The Whitehorse Rapids Salmon Hatchery is a kind of insurance policy. No one knows for sure whether the chinook salmon stocks of the upper Yukon River valley could survive the stresses of the Whitehorse Rapids dam without help from the hatchery. But as long as the hatchery is there, no one will need to find out.

The hatchery is funded by Yukon Energy, Yukon Renewable Resources, Yukon Tourism, and a British Columbia company called Creative Salmon. It is operated by the Yukon Fish and Game Association.

For millennia, salmon have spawned in streams like Wolf Creek and Michie Creek, above the Whitehorse Rapids. Even before a hydroelectric dam was built at the rapids, the fish faced an overwhelming struggle for survival.

"This run of fish is unique," says Lawrence Vano, manager of the Whitehorse Rapids Salmon Hatchery. "It's the longest chinook migration in the world. They travel 1800 miles up the river to spawn."

When juvenile salmon head down the river in the spring, they face predators all along their route. First, they have to pass through "pike-ridden" Marsh Lake, Vano says. Then comes the upper Yukon, with grayling, mergansers, seagulls, and more pike eager for a meal of juvenile salmon.

And, as if natural hazards weren't enough, they then face the Whitehorse Rapids dam.

"They've got to go through those turbines, over that spillway, or through the fish ladder, whichever sucks them in," says Vano. Although it's difficult to measure the survival rate, Vano says an estimated 20 to 30 percent of the salmon perish in the turbines. Those who survive still have a long and perilous journey through Lake Laberge and down the entire length of the Yukon River.

"Anything that could eat them on the way down is going to be just feasting," Vano says.

Those who reach the ocean spend four years evading killer whales, seals, and fishing nets. Then they fight their way back up the dangerous river to spawn, past the river fisheries, the predators, and the fish ladder.

"And past me, because I'm taking brood stock," says Vano.

Scientists estimate that for every five thousand salmon eggs laid in the gravel in nature, only six salmon return as adults. Vano thinks that estimate is optimistic for the strenuous Yukon chinook run.

"That's why I'm really thrilled each year to see the fish come back."

Some of the fish are old friends. Every year, in long vats in the salmon hatchery, Vano raises thousands of tiny salmon for release into spawning streams above the dam.

Before they are released, they are marked. Vano and his colleagues clip a dorsal fin and insert a tiny tag into the fish's nose. The clipped fin identifies the fish as hatchery-reared, and the tag identifies the stream it was released into. The federal Department of Fisheries and Oceans foots the bill for the tagging program.

Each summer, Vano harvests up to 30 percent of the fish passing through the Whitehorse fish ladder to provide spawning stock for the next year's juveniles. He avoids fish with clipped fins that indicate they are hatchery fish, and takes eggs and sperm from the wild stock to vary the genetic mix of fish in the hatchery program.

Since genetic diversity tends to make a species more resilient, Vano broadens the genetic mix even further by "matrix spawning." He divides the thousands of eggs harvested from a single female into several batches and combines each batch with sperm from a different male.

The hatchery program appears to be working. The past three summers have seen steadily increasing runs of chinook passing through the Whitehorse fish ladder. Last year 3,000 salmon reached the fish ladder -- and 40,000 tourists.

Vano enjoys the reactions of the tourists. One man from Ireland started crying when he saw the fish. He remembered seeing fish coming up a river in Ireland when he was a boy, he told Vano, but pollution had driven them all away.

"Just to see people's eyes when they get off the tour bus is wonderful," says Vano. "You can see why I consider this to be a very important run of fish."

For more information about the Whitehorse Rapids Salmon Hatchery, contact the hatchery at 668-3938.