[4] Federal Scientists Slam FPC Survival Study
Scientists from NOAA Fisheries' Science Center in Seattle say the Fish Passage Center's latest draft survival study of hatchery and wild chinook in the Columbia and Snake rivers is misleading because its analyses are incomplete and don't "fully support" the findings in the Comparative Survival Study's executive summary.
The FPC draft has already been cited in court documents filed by BiOp plaintiffs a few weeks ago in their pursuit of more flow and spill for spring and summer dam operations.
"In our view," says the feds' Nov. 10 letter to the Fish Passage Center, "the important issues facing this region with respect to salmon recovery and hydropower operations warrant more in-depth analyses and a broader discussion of all relevant data concerning the nature and extent of hydropower system effects on salmonid stocks."
The feds' main gripes echo their own analyses that were previously published in an extensive technical memo, released in final form last February, that found PIT-tagged fish do not represent the untagged population.
So when the FPC study points out that smolt-to- adult return rates [SARs] seldom meet the 2 percent level previously identified by an earlier group of scientists (PATH) as minimum targets for recovery, it is "inadequate" on two counts, according to the feds. First, the PIT-tag SARs don't measure the SARs of the untagged population because they tend to underestimate survival of the population at large.
Secondly, recovery goals are still under development, so the FPC implies that any SAR below 2 percent is too low for stocks to recover. Technical teams are now developing criteria for recovering stocks, including SARs.
The Science Center also says the data is only partially analyzed, which fails to provide a "comprehensive evaluation" of the pros and cons of comparisons made between stocks from different regions and with different migration histories.
The feds say available evidence clearly shows that the benefit of transporting fish varies within each season, which is likely the result of fish size and the number transported, differences in predation rates, and changing conditions within the hydro system, estuary and near-ocean.
But the FPC analysis, based on annual survival results, "provides limited information and possibly misinforms managers about how to manipulate the system to provide the greatest benefits to fish," say the feds.
The Science Center points out that the draft Comparative Survival Study (CSS) ignores this altogether. The study is also at odds with earlier CSS results from a 2004 workshop that found SARs varied seasonally, the Center's critique says.
The feds took issue with statements in the CSS study's executive summary that implied transportation harmed wild fish because the average SAR of transported fish was lower than that of inriver migrants.
The feds pointed out that in 5 of 10 years, the point estimate of annual SARs for transported wild chinook was higher than inriver migrants.
They also said the CSS summary appears biased since it concluded that transportation had little or no benefit for wild chinook, yet it neglected to mention the overall 40-percent benefit of transportation for hatchery chinook and wild steelhead. They said that adds up to tens of thousands more hatchery chinook and 5,000 to 10,000 more adult wild steelhead that would not have returned had they not been transported.
The feds also said the analyses in the draft study don't reflect a consistent, statistically appropriate approach.
They say another potential bias arises from comparing non-detected fish to transported fish or others marked at dams. Since the non-detected fish pass lower Snake dams through the spillway or the turbines, they may be larger on average, as federal scientists have demonstrated in previous research, which suggests that these fish have different physiological traits than do detected fish, which can lead to differences in SARs.
Several years ago, federal scientists published findings that size alone correlated SARs, with smaller fish having correspondingly lower SARs.
The Science Center said the CSS treatment of upstream and downstream stocks "seems particularly biased," and asked why more downriver hatcheries weren't used in the comparisons. Since returns to upriver hatcheries vary considerably, they wondered if that wasn't true for downriver hatcheries as well. And, the feds point out, Idaho's McCall hatchery had much higher SARs for several years than did the downriver facility at Carson, near Bonneville Dam. -B. R.
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