[3] Science Panel Slams FPC's Latest Survival Study

A group of independent scientists who try to sort out sticky scientific issues in the salmon recovery realm have joined with earlier critics of a controversial chinook survival study overseen by the Fish Passage Center that has been going on for the past 10 years.

Responding to questions from the Northwest Power and Conservation Council, the Independent Scientific Advisory Board issued its review of the 2005 Comparative Survival Study [CSS] on March 15, just a couple of days before the FPC was scheduled to close its doors. While it said the design, implementation and interpretation of the statistical analysis "underpinning" the report were very good, the ISAB had broader concerns about the study design, and said many of the study assumptions need to be tested.

The board was also "concerned" about the basic premise of the study--that PIT-tagged fish could serve as surrogates for the unmarked population. NOAA scientists have found that using only PIT-tagged fish may severely underestimate survival of the run at large.

The ISAB noted that the NOAA Fisheries review of CSS last November pointed out that PIT-tagged fish returned at about half the rate of untagged fish. "The data to make these comparisons [with untagged fish] is in the CSS report, but the CSS authors do not make the comparisons," said the ISAB review.

The ISAB also agreed with the criticism leveled by BPA and NOAA Fisheries at the study for its use of only one downriver hatchery site to test the hypothesis that smolt-to-adult returns for salmonids would be lower for fish passing more dams. The ISAB called this hypothesis "a prime motivation" for the study in the first place.

They also took issue with the study using only annual SARs, when the smolt-to-adult return rates vary as much within years as between them.

"It has been an ongoing criticism of the FPC that they do not further refine their data to within-year conditions," said the latest review, noting that "the ISAB made similar comments in 2004 on the FPC analyses of flow augmentation."

The new ISAB review also agreed with an earlier ISAB comment on the CSS that said "formulas are complicated, convoluted, and in general, very unsatisfactory from a statistical point of view."

The science board took stock of the BPA and NOAA Fisheries reviews in its report, as well, but didn't include BPA comments that pointed out earlier versions of CSS used different downriver sites for comparing upriver and downriver stocks.

"Initially, the study started with multiple downriver stocks," said the November 2005 BPA review, "but these hatcheries have been reduced to only the Carson NFH, when the other hatcheries had SAR values less than upriver hatcheries. If investigators eliminate all the information that does not conform to their conceptual model, as in the case of the upriver-downriver comparison, you are often left with nothing but coincidences or wishful thinking."

Reviewers from the NMFS Science Center in Seattle had said the CSS summary appeared 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 Science Center also noted that 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 pointed out that Idaho's McCall hatchery had much higher SARs for several years than did the downriver facility at Carson, near Bonneville Dam.

The feds had also taken 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.

But data on wild chinook returns are skimpy, with some earlier years in the study showing only single-digit returns. The ISAB said 2001, with its large numbers of transported fish during the drought, was the only year in the analysis that provided any meaningful information on the relative survival of transported and in-river smolts. Transported wild chinook averaged nine times better survival than inriver migrants that year. -B. R.

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