The story of the demise of America's largest freshwater fish reads much like that of the Snake River's more celebrated denizens, the chinook and sockeye salmon. Dams, pollution, irrigation withdrawals and heavy harvests have taken a steady toll on the bottom-dwelling sturgeon, which are thought to live as long as a century.
In 1943, the state banned commercial white sturgeon fishing on the Snake River, and since 1970, sturgeon can only be caught on a catch-and-release basis. Last year the state began requiring the use of barbless hooks.
State biologists say water withdrawals for agriculture combined with nutrient-loaded runoff from farms, fish hatcheries and municipalities, continue to have a major impact on sturgeon. Bob Horton, a fish biologist with the Idaho Fish and Game Department, says a combination of such factors turned the Brownlee Reservoir into an oxygen-depleted stew in the summer of 1990, killing at least 30 of the fish.
But dams remain the biggest threat, most fish experts agree. Dams have divided a river population into nine isolated subpopulations and kept the wide-ranging species from its occasional forays into the Pacific Ocean for food.
Only two of the nine sturgeon populations - the one below Hells Canyon Dam and the one between C.J. Strike Dam and Bliss Dam - are healthy and viable, says Tim Cochnauer, an Idaho Fish and Game fish manager for the Clearwater Region. "There certainly are concerns about the other populations. There are red flags that indicate those populations are barely holding their own."
The dams have greatly reduced the amount of spawning habitat for the sturgeon, says Charles Ray, Idaho Rivers United's salmon coordinator. "Over 50 percent of the river is now impounded," he says. "Sturgeon won't spawn successfully in reservoirs, they need a free-flowing river."
By isolating different populations, the dams have also reduced the fish's genetic variability. Cochnauer says, "The only movement that we would expect to occur between populations is downstream movement. That would be during high water times of the year when fish are spilled over the dams."
Upstream movement is nonexistent because of the dams, adds Cochnauer, even though some built around 1950 had fish ladders. "(These ladders) were not constructed to meet the demands of sturgeon," he says. Dams constructed later - Brownlee, Oxbow and Hells Canyon - were built without fish ladders, he adds.
The federal relicensing of three of the dams may provide fish advocates with an opportunity to correct the mistakes of the past. The Federal Energy Relicensing Commission will consider relicensing Idaho Power's Bliss, Upper Salmon and C.J. Strike dams in 1998, 1999 and 2000, respectively. Conservationists say they will press FERC to force the utility to release more water during the spring spawning season.
In response to the upcoming relicensing, the company has been conducting white sturgeon studies on the middle Snake River since 1991. The studies are looking at the status of sturgeon populations and how the dams are affecting them, says Ken Lepla, an Idaho Power fish biologist. The data collected will remain proprietary information until licenses are secured, he says, although some information is being shared with Idaho Fish and Game and the U.S. Fish and Wildlife Service.
The state is currently investigating the possibility of using hatchery fish to enhance or supplement Snake River white sturgeon. Since 1989 an experimental program has planted marked juvenile sturgeon on different segments on the Snake River where their growth and survival rates are being monitored.
Both Horton and Cochnauer believe that fishing had an impact on the white sturgeon population before the dams were built. "We believe there was probably some overharvesting of the big fish," Cochnauer said. "There weren't very many (to begin with). They were the ones people liked to catch and they were the ones photographed a lot."
For fishermen like Charles Ray, catching a sturgeon is like traveling back in time. "Every time I hook one I wonder how many times this fish saw the Pacific Ocean, or how many times it migrated in and out of Hells Canyon before the dams were built."
* John Rosapepe
The writer free-lances from Portland, Oregon.