WINNIPEG -- First, Manitoba tried killing them with liquid potash.

Now the province will try to curb the spread of zebra mussels through legislation with strict rules for boaters.

Conservation Minister Gord Mackintosh introduced a bill Wednesday -- which the government touted as "the strongest in Canada" -- that would make it illegal to transport, possess or release zebra mussels. Boats in transit would have to be inspected at designated stations.

The proposed law would also require boaters to remove aquatic plants, which can carry zebra mussels, before taking their craft away from a body of water. The legislation, modelled on a law in Minnesota, would bring in new enforcement tools and probably increase fines levied against offenders.

"These proposed amendments and the regulations will make Manitoba's measures to address the threat of aquatic invasive species -- notably zebra mussels -- the most comprehensive in North America," Mackintosh told the legislature.

"It has been developed in synch and to complement stronger federal regulations that are now pending."

The invasive species, which has been in the Great Lakes for almost two decades and has spread throughout parts of the United States, was discovered for the first time in Manitoba in October 2013.

The province declared victory over zebra mussels in June after a unique experiment which doused four infested harbours with liquid potash. The harbours were initially declared mussel free, but they were discovered in Lake Winnipeg later in the summer.

The mussels reproduce quickly and can disrupt the food chain, clog water pipes and create algae.

"We are in for one long war. This is a very, daunting challenging task," Mackintosh said. "It's only individual action that can with any certainty actually stop the spread of zebra mussels.

"There's over 80,000 boats in Manitoba every summer. It only takes one to infest an entire lake."

David Carrick, founder of Fish Futures Inc., said zebra mussels would devastate Manitoba's $500-million commercial and recreational fishery if they take hold.

"This is a real threat," he said. "It requires dramatic action."

The government has been criticized by both the Liberals and the Opposition Tories for not acting fast enough to stop the spread. The legislature rises Thursday, so there's no chance for the bill to be passed until next year.

The lone Liberal member of the legislature, Jon Gerrard, raised the issue last week, asking why the government did not move quickly in August when it found out it had failed to stem the spread of the mussels. The NDP failed to "protect the other 100,000 lakes from infestation by zebra mussels this fall, as people were moving their boats around," Gerrard said.

Premier Greg Selinger said preventing the spread of zebra mussels is "a very important issue" and the province has been taking action. Canine units are being trained to detect the mollusks during "detection blitzes" in the summer and the province has purchased more decontamination units, he said.

"We took direct action every time there was a risk of zebra mussels showing up in our lakes."