[2] BPA Says Latest Comparative Survival Study Incomplete
The Bonneville Power Administration has weighed in with a dozen pages of comments taking issue with the latest draft of the Comparative Survival Study, an ongoing report that has stirred controversy since its beginnings ten years ago. The controversy continues, and has been a major bone of contention.
CSS has been funded by the power-marketing agency since it started, much to the chagrin of some ratepayer groups. In fact, sources said that several individuals on the utility side of regional fish politics strongly urged BPA to file the comments.
The authors of the CSS, which include state, tribal and USFWS staffers, and led by Michele DeHart, director of the Fish Passage Center, have been under scrutiny since federal scientists and BPA raised significant questions over the value of the work and questioned whether the study should continue to be funded.
In 2005, BPA said the CSS upriver-downriver comparison intended to extract hydrosystem effects "has been misguided from conception." NOAA scientists said the CSS treatment of upstream/downstream stocks seemed "particularly biased."
But funding has been continued for the next six to nine months to allow CSS writers to complete a report that covers their 10-year-long investigation into survival of PIT-tagged wild and hatchery spring chinook and steelhead.
The draft 2006 CSS report was released for public comment in late October. BPA has weighed in again this year, though NOAA Fisheries did not comment on the latest draft at all.
After 10 years of paying for the CSS, BPA is still asking its authors to provide the underlying statistical framework and "explain how stated assumptions are used throughout the report."
BPA says that the CSS report has left out several important elements in its analysis that, if added, "could likely explain differential survival among PIT-tagged populations, particularly the factors that could help explain any difference in SARs [smolt-to-adult return rates] of up and down river stocks."
The debate over 'D'--that aspect of juvenile fish mortality that is "delayed" and occurs outside the hydro system--has been going on for years, ever since it was hypothesized in the mid-1990s during the PATH process, a regional and sometimes testy regional collaboration studying various aspects of the salmon recovery effort in the Columbia Basin.
Many state and tribal participants in PATH, plus USFWS biologists, supported the notion that barged and bypassed fish eventually died off at higher rates than fish that migrated inriver, which they said suffered ill effects from hydro passage as well. Confusion and years of wrangling ensued, leading to the concept of "differential delayed mortality," which proponents say shows upriver stocks died off at higher rates.
The controversy continues, and has been a major bone of contention during development of the latest fish passage survival model [COMPASS] being used in the hydro BiOp remand. Computer modelers and other biologists met recently in Portland to take another look at it, in the presence of the independent science board.
In the letter to the Fish Passage Center, Bob Austin, BPA's deputy director for fish and wildlife, cited previous comments from the science board that echoed their own call for "additional supporting data" and more descriptions of CSS methodology to allow a "disinterested third party to reproduce the analysis and conclusions."
The latest draft CSS report still clings to annual 'D' estimates for various stocks, despite criticism last year by both the feds and BPA, who said closer investigation of PIT-tagged fish has shown that survival to adulthood varied widely from one week's juvenile migration to another. The general implication was that transported fish survival improved greatly later in the spring, which suggested that ocean entry timing and fish size play important roles in ultimate survival.
But the latest CSS report says its authors found little evidence that size differences or entry timing between upstream and downstream stocks played much of a role in upstream/downstream comparisons.
NOAA scientists, in last year's comments, said they had evidence that smaller fish tended to take bypass routes at dams, (and then be barged), and that hatchery PIT-tagged fish returned at lower rates than the run at large. Furthermore, they had taken issue with comments in last year's draft CSS report that barging wild spring chinook showed little or no benefit for wild spring chinook, when CSS' own data showed benefits in five out of ten years.
The CSS authors added a statement to their conclusions in the final 2005 CSS to reflect the feds' concern. But in this year's draft, the statement about barging benefits for wild spring chinook was missing altogether.
The feds won't be calling CSS authors on the issue this time around, since they didn't send comments.
But results from their own studies put barging springers from Lower Granite Dam on the Snake River in a good light. Last month, NOAA Fisheries researcher Doug Marsh reported that returns from the 2003 outmigration outperformed inriver migrating (non-detected) chinook by 2.64 to 1.00. Barging from Little Goose showed benefits as well, with transported fish doing 60 percent better than inriver migrators.
The final 2006 CSS report was released Dec. 12, which included responses to some BPA comments, mainly in regard to statistical issues. CSS authors said some other BPA recommendations would be addressed in their upcoming "synthesis" report or other future analysis. The final 2006 report didn't include any comments about the benefit of barging wild chinook like last year's final report. -B. R.
The following links were mentioned in this story:
Latest draft of the Comparative Survival Study
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