The number of zebra mussels spreading through Manitoba waterways is on the rise again.

Zebra mussel populations in Lake Winnipeg and the Red River have increased significantly lately, Manitoba Conservation and Water Stewardship said in a release.

The invasive fresh water mollusks have been found suctioned to more boat sides, beaches, buoys, docks and ladders at Grand Beach, Victoria Beach, Winnipeg Beach, Matlock and Sunset Beach.

The St. Andrews lock and dam in the Red River is also becoming a zebra mussel trouble spot.

The province reminds boaters and beach-goers that it is illegal to transport zebra mussels between lakes and rivers in the province.

Manitoba Conservation has compiled a list of tips for boaters here to help prevent the spread of zebra mussels.