Nova Scotia's Kejimkujik National Park welcomes 40,000 visitors a year, but there is one visitor Parks Canada desperately wants to keep out: invasive fish that are now established just outside the park boundary.
Over the next three years Parks Canada will spend $797,000 to try to stop invasive small mouth bass and chain pickerel from getting into the park. It's the last large watershed in southern Nova Scotia still free of the predators.
Nearly 50 per cent of Nova Scotia's watersheds now contain one or both of the invasive species. "We take invasive species seriously," says park superintendent Jonathan Sheppard.
If they do get in, Parks Canada believes it can stop them from spreading by building a barrier at Peskowesk Brook, an isolated choke point deep inside the park.
The barrier would seal off about 30 per cent of the Keji watershed.
Fending off Cannon Lake population
"Part of the reason we are embarking on this project is we feel ... we're well-positioned to make some real progress to prevent the spread," said Sheppard.
The most immediate threat is from small mouth bass in Cannon Lake, just two kilometres outside the park. The lake is connected to the park by a brook blocked only by a large beaver dam.
The Nova Scotia Department of Fisheries and Aquaculture has helped by deploying its electro-fishing boat to the lake. The boat shoots electric current into the water, stunning fish as it passes. Since 2014, electro-fishing has removed 301 of the invasive fish from Cannon Lake.
Over three years, the number of bass caught per hour has been falling, implying a reduction in abundance.
"We intend to go back this year," says Jason Leblanc, who manages the boat.
Part of the Parks Canada response includes monitoring by its staff and volunteers. The good news so far is there have been no confirmed sightings of small mouth bass inside the park.
Brook trout population thriving in Keji
Ironically, the threat comes as the park's native brook trout is at its healthiest level in 30 years, as measured by population, size of adults and other metrics.
Local author and veteran angler Reg Baird has fished in Keji since 1949.
"There's very few places left in Nova Scotia where brook trout are thriving without some help of stocking, but these are all wild trout," says Baird, who has been a research volunteer at Keji for years.
"The whole brook trout fishery at Keji National Park is at stake if we have invasive species come in, there's no doubt about that."
He has no time for anglers who are spreading the invasives by moving them from lake to lake in a bucket.
"They are creating a disaster when they do stock bass or chain pickerel in a system where the brook trout thrive. Everything goes downhill from there."