'Like a bad dream': Parks Canada fights back against invasive species in Keji

An unwelcome visitor has made its first appearance of the season at Kejimkujik National Park and National Historic Site in southern Nova Scotia.

"It's a feisty one," Scott Lugar, a resource conservation technician, said recently as he pulled an invasive chain pickerel from a net trap installed in hip-deep water along a shoreline.

From a single chain pickerel captured less than a year ago, the voracious predator has now spread throughout the entire park.

"It's kind of like a bad dream and it just keeps getting worse," said Chris McCarthy, a Parks Canada resources manager.

Once established in a water system, chain pickerel quickly take over. They eat everything they can — other fish, reptiles, frogs, dragonflies, even ducklings.

That is bad news for brook trout — the king of fish in Kejimkujik — and species at risk in the park, like the Blanding's turtle, which is endangered, and the eastern ribbon snake, which is listed as threatened. Both venture into shoreline water.

Exactly how or where the chain pickerel got in is not known. It may have been through a river or stream on the southern side of the park.

Parks Canada had been focused on another invasive species in the area, smallmouth bass, which is established in a lake just outside the Keji boundary.

Managers had developed plans to prevent the chain pickerel from entering Kejimkujik, but were too late. Once inside, the spread of chain pickerel has been surprisingly swift.

"It really was an explosion," said McCarthy.

"We didn't see any sign of them at all. There were unconfirmed reports from other fishermen but we never had pickerel in hand until last year. And now all of a sudden they're everywhere. So I guess the warning is that if you get them in your system it's going to happen quickly."

The question is what next

"It's devastating [invasive species] are on the way," said fisheries biologist Darrin Reid, in charge of the invasive species program at Keji. "But … we need to study these things, we need to research these things, we need to fight them where we can and see what we can do.

"You can't just lay down and let them come in and take over."

Parks Canada is responding on a number of fronts.

• Under new angling rules all native species like brook trout must be released. Angling is allowed only with a single barbless hook. Treble hooks are banned. Chain pickerel must be kept and turned in to Parks Canada. It wants to know what they are eating.
• Trap nets are being installed to create a baseline of information on native species before chain pickerel move in and take over.
• Environmental DNA (eDNA) water sampling capable of detecting the presence of a species through traces of DNA is being used to track the spread of chain pickerel.
• On land, six recorders that resemble wildlife cameras have been installed throughout the park to listen for frog calls. The devices are programmed to record for five minutes per hour from dusk till dawn. The software can distinguish frog species, even indicate how many are present.

"When chain pickerel move into a system, frogs are some of the first things to go or they start getting wiped out pretty quick," said Reid.

"So we're taking this baseline data with these recorders. We're measuring this in areas where we have pickerel, areas where we don't have pickerel and in areas where we're going to fight pickerel."

Creating a sanctuary

Parks Canada is also buying an electrofishing boat. It carries poles that can be dipped into the water, sending an electrical current into the water to stun fish.

Native species will be released. Chain pickerel will be removed permanently.

Parks Canada plans to use it up to 40 times a year, targeting pickerel in Mountain Lake and Cobrielle Lake, which will be sealed off as a sanctuary.

"They're fair sized and they're great brook trout habitat," said McCarthy. "It will provide a refuge for native species if we're successful."

"The idea is we'll put the barrier up. Yes those invasive will be in there as well. They will spawn. But we think we can fish it down with the electrofishing boat. It's a very effective tool."

Parks Canada hopes in some places an equilibrium will be established where chain pickerel and native species like brook trout co-exist.