Idaho review's call for more pointed research to sort out issues related to flow and salmon survival lines up with that of the Council. Comments regarding Idaho's review produced by the Fish Passage Center's Michele DeHart agree with the Idaho review's assessment of the correlation between flow, as well as between release timing and water temperature, on salmon survival.