For the first time in a century an endangered Atlantic Whitefish made it back over a dam near Bridgewater to spawn - thanks to a newly opened fishway costing $800,000.

"It was pretty exciting," researcher Erika Cross tells CBC News.

The world's surviving wild population of Atlantic Whitefish - believed to number only a few hundred - have been landlocked in three lakes that serve as the water supply for the town of Bridgewater NS. They have been trapped there by a dam.

"We're hoping this fish might be the start of a whitefish run," said Cross, who works with the Bluenose Coastal Action Foundation.

On Oct. 21 Cross found a 31 centimetre Whitefish in the fishway as it was trying to make it back up over the dam to spawn. DNA tests will determine its age and whether the fish has been in saltwater. Like its relative the salmon, Atlantic Whitefish are naturally anadramous, meaning they travel in both salt and fresh water.

"My thought is that it's a fish that fell over the dam and not one released as part of an experiment a few years ago," said DFO scientist Rod Bradford.

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This new fishway is helping the fish to spawn. (CBC)

The fish caught this week did not have a clipped fin or a dye used to identify hatchery bred Atlantic Whitefish.

Bradford heads up the federal fisheries recovery effort for the species. He says for decades, Atlantic Whitefish have been consistently reported below the dam in the Petite Riviere system but there's never been a way back until the fish ladder was built next to the dam.

"There's never been any demonstration of an anadromous run for a very long time. The thinking has been these are fish that have been essentially lost to the population," said Bradford. "Now they're not lost."

Success at the fishway comes after the Harper Government decided to close a nearby federal hatchery that generated broodstock for the Atlantic Whitefish. The captive breeding program at the Mersey Centre will close in 2014. Earlier this year, federal Fisheries Minister Keith Ashfield said stocking a lake in Dartmouth with Atlantic Whitefish addressed that issue.

Researchers and scientists say the fishway offers hope for a species whose entire world can be covered in a 30 minute drive around the lakes. The prospect of re-establishing an Atlantic Whitefish run to the ocean and back is now in sight.

"Fish that travel to the ocean are bigger, more robust. Bigger fish produce more eggs," said Cross. "So if we get bigger fish up in the lakes producing more eggs that can probably help with the recovery of the species."