This female crayfish is an invasive species and was found in Banff National Park/Parks Canada

Parks Canada is continuing the hunt for northern crayfish after the invasive species was found for the first time in a Banff National Park stream that flows into Bow Lake.

“I would love to know how it got there, but I don’t think we’ll ever know,” Megan Goudie, ecosystem scientist with the Lake Louise, Yoho, Kootenay Field Unit, said in an interview. “It really is the million-dollar question.”

The story began in July when an off-duty park Guardian — seasonal staff who speak with the public on special issues like wildlife co-existence — spotted what he was certain was a crayfish in the clear, shallow water of a stream alongside a popular trail.

The invertebrates look like miniature lobsters and live in other parts of Alberta, but shouldn’t be in the park. The Guardian took a video and then collected a scoop from his truck, but wasn’t able to catch the crayfish.

“Given his background, we were pretty confident of his description and report,” said Goudie.

The sighting was technically in the Bow River near Bow Lake, but really in an unnamed stream that’s ankle deep and only two to three metres (6.5 to 10 feet) wide.

A Parks Canada team, working in crews of two to four people, spent the next week and a half, crayfish hunting along a 400-metre (1,310-foot) stretch of the stream. They did visual inspections, electrofishing and kick netting and set minnow traps.

Parks Canada staff caught the crayfish in a minnow trap baited with hot dogs/Parks Canada

Goudie said the crayfish was caught in a “simple and effective” minnow trap baited with hot dogs after cat food, cat treats and pepperoni failed to work. “I put hot dogs in the trap on Saturday and then on Sunday we got the crayfish,” she said, adding it was a student from another part of Canada who suggested hot dogs.

The crayfish was captured Aug. 6 just 10 metres (33 feet) from where it was initially spotted, which is 30 to 40 metres ( 100 to 130 feet) from Bow Lake.

Parks Canada suspected the critter was a northern crayfish but there were a few other worrying possibilities, like the marbled crayfish that reproduces asexually and the rusty crayfish.

Under Alberta’s Guide to Sportfishing Regulations, it’s illegal to be in possession of a live crayfish. “We were able to kill it and still be able to gather the information that we needed,” Goudie explained.

A taxonomist confirmed it was a female northern crayfish of reproductive age. Females carry fertilized eggs on their undersides and so it’s possible she could have released eggs. Her age was unknown, but she was eight-centimetres (three-inches) long and the species can grow to 12 centimetres (4.7 inches).

Northern crayfish are native to a small part of mid-eastern Alberta and have spread across the province. And while it’s legal to capture them, you must immediately euthanize them because it’s illegal to be in possession of live crayfish. Under the Canada National Parks Act, it’s illegal to move aquatic invasive species like this between two bodies of water.

Parks Canada ecosystem scientist Megan Goudie does a kicknet search for crayfish in a stream in Banff National Park/Parks Canada

“The immediate concern is that any time there is a species introduced somewhere outside of its natural range, there are going to be implications in ecology,” said Goudie.

The area where the omnivorous crayfish was found is critical habitat for two species at risk — the bull trout and westslope cutthroat trout.

“We are concerned that if the crayfish population is established in this area, they could alter food chains,” said Goudie. “We don’t really, fully understand what the implications could be. It’s a really delicate balance in these mountain systems.”

Since Aug. 6, Parks Canada has continued to look for crayfish, expanding the search area to include three other tributary streams. “Crayfish can be a little elusive and so just because we haven’t found any doesn’t mean they are not there,” said Goudie.

Parks Canada also hopes to use environmental DNA to expand the sampling locations. All species shed bits of themselves in the water, and water samples collected through special filters can be sent to a molecular lab for quick results. “We’ve taken samples and are looking to partner with someone to help analyze because we don’t have in-house capacity,” said Goudie.

Nobody knows how the crayfish got to Banff, but Parks Canada suspects it was being used as illegal bait by someone who didn’t know the implications of releasing it to this water body. It’s also possible it was released from a child’s bucket.

Some people do boil crayfish and eat them, but that’s more popular in Louisiana than Alberta.

Parks Canada hopes to now convey three main messages.

“Don’t let it loose,” warned Goudie. “It’s illegal to release any organism into any body of water.
It can really start an invasion without ever knowing you’re doing it.”

Parks Canada also requires people “clean, drain and dry” their watercraft for at least 48 hours before using them in Banff. But a crayfish this size wouldn’t likely go unnoticed, and since motorized boats aren’t allowed on Bow Lake, only canoes, kayaks or floating tubes are used and they aren’t likely big enough for crayfish to hide.

Finally, Parks Canada can only do so much and needs the public to report anything suspicious, with a precise location, photo and video if possible. People can email [email protected]. In Alberta but outside park boundaries, people can call the provincial invasive species hotline at 1-855-336-BOAT (2628).

“Helping people to understand these things is really important,” said Goudie.