N.S. fishway created to save endangered species

Researchers in Nova Scotia are hoping a new $700,000 fish ladder outside Bridgewater will help an endangered and landlocked fish species escape to the sea and escape extinction.

The world's only surviving population of Atlantic whitefish is confined to three lakes that make up the water supply for the town, part of the South Shore region of Nova Scotia.

"It's a pretty rare and unique species," said Erika Cross, a researcher with the Bluenose Coastal Action Foundation.

Cross estimates between 500 and 2,000 surviving adult Atlantic whitefish are stranded behind a dam first built in the 1890s. The exact population of the fish — which have not been able to reach the ocean in more than 100 years — is not known.

"What I'd like to see is the fish returning to their natural state. I'd like to see the fish expanding to other regions and having a broader range of habitat and also learning a little bit more," Cross told CBC News.

"There are some pretty significant knowledge gaps with this species and I guess what we're trying to do is just learn a little bit more about its life history."

This week, the town of Bridgewater — which owns the dam — and Fisheries and Oceans Canada commissioned a $700,000 fishway that will open a route back from the sea for the first time in decades.

Fisheries and Oceans Canada declined to speak about the project.

"With the opening of this fishway, that allows the fish to travel between the sea and their spawning grounds, which are up above the dam," said Cross.

Last month, the Bluenose Coastal Action Foundation installed a rotary fish trap downstream from the dam to capture any Atlantic whitefish that may try to run to the ocean. So far, none have been captured.

'They could start running immediately'

The key question researchers are trying to answer is whether the Atlantic whitefish has retained its anadromy, or its genetic memory to run to the ocean.

"They could start running immediately or it could take a few years. We're really just not sure yet," said Cross.

Cross said recent physiological tests on the offspring of broodstock taken from the lakes have shown a tolerance and even a preference for seawater at a certain age.

She called that an encouraging sign, because the fish have access to a more abundant food supply. Ocean-run fish tend to be bigger and more robust, said Cross.

But, the Atlantic whitefish may need to bulk up if it's to survive. It's threatened by the smallmouth bass, a species that was likely introduced into the watershed by anglers in the 1990s.

"They may be eating the whitefish outright or they could be a competitor for resources," said Cross.

The fish ladder is expected to open in late May.

Bill McInnis, a Bridgewater councillor and chair of the Public Service Commission, said given the stakes involved, the fish ladder is money well spent.

"We talk about cost. Is there a price for saving a species? I think it's a small price if you're going to save a species from leaving our planet," he said.