When dozens of white sturgeon began washing up dead on the banks of British Columbia's Fraser River in the mid-1990s, some feared that North America's largest freshwater fish could be headed toward extinction.
Once plentiful in the river, the sturgeon population had dropped below 40,000, and scientists were unable to explain the die-offs of mostly female fish.
That's when an alliance of government agencies, environmentalists, aboriginal groups, and commercial and recreational fishers came together to save the sturgeon, spurring a robust recovery of the lower Fraser River population.
Recent estimates show the population has increased to about 50,000 fish.
To Zeb Hogan, who leads National Geographic's Megafishes Project and has studied the sturgeon, it's a rare success story. (Read about the world's gargantuan freshwater fish.)
"Worldwide, most species of large freshwater fish are in danger of going extinct in the near future," said Hogan, a National Geographic emerging explorer. (The National Geographic Society operates National Geographic News.)
"The white sturgeon seems to have avoided the fate of species like the Chinese paddlefish of the Yangtze River and the critically endangered giant catfish of the Mekong River."
But Hogan points out that collaborative conservation programs, such as the one in Canada, would be hard to implement in other parts of the world.
For example "in the Mekong River [in southeast Asia] you have six different countries and their governments, 60 million fishermen, scientists, tourists, all of these different groups," he said.
Healthiest Population
The conservation movement is the brainchild of Rick Hansen, a paraplegic athlete and Canadian national hero who became famous for his 1980s "Man in Motion" tour, during which he traveled around the world by wheelchair.
"There was a lack of knowledge of what was happening with the fish," said Hansen, who founded the Fraser River Sturgeon Conservation Society in 1997.
"We wanted people to volunteer to go out on the river and give them the capacity to tag and then release the fish, and have that volunteer effort be connected to first-class science."
During the conservation effort, the aboriginal peoples of Canada, which call themselves First Nations, ordered a stop to harvest fishing of the sturgeon. Strict catch-and-release regulations for sport fishers were imposed.
A government-research program also led to a volunteer tagging effort of some 35,000 sturgeon—though it's still unknown what caused the die-off.
Today, the lower part of the 870-mile (1,375-kilometer) Fraser River, which flows unimpeded through British Columbia and into the Pacific Ocean at Vancouver, is home to the only white sturgeon population in the world that is entirely wild.
That's because the fish, which are highly migratory, can move and spawn freely throughout their life cycles.
"It's our healthiest population in the province, though it continues to face a lot of pressure from urbanization and habitat degradation," said Steve McAdam, a fisheries biologist with the British Columbia Ministry of Environment in Vancouver.
White sturgeon in three other British Columbia rivers—Columbia, Nechako, and Kootenay—aren't as lucky, and were added to Canada's endangered species list in 2006.
Spectacular Jumps
Among the most dedicated conservation volunteers are recreational fishers.
With commercial fishing banned, sturgeon sport fishing on the Fraser is thriving.
Dating back 200 million years, prehistoric sturgeon are among the largest species of fish on Earth, and are known for their spectacular jumps out of the water when hooked.
There are unconfirmed reports of white sturgeon 20 feet (6.1 meters) in length and weighing more than 1,500 pounds (680 kilograms)—though no fish that large have been caught in the Fraser for decades.
On a rainy Sunday morning this past summer, Megafishes Project leader Hogan was speeding down the Fraser in a boat captained by Fred Helmer, a veteran sturgeon fisher and one of more than 200 guides working in the burgeoning sport-fishing business estimated to be worth U.S. $20 million.
"The sport fishery, which is all catch-and-release, is as good as I've ever seen it," Helmer said.
Sturgeon are bottom dwellers with four barbels—or whisker-like organs—to sense their prey, which is mostly salmon. They have no teeth, and use their vacuum-like mouths to suck up fish.
Anglers capture sturgeon with balls of salmon eggs tied up in panty hose or dead hooligans, members of the smelt family, for bait.
Downstream from the town of Mission, recreational angler Stu Love had caught what turned out to be an 8.5-foot-long (2.7-meter-long) sturgeon weighing close to 300 pounds (136 kilograms).
It took him more than two hours to reel in the beast, which twice jumped completely out of the water.
"It's pretty intimidating to see a fish that big at the end of a rod and reel," Love said.
Helmer scanned the calm sturgeon, a female, to see if it had been previously tagged.
"Nope, it's a virgin capture," he confirmed, before injecting a tiny tag right behind the skull plate of the animal.
After snapping pictures of the giant catch, the fishers released it back into the turbid waters of the Fraser.
Fish Wheels
The sturgeon conservation society has formed a close partnership with aboriginal groups along the Fraser River who are historically and culturally connected to the fish.
"The white sturgeon is almost a god-like sea creature for the First Nations," said Ralph Roberts, who works as the First Nations coordinator for the society.
"They're the ones who put [their] foot down and said this fish has to be protected."
Although First Nations groups are legally entitled to harvest sturgeon, they adhere to a voluntary moratorium, Roberts said.
But each year thousands of white sturgeon are caught—and often killed—accidentally in gill nets deployed by First Nations fishers to intercept salmon migrating upstream.
Encouraged by fisheries-management experts, some are now turning away from gill nets to alternative fishing methods, including the use of fish wheels, which are used to scoop up the fish in a series of baskets that rotate close to the river bottom.
"Nothing is going to be as easy on the fish as a fish wheel," said Karl English, a fisheries biologist working with the society.
"You can take the abundant species and let the rare ones go."