[4] Latest Research Strongly Supports Fish Barging Effort

Barging wild spring chinook from Lower Granite Dam was about 500 percent more effective than leaving the fish in the river, according to federal scientists who added up adult salmon survivals from the 2004 outmigration.

They said wild steelhead showed about a 250-percent survival improvement from barging.

The results were presented at the annual Corps of Engineers' research review, held Dec. 3-6 in Walla Walla.

NMFS scientist Doug Marsh, who presented the latest fish transportation analysis, told NW Fishletter that his results may be biased somewhat towards barging because the analysts were forced to combine juvenile groups using different inriver passage routes in order to improve statistical rigor because so few adults returned.

In fact, no adult wild springers were counted that were not detected as smolts, which means they passed all four Snake dams via spillway or turbine as juveniles.

Marsh said the overall ratio of transported to inriver SARs [smolt-to-adult returns] was 4.8:1.

In 2006, adult returns to Lower Granite Dam were small as well--only two dozen in the case of the barged spring chinook--but they outperformed inriver migrating (non-detected) chinook by 2.64 to 1.00.

Barging was effective for wild steelhead as well, with the ratio of transported to inriver at 2.5:1. Marsh's 2006 results were nothing short of spectacular. They outperformed non-detected inriver migrators by 800 percent.

Other findings on the barging front included the latest results from a study headed by F.J. Loge of the University of California at Davis.

The study investigated effects of disease on barged and inriver smolts by putting fish from each category in net pens in the estuary below Bonneville Dam to see how they fared. The study found that barged fish from Idaho's Dworshak Hatchery (Clearwater River) had significantly greater mortality than transported fish from the Rapid River Hatchery (Snake River).

The study concluded that the differential delayed mortality of barged fish was mainly due to the health status of the fish when they entered barges at one of the lower Snake dams, and not necessarily from the barge conditions themselves.

"Once the differential delayed mortality is expressed in the estuary by the natural culling of unhealthy fish," they reported, "the remaining barged fish are healthier than fish with an inriver life history."

These results could affect the debate with fish advocates, who say barging doesn't work.

Other scientists, led by researchers from NOAA Fisheries and Battelle, said their preliminary results of extensive acoustic-tagging studies are showing somewhat better estuary survival than their previous two years' results when they estimated spring smolt survival from Bonneville Dam to the ocean between 60 and 85 percent.

Previous findings also found that about 80 percent of the little springers made the journey from Lower Granite Dam to the mouth of the Snake and, around 40 percent make it all the way downriver to the ocean.

Canadian researcher David Welch said his 2007 results were similar to his 2006 results. Using acoustic tags that are larger than the Corps' version and longer-lasting, Welch has followed small groups of both barged and inriver migrating fish past the mouth of the Columbia to detection arrays off the Washington coast and the northern tip of Vancouver island. Survival of Yakima and Snake River smolts were reported to be nearly identical to the 2006 results, but higher for the Snake River fish "when migration distance was taken into account."

Welch found that the survival of transported smolts between Bonneville Dam and Willapa Bay was equal to or greater than the inriver smolts--"indicating transportation did not reduce survival."

His initial findings showed about 20 percent of both the Snake and Yakima inriver migrating fish made it to the first ocean array off Willapa Bay. About 5 percent of the Snake fish and 2.5 percent of the Yakima fish were detected off Vancouver Island. -B. R.

The following links were mentioned in this story:

The Anadromous Fish Evaluation Program 2007 Annual Review

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