The Nechako white sturgeon, the largest freshwater fish in Canada, is a survivor from the age of dinosaurs.
It’s likely that these giants, that can grow to more than 300 pounds and eight feet in length, arrived to the Nechako watershed more than 10,000 years ago form the Upper Columbia River, when the two water systems were connected during the last ice age.
And although, at one time, the species was so plentiful that reports from the Hudson Bay Company in the 1800’s speak of an abundance of sturgeon being caught by anglers, the most recent estimates suggest that there are only about 600 of the fish left.
Wayne Salewski, the volunteer chair of the Nechako White Sturgeon Recovery Initiative, is a passionate advocate for the initiative and explained that the work being done in the town of Vanderhoof is all that stands between the sturgeon and extinction.
“The sturgeon are SARA (Species at Risk Act) listed,” said Salewski.
“Under the Species at Risk Act you have a number of designations. You have yellow-listed, blue-listed, red-listed and then you have SARA listed. Beyond that you have extinction – dinosaurs, ivory billed woodpeckers, carrier pigeons and other species that the world will never see again. We are that close to losing these magnificent fish forever.”
According to Salewski, the problem is most likely linked to the existence of the dam on the Nechako river.
“Everywhere in the world where you have a dam on a river, you see the same kind of situation develop with fish species,” he said.
And while the exact correlation between the dam and the fish decline is not yet certain, there are a number of indicators about what the problems might be.
Water levels and the fluctuating water temperatures in the river are commonly thought to be at the heart of the situation according to many community residents, but the more serious culprit may be silt.
“Because you don’t have a normal flow in the river, the crevasses and irregularities on the river bottom have been silted over,” said Salewski.
“You go to the river bottom and it’s as smooth and hard as a linoleum floor. When the sturgeon deposit their eggs, instead of adhering to crevices, sunken logs and rocks, they just bounce along until they have been coated so heavily with silt that they can’t hatch. As well, the longer they bounce, the more vulnerable they are to predators.”
To address that situation, the Centre has experimented with constructing new spawning beds, using a barge to deposit rocks in the traditional spawning areas, and periodically lifting and “fluffing” the sediment off those rocks.
But the main initiative of the Centre involves harvesting eggs from mature female sturgeon and, with the assistance of volunteers, mixing the “milk” from mature male sturgeon (which is unceremoniously extracted with a plunger) to fertilize the eggs.
The hatchling’s are then raised in tanks in the Centre’s high tech facility until they are about two years of age.
During that time they are weighed, measured tagged with “pit tags” and radio telemetry, and raised to a size with the best chance for survival in the wild.At that point they are taken to the river in early May and, again with the help of volunteers, are released into the river at about nine separate locations.
And despite the high tech approach to the process there is still not a good understanding of how many fish need to be raised in this way to give the species a chance at survival.
“That’s really something we’re still studying,” said Mike Manky, one of the two full time staff at the facility.
“It’ll take a number of years to study the survival rates. We have a SARA permit to raise up to 12,000 fish a year, but we are being cautious not to over populate the river basin with young fish and have been releasing about 5,000 a year.”
From that number, Manky estimates that only a tiny fraction of the fish will reach sexual maturity (25 years old for males and 45 for females).
“We lose a lot to predation by otters, osprey, seagulls and other animals, and it takes a long time to study how many fish we have to release to rebuild the natural population.”
But for Salewski, the effort is worth it.
“What is saving a species worth?,” he asked.
“We are literally saving the DNA of this species so they don’t disappear from the planet.”
Salewski’s first encounter with the sturgeon came back in the 1970’s when, thrilled at having caught a large sturgeon, he was hosting a barbecue for friends where the fish was consumed. It was then that he was told that the fish he had caught was more than 65 years old. Someone had “counted the rings” on the fish and determined it was born in 1917.
“I had an epiphany that day. I knew we had no business destroying these creatures for what?… a few hours of feasting? It was just wrong.”
It’s a message that the Centre promotes to the thousands of tourists and school children that annually tour their Vanderhoof facility, and it’s a message that Salewski hopes will have a long term impact.