[2] Science Panel Blesses Feds' Passage Model
A panel of independent scientists has reiterated its earlier recommendation for Columbia Basin fish biologists to concentrate on finding out whether fish do better in barges or in the river, instead of trying to quantify latent mortality linked to dam passage.
The Independent Scientific Advisory Board included the recommendation in its June 2 report on the COMPASS model developed by federal agencies to estimate fish survival and compare different hydro operations, including fish barging in NOAA Fisheries' latest hydro BiOp.
COMPASS is the culmination of the analysis of years of PIT-tag survival data that has been collected since the early 1990s.
These data were used first in the BPA-funded CRiSP model developed by the Columbia Basin Research group at the University of Washington. CRiSP eventually won the modeling war with the states' and tribes' FLUSH model, which placed little emphasis on new data and mostly depended on the religious fervor of its practitioners' firm belief in a strong, unproven relationship between river flows and fish survival.
The ISAB has already looked at various facets of the COMPASS model as it was being developed, and has given it a generally favorable review all along. The board's latest words say that the model's "fit to available inriver and hydro-system data is quite good. With a few exceptions, the model has captured the impact of the variables considered. The question of how well the model will work for river conditions encountered in future years must await later data."
Rich Zabel, a NOAA Fisheries researcher and one of the architects of COMPASS, said that "overall," he was pleased with the reviews.
"It offers constructive criticism but does not indicate the need for a model overhaul," he said, "We should be able to address all the concerns raised by ISAB."
In fact, the ISAB specifically said the COMPASS model "strikes a healthy balance between simplicity and realism." It said the model must serve myriad purposes, "and we find ourselves calling for more detail at various points, while constantly reminding the team to 'keep it as simple as possible.'" The feds had pointed out other confounding factors.
A COMPASS analysis is also the basis for the new BiOp's call to maximize fish barging from lower Snake dams in early May to boost survival of ESA-listed steelhead over the current court-ordered operation. The feds' computerized crystal ball says the change would boost steelhead returns by 18 percent over BiOp judge James Redden's temporary prescription.
In its latest report, the ISAB echoed its earlier findings in a report released more than a year ago, saying it was "somewhat pointless" to quantify latent mortality, given the absence of reliable data for fish survival below Bonneville Dam, and a general lack of comparable data from the period before the dams were built.
Latent mortality is a hypothesis born in the 1990s from a testy collaboration of state, tribal and federal scientists called PATH (Plan for Testing Hypotheses) that basically says young fish die eventually at higher rates after they have passed dams than fish which have no dams to contend with--and fish that are barged have even higher rates of mortality than those migrating inriver.
However, the ISAB did say it was time to separate survival data of transported fish at each dam where they are collected, because it seemed to make a difference.
For years, state, tribal and some USFWS scientists have argued that upstream/downstream comparisons of fish survival proved that latent mortality is a good reason to breach lower Snake dams.
In their latest analysis, presented before the ISAB in late 2006, members of this group told the panel that latent mortality for the Snake spring chinook was in the 60-percent range, based on comparisons with downriver stocks from the John Day River, and that accumulated stress from passing those four dams on the Snake was the primary cause.
But in its 2007 review, the ISAB took issue with the states and tribes for using reconstituted stock recruitment "data," confounding effects from innate biological differences in upstream and downstream stocks.
The feds had pointed out other confounding factors, including the likelihood that barged fish were, on average, smaller than inriver fish since they were more easily guided to bypass routes at the dams where fish were collected. They also said differences in the timing of ocean entry played a role in their ultimate survival.
Another hypothesis presented by NMFS scientists Mark Sheuerell and Zabel suggested that the difference between post-Bonneville Dam smolt-to-adult returns is a function of arrival time below the last dam, and a year-effect. Earlier arriving fish survive better, they say.
But that hasn't stopped state and tribal biologists from wanting to expand their old upstream/downstream analysis--this time to fall chinook. In a nod to the Corps of Engineers, state and tribal parties to the U.S. v. Oregon process have OK'd, for this year only, a reorganization of priorities that allows the use of fall chinook hatchery fish to be raised as wild fish "surrogates" for an important 5-year-long Corps transportation study.
But the U.S. v. Oregon parties added a big footnote to their approval. They want the Corps to tag downstream fall chinook from Hanford Reach, the Deschutes River, and the Little White Salmon Hatchery beginning next year as part of the study. If the Corps doesn't agree, the parties will bump the transport fish from 6th on the production priority list down to 12th and 14th.
The Corps wouldn't agree to tag downriver fish this year, and they don't plan to next year, for the same reasons the ISAB had raised about spring chinook, said Corps biologist Rock Peters. But he also noted that it is an issue likely to be visited by all parties again next year.
Others say the biological differences between upriver and downriver fall chinook stocks are even greater than those between spring chinook. One major difference is the large share of upriver Snake fish that hold over in the basin until the following spring, unlike downriver stocks that have a tiny overwintering component. -B. R.
The following links were mentioned in this story:
Review of the Comprehensive Passage (COMPASS) Model – Version 1.1
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