the film forum library tutorial contact

Study that says Snake Dams Don't Stifle Fish Survival Knocked by Erik Robinson The Columbian, July 6, 2009

New research suggests that ocean-bound salmon forced to pass eight dams -- including four on the lower Snake River -- appear to fare no worse early in their life at sea than salmon crossing only four dams on the Columbia River.

The lead researcher said the study bolsters the case for leaving the Snake River dams in place.

"The farther out from Bonneville, and therefore the later in time, the more tenuous becomes the argument that the Snake River dams are causing the poor survival of Snake River salmon," said David Welch, president of Kintama Research Corp. in Nanaimo, B.C.

However, other fishery scientists strongly criticized the report as severely lacking in scientific rigor. Similar criticism dogged a study last year in which Welch found comparable survival rates for fish migrating the dammed Columbia and the undammed Fraser River in Canada.

"The problems and limitations of these Welch analyses are so extensive as to be pretty much unusable," said Michele DeHart, director of the Fish Passage Center in Portland.

"They've drawn some pretty strong conclusions prematurely from only one year of data," added Howard Schaller, project leader of the Columbia River fisheries office for the U.S. Fish & Wildlife Service in Vancouver.

Welch argues that his latest research, while not flawless, marks a milestone as the first direct detection of salmon smolts in the ocean.

The Pacific Ocean Shelf Tracking project is made of a series of acoustic receivers 700 feet below the ocean surface. Tethered to anchors running out from the coast to the continental shelf, the lineup of sensors is designed to detect acoustic tags implanted in fish. Welch's team installed a half-dozen arrays from the Columbia River all the way to southeast Alaska in an effort to better understand what happens to fish in the ocean.

The Northwest Power and Conservation Council steered $3.6 million to the project over the past three years. The money comes from electric rates paid to the Bonneville Power Administration.

Salmon-friendly improvements at the dams over recent years has reduced the number of ocean-bound juveniles killed as they pass over spillways or dive through turbines. Yet the proportion of Snake River wild and hatchery-raised juveniles that return to the river as adults is generally lower than salmon populations that don't have to pass as many dams.

Scientists theorized that juveniles exhausted by the long outward migration through the stair-stepping reservoirs may suffer from delayed mortality; that is, the journey downriver doesn't kill the fish, but makes it more difficult for them to survive long enough to return to spawn.

Welch wanted to test the theory.

Researchers measured two groups of fish in 2006. They inserted acoustic tags in a total of 794 spring chinook raised in hatcheries, half from the Yakima River basin and half from the Snake River in Idaho. Then they waited.

Ultimately, a little more than 100 in each group -- roughly a quarter -- were detected along a line of 40 ocean-floor sensors running 18½ miles out to the continental shelf from Willapa Bay.

"This is the first time anybody's ever done this," Welch said. "Most people thought that we couldn't make it work, period. It's not flawless. But it's pretty darn good for a first try, and now we know how to make it even better."

The study acknowledged that the proportion of Snake River spring chinook returning to spawn as adults is only about a fifth of the Yakima River spring chinook. Something is killing more of the Snake River fish, but Welch argues it may be attributable to different migration patterns within the ocean.

"Most salmon biologists, because of their freshwater training, assume the ocean is homogenous and pretty stable over time," he said. "But neither of those assumptions is true."

The results, published last week as a "rapid communication" in the Canadian Journal of Fisheries and Aquatic Sciences, has already engendered a backlash from several scientists involved with Columbia basin salmon issues.

They note that the study relied on a miniscule sample size, the fish were released at different times, and the study assumes both groups were detected equally in the ocean. Further, the relatively large size of the transmitters forced researchers to skew the study toward larger smolts that may not be representative of imperiled wild-spawning salmon. At about 8 percent of the fish's body weight, DeHart described it as roughly the equivalent of a human swallowing a scuba tank.

The findings come at a critical juncture.

Environmental groups, joined by the Nez Perce tribe and the state of Oregon, are suing over the federal government's latest plan to balance hydropower dams against endangered salmon in the Columbia River basin. Several other Columbia basin tribes, along with the states of Washington, Idaho and Montana, support the plan issued in 2008.

The Obama administration has asked for another month to consider whether to defend the plan as its own.

The Northwest Power and Conservation Council, which distributes about $140 million annually in BPA ratepayer dollars, bankrolled the Welch study because it holds promise for tracking salmon in the ocean, spokesman John Harrison said.

Related Pages:
Salmon Delayed Mortality Happens Farther Out in Ocean by Rocky Barker, Idaho Statesman, 6/30/9
Salmon Salvation by Ken Olsen, High Country News, 5/4/9