Zebra mussels have been found in the Red River just south of the Manitoba border.

A significant amount of zebra mussel larvae (or veligers) were picked up in June surveys of the river from the southeast to northeast parts of North Dakota, an official with the North Dakota Game and Fish Department said in a release.

Zebra mussels were first found in Manitoba in 2013. This spring, they were found on a private dock in Selkirk Park and zebra mussel larvae were found in the Red River near Emerson. The province said that's the first time the larvae have been found in that part of the river, which is just above the North Dakota border.

"Although these results are not totally surprising considering the recent findings of large numbers of zebra mussel veligers in the Red River at the Canadian border, and in past years near Wahpeton in the Otter Tail River in Minnesota, the results are certainly surprising in that so many veligers were detected at each of the six sampled sites," Fred Ryckman, North Dakota Game and Fish Department aquatic nuisance species coordinator, said in a release.


The province experimented with a potash treatment to poison the mussels in several harbours along Lake Winnipeg in 2014. (Terri Trembath/CBC)

"And it's even more incredible considering that in similar sampling over the past several years we've only detected about a half dozen veligers in total."

The microscopic mollusk larvae are released by adult mussels into the water and attach to rocks, docks, boats, bridges and pipes. The accumulation of mussels on surfaces can damage underwater infrastructure.

They compete for the same food sources as some game fish, which can throw off food-chain dynamics in fresh water ecosystems. Zebra mussels are also filter feeders. Their eating habits can dramatically alter the complexion and nutrient-levels of fresh water basins.

Once invasive species like zebra mussels get into waterways, it is almost impossible to get them out.

"There really isn't anything we can do to remove the veligers or any adult zebra mussels from the river," Ryckman said in the release. "But we can be on alert and do everything we can to prevent them from being moved to other bodies of water."

The northward flow of the Red River means more of the invasive species could be headed for the province.

In May, the province announced it will be enlisting the help of detection dogs to sniff out the presence of mussels on boats and aquatic equipment.