Volunteers at a fish hatchery on the Coquitlam River are devastated after something killed 15,000 coho fry in their tanks last month.
A spokesperson for the Port Coquitlam Hunting and Fishing Club, which runs the Al Grist Memorial Hatchery and has been raising coho and chinook fry on the river for 30 years, said a new water line was being connected upstream from construction of a new $110-million ultraviolet disinfection plant at the Coquitlam reservoir when the fish kill occurred.
The raw water from the Coquitlam reservoir that feeds the tanks was diverted into the new line and tests conducted by Metro Vancouver have ruled out water contamination from organic materials and metals.
The group suspects the fish kill was caused by an increase in the total dissolved gas saturation, which can occur when water spills over a dam or waterfall, and is not dangerous to humans but is deadly to fish.
"It forms air embolisms in the blood stream, the circulation is blocked and they die," said hatchery volunteer Norm Fletcher. Higher than usual water temperatures for the time of year could also be a factor and his group is anxious to get more information before it starts collecting eggs from brood stock in November. And they hope Fisheries and Oceans Canada will come up with some answers so it doesn't happen again.
A Metro Vancouver spokesperson said extensive water quality studies were conducted, including testing for organics and metals, but no problems were detected. "We couldn't detect anything of a chemical nature," said Rick Galley, who works in the operations and maintenance department.
Supersaturation is not a test the government agency does because it isn't a drinking water issue but Galley said every effort was made to isolate the hatchery from construction at the new water treatment plant and make sure the pipes were clean before reconnecting the pipes.
As soon as a problem was detected, the water was shut off and a testing regime was implemented. "We did a bio-assay, which is testing in a laboratory environment with fish, and did some metal sampling, which we don't really do on raw water and couldn't find anything.
"We're working with the hatchery, they are carrying on with investigations," he added.
Club volunteers flushed out water lines, along with Metro Vancouver, before the new pipe was connected to Metro Vancouver's main line.
It takes thousands of hours of volunteer work to maintain the hatchery and raise and release fish fry, Fletcher said, and hatchery workers are upset that a year's work was lost during the fish kill but they aren't giving up and are prepared to get on with the job of raising fish for next year.
"There's nothing you can do about the loss, other than get ready for next time," he said.
The group typically collects about 30,000 coho eggs, as well as chinook, which don't overwinter at the hatchery. About half the coho are released to restock the Coquitlam River; the remainder are raised in tanks until they reach a length of about 2.5 to 3 inches, which enhances their chance for survival. In June, after their adipose fins are clipped, they are released and returning coho, fully grown from their journey out to sea, can be caught by sports fishermen.
