Salmon fry dart through the river at Goldstream Park where a gasoline spill has put the salmon hatchery in jeopardy.Arnold Lim for The Globe and Mail
For generations of Victoria schoolchildren, the rich ecosystem of Goldstream Provincial Park has served as an outdoor classroom where students learn about the lifecycle of West Coast salmon in a pristine natural setting.
This spring, children involved in the park's "great fry escape" program are also learning some sobering lessons about the dangers of impaired driving and the deadly effects of toxic spills on fish-bearing streams.
Last month, hundreds of children who had raised salmon fry in their classrooms over the winter were unable to release the fish into the Goldstream River after a fuel tanker overturned in the park, spilling 42,000 litres of gasoline into the river.
Police suspect the truck's driver had been drinking.
Parks staff considered cancelling the great fry escape altogether, but instead decided to use the incident as a teaching tool.
"Unfortunately, the schools were not allowed to release their fry so we had to adjust the program," said Allison Roberts, a naturalist at the Goldstream Nature House. "We're letting the kids know exactly what happened because they're the ones that are going to be making decisions about our salmon in their future."
On Friday, a class of about 20 Grade 3 students from Hillcrest Elementary School set their salmon free in a creek on the other side of town, then travelled to Goldstream Park to study the river's fish habitat.
"I felt really sad that we had to release our salmon somewhere else because they were born here and Goldstream River is their home," said nine-year-old Ethan Wareham.
Students in the fry escape program are asked to test the river's pH level, check the water temperature and collect bugs to ensure their fish are being released into a healthy environment.
But on Friday, test strips dipped into one pool of water indicated a pH level of 5 - far too acidic for salmon fry, which require a pH level around 8. The children also learned that large numbers of aquatic insects had been killed by the spill and that scientists are concerned the salmon won't have enough food.
The class's experiments mirrored the real-life environmental monitoring taking place elsewhere in the park on Friday.
Absorbent booms resembling long paper towel rolls remained stretched across the river every 50 metres or so, from the site of the crash to the mouth of Finlayson Arm more than a kilometre away. In a handful of places, pockets of foam tinged with shiny brown streaks of petroleum gathered along the booms.
Farther upstream, contractors hired by Columbia Fuels, the company that owned the truck, collected water, soil and sediment samples from the riverbed.
Graham Knox, manager of environmental emergencies for the B.C. Ministry of Environment, said the spill occurred at a critical time, just as chum salmon fry were emerging from eggs deposited during spawning season last fall.
"We believe that about half of the spawn was still in the riverbed and they've been emerging through this time," he said. "One of the good things is, we have seen evidence of new fish emerging."
This year's coho fry will begin emerging in the next few weeks, but it's too soon to tell if they will be affected, he said.
Work crews have removed between 30 and 40 truckloads of contaminated soil from the area, but experts feel that any more digging would release toxic hydrocarbons that remain trapped in the river sediment, Mr. Knox said.
The April 17 fuel spill killed thousands of adult fish, along with an estimated 8,000 coho fry that the Goldstream Fish Hatchery had just released, said park naturalist Tracey Bleackley.
The full effects, she added, won't be known until this year's salmon return to their spawning beds in the Goldstream River in four or five years.
Special to The Globe and Mail