[4] Too Early To Evaluate '05 Summer Spill, Says Science Panel
The Independent Scientific Advisory Board that provides advice to NOAA Fisheries and the Northwest Power and Conservation Council has concluded that the effectiveness of last summer's court-ordered spill on juvenile fall chinook will not be known until adult fish return over the next few years. The ISAB was asked to look into the spill issue and the preliminary analyses produced to gage its effectiveness.
The added spill reversed a years-long policy of barging most fall chinook from Snake River dams. It was defended in court by federal attorneys who said leaving more fish inriver would likely kill more of them because of increased summer water temperatures. But U.S. District Court judge James Redden OK'd more spill after environmental and fishing groups filed a motion to have it boosted, though he turned down their request for more flows.
The ISAB looked at several preliminary reports on the spill, noting that most hatchery chinook had migrated before the spill regime even began.
The board said a preliminary analysis by the Fish Passage Center that compared survivals from 2005 to a few earlier years is of "limited utility" because of the variations in hydro operations from year to year, as well as the variations in run timing and passage behavior of the migrating fall chinook. The FPC study found the spill beneficial to juveniles and was cited by Redden in his late December decision to continue the increased summer spill operation in 2006.
The ISAB recommended a multiple-year study to measure effectiveness of the spill, with more monitoring of both juveniles and returning adults, along with evaluating consequences of changing spill for adult fish. The board also said more should be done to understand and estimate survival of the fall chinook that over-winter in hydro reservoirs and migrate early the following spring. -B. R.
The following links were mentioned in this story:
Biological Effectiveness of 2005 Summer Spill, ISAB, Jan. 18, 2006
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