Cajun crawdads make unwelcome appearance in Nova Scotia lake

An invasive crayfish native to the southern United States has been found in a lake near Lower Sackville, N.S., outside Halifax.

It is believed to be the first confirmed detection in Canada of the red swamp crayfish, better known as the crawdad in Louisiana cuisine.

"This type of crayfish has severe or potentially severe impacts on ecosystems," said Sarah Kingsbury, an aquatic invasive species biologist with the Department of Fisheries and Oceans.

Kingsbury says they carry parasites, compete for space and food in the lake, eat fish eggs and alter habitat by burrowing.

The first crayfish was discovered by an angler in Three Mile Lake in 2022.

This summer, 70 red swamp crayfish have been trapped, a sign that they have survived the winter.

How it was introduced is unknown

It is not known how the crustaceans — which resemble small lobsters — were introduced into the small lake in Waverley, N.S.

The species is raised for food, sold for aquariums and used as bait by anglers. It isn't known if they have spread.

"We are concerned that it could move beyond the water body," Kingsbury told reporters at a lakeside media event Thursday. "Part of the trapping is to figure out where exactly it is and how close it would be to an outlet to a lake, for example."

The department is asking the public to report any that are found and not to move them.

Trapping and tracking

Saint Mary's University master's student Madison Bond trapped the first live crayfish in Three Mile Lake this summer. She will continue trapping until the lake freezes.

"My whole research is to look at the negative impacts that they have on this ecosystem as well as what is their life cycle in this colder climate," Bond says.

This is not the first invasive crayfish found in Nova Scotia.

Several years ago, the spinycheek crayfish was discovered in Freshwater Lake within Cape Breton Highlands National Park. It is native to some states in the northeastern U.S. and has now become established in Freshwater Lake.

There have been reports of red swamp crayfish detections elsewhere in Canada. This is the first one confirmed by Fisheries and Oceans.

Kingsbury says it is too early to say if it has become established in Three Mile Lake. That occurs when several generations are found in an area.