Biologists hoping redesigned dams will spur endangered eel's return to Ottawa River

Biologists hoping redesigned dams will spur endangered eel's return to Ottawa River

Eels were once the most plentiful fish in the Ottawa River, but they've become endangered because of dams, so biologists are working on ways to provide them safe passage in an effort to boost their numbers.

"It was the most common fish in the Ottawa River. Probably 50 per cent of the fish in the Ottawa River were once eels," Canadian Wildlife Federation senior conservation biologist Nick Lapointe told host Hallie Cotnam on CBC Radio's Ottawa Morning on Monday.

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But now eels account for less than one per cent of the river ecosystem, and he says hydro dams are to blame for hindering their movement along the river.

"When you have barriers to that movement — the Ottawa River has I think 12 dams on the main stem, plus many other dams on all the tributaries — that blocks the juvenile eels from getting upstream," said Lapointe. 

"And unfortunately in the turbines, when you have a big long eel trying to migrate downstream, it has to go through the turbines in most cases. And that's a really big risk of getting chopped up."

Now, 80 per cent of fish in the Ottawa River are channel catfish, while the eel languishes, unable to pass through turbine blades safely.

"Anytime that you have a species that was once the most common in the ecosystem become virtually obliterated from that ecosystem, that's really a problem," he said.

New turbines

The Canadian Wildlife Federation has been working with Energy Ottawa to create a safe eel passage through dams on the Ottawa River, including the one at the Chaudière Falls.

"Energy Ottawa is putting a new set of turbines in place," said Lapointe. 

"They're renovating one of the previous sets, and they're putting a screen in place to keep eels from going down through the turbines as they out-migrate, and giving them sort of bypass channels — safe passage channels — [as] a detour that they can go around the turbines."

Lapointe's team will also be working over the summer to put transmitters in eels to track their movement and gauge the impact of these new dam passages. 

The health of eels in the Ottawa River also directly impacts the commercial fishery in Atlantic Canada, so Lapointe believe it's crucial to get stocks back up here at home.

"When you have the most abundant species — to have that lost, there are potential implications for the resiliency of the ecosystem," he said.

"So to now to have this ecosystem that's so dominated by [catfish] isn't necessarily in the healthiest of states."