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PATH Modelers Announce Year-End Results

by Bill Rudolph
NW Fishletter, December 15, 1998

1999 Portland billboard reads, PATH modelers have wrapped up another year of wrestling with the demon uncertainties of salmon recovery. It's all documented in more than 200 pages of charts, bar graphs and tables that spell out what close to two million dollars' worth of salmon modeling buys in a year's time.

The region got an early taste of the latest PATH effort when the group's facilitator, Dave Marmorek of Essa Technologies, reported on progress at last week's IT meeting in Portland. Environmentalists had spread the word that the document would probably come out in support of breaching lower Snake dams, and the room was full when Marmorek's turn began.

In October, Marmorek reported on the work of an independent panel of scientists commissioned by PATH to weigh evidence for various hypotheses regarding salmon recovery (See related story in NW Fishletter 68). More PATH analysis that used the weighted evidence found that breaching lower Snake dams would create an 80 percent probability of reaching the NMFS 48-year recovery standard for spring and summer chinook stocks. BPA participants and their consultants took issue with the evidence process and said the panel needed more information before they could adequately judge the value of competing hypotheses. The panel felt that the flow/survival relationship used in the states' and tribes' passage model had a better empirical fit than BPA's more complicated model that was calibrated with more recent data on juvenile survival in the mainstem Columbia and Snake rivers.

Last week, Marmorek said that PATH (using the weighted evidence) has found that breaching the lower Snake dams would result in only a 48 percent probability of reaching all three NMFS jeopardy and survival standards, but that such a strategy is still about twice as effective for reaching those goals as transporting fish. Further analysis that included modeling a drawdown of John Day reservoir boosted the probability to 62 percent.

Marmorek also said preliminary work that modeled the value of using an extra one million acre-feet of Idaho water for augmenting flows in the Snake and ending the transport program wouldn't be any better than keeping a maximized fish barging program in place.

Some PATH analysis has been done with fall chinook stocks, Marmorek reported, and indicates that breaching the lower Snake dams would have a 100 percent chance of reaching all NMFS standards, whether John Day was breached or not. A maxed transport program only had a 15 percent chance of reaching recovery and jeopardy goals, according to the PATH analysis.

Marmorek said that the scientists were taking a closer look at assumptions regarding fall chinook. The PATH modelers now assume that drawdown of the Snake dams doubles the upstream survival of the stocks. He said they are scrutinizing data to see if the assumption is valid.

PATH's initial look at increased bird predation in the estuary found that salmon-eating Caspian terns living near Astoria could reduce 48-year recovery probability (under current conditions) by 23 percent.

PATH modelers haven't taken a close look at what would happen to fall chinook stocks by changing in-river harvest rates, but found that either increasing or decreasing ocean harvest rates would have little effect on changing probabilities for recovery.

Facilitator Marmorek also outlined scenarios for experimental management to learn more about key uncertainties, another recommendation that came from the evidence-weighing science panel. The work would aim to get a better idea of the effectiveness of transportation, estimates of in-river survival, hatchery impacts, post-hydro survival and other related issues. Some proposed options had several observers muttering under their breath, such as calling for a four-dam drawdown, reduced transport and increasing and decreasing hatchery production.

"He's in never-never land," said Idaho irrigator spokesman Dewitt Moss after hearing Marmorek outline the experimental management options.

Estimates of in-river survival may be coming sooner than some think. Earlier at the meeting, NMFS spokesman Bill Hevlin said his agency will rely on the PATH analyses in the discussion of salmon recovery alternatives in its appendix to the Corps of Engineers' upcoming feasibility study on the future of lower Snake dams. Corps spokesman Doug Arndt said his agency's study will include recent NMFS PIT-tag survival work.

NMFS scientists using a trawl net to record PIT-tagged fish had reported preliminary results of Lower Granite-to-below-Bonneville survival of spring chinook at a whopping 68 percent, much higher than either model used in the PATH analysis (BPA's CRiSP model predicted 40 percent, the states' and tribes' FLUSH around 30 percent). But further analysis found some problems with automatic PIT tag data collection at one or two dams, and NMFS has rescinded the 68 percent figure until the situation is straightened out, according to NMFS researcher John Williams. Williams said it looks like survival in the system is about double what it was in the early 1980s, a results of dam passage improvements.

If PIT tag data from birds on Rice Island, where 48,000 detections have been recorded, backs up the trawl data, the PATH process may be in for some serious revision. The weight-of-evidence panel that looked at the competing passage models felt the CRiSP model survival predictions were overly optimistic. They thought FLUSH, which was based on data from the 1970s, fit the empirical data better.

The debate spilled into the public eye at the October IT meeting when BPA consultants and scientists said the evidence panel was given limited information to judge the models. Marmorek's year-end wrap up didn't mention the near mutiny. But the Corps' Doug Arndt alluded to it when he told other IT members that "the split in PATH has severely jeopardized our schedule for the 1999 EIS [on lower Snake dams]."

Corps spokesman Greg Graham announced that the draft EIS will already be a month late, because PATH analyses had been promised by the middle of November. Graham said the delay reduced the probability that the lower Snake feasibility study will be completed by December 1999.

The latest PATH results moved the Sierra Club to say that the only way to save endangered Snake River fish was to remove the four dams. "Nobody is talking about removal of all the dams on the Columbia and Snake rivers," said Bill Arthur, the group's Northwest director. "The biologists are pointing at just these four fish-killers. Elected officials who say otherwise, who pander to the public's worst fears, who demand more analysis and delay, who defend these four dams no matter what, simply invite more political conflict and more dead salmon."

Related Pages:
2017 is Just Around the Corner by Paul VanDevelder, High Country News, 3/23/9
Will We Save Our Salmon? by Ted Kerasote, Sports Afield Magazine, 3/1
Scientific Review Group Says Salmon Could Be Gone by the 21st Century by Francisco & Bakke, NW Fishletter, 5/96

Bill Rudolph
PATH Modelers Announce Year-End Results
NW Fishletter, December 15, 1998

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