Why should we care about invasive species?

This past week was Invasive Species Awareness Week in Canada.

It is a collaborative campaign focused on raising awareness about invasive species and how to protect Canada's natural spaces.

But why should we care about invasive species in Ontario? And what are some of the tangible impacts they make? To answer those questions, several experts in the field shared their knowledge and concerns about three key invasive species that pose a significant threat to our native species and bio-diversity.

If you have ever gone fishing on Lake Superior or Lake Huron and caught a lake trout, there's a reasonable chance that fish had a circular scar on it.

Those scars are made by sea lamprey, perhaps the most famous – and insidious – of all the invasive species in Ontario. They are such a serious problem that millions of dollars are spent annually to keep them under control.

This fish parasite was native to the Atlantic ocean, but was documented in Lake Ontario as early as the late 1830s, said Chris Sierzputowski, an aquatic science technician with the Department of Fisheries and Oceans, Sea Lamprey Control.

The construction of the Welland Canal in 1829 removed the natural block of Niagara Falls, and from there the lamprey began the move throughout the Great Lakes.

"At one time in the upper Great Lakes, both Huron and Superior had viable lake trout fisheries," said Sierzputowski. "They were harvesting almost 15 million pounds of lake trout annually. And within a decade, that 50 million went down to 300,000 pounds."

The infestation and population overrun of lamprey was so bad in the early years, that in some areas  you could not catch any more lake trout at all, Sierzputowski said.

Today, the lamprey is fought on both sides of the border thanks to a bi-national effort.

Sierzputowski said the primary method of control is the application of the lampricide TFM that targets sea lamprey larvae in nursery tributaries.

In the concentrations used, TFM kills larvae before they develop lethal mouths and migrate to the lakes to feed on fish.

However, Sierzputowski said the war on invasive lamprey can never stop, as they are a very resilient parasite.

"We have a very large mandate, and if we have to treat all five Great Lakes, there is over 400 streams that produce lamprey," he said. "And annually we treat anywhere from 60 to 70. So it's a huge job and we have only a short window."