'Very aggressive competitors': New invasive fish detected in Ontario

Eurasian ruffe is a member of the perch family

A new invasive species of fish has recently been detected in northeastern Ontario.

Sydney Currier is with the Invasive Species Centre in Sault Ste. Marie and says the Eurasian ruffe was reported in St. Mary's River in May.

The spread of the invasive fish is not a welcome sign for sports and commercial fishers.

"The Eurasian ruffe is suspected to be spreading east along the northern shores of Lake Erie and has been recently confirmed just outside of Sault Ste. Marie and then the United States," said Currier.

"It's been found along the southern shore of Lake Superior, in Lake Michigan and as well as Lake Huron."

CBC: Eurasian ruffe is an invasive species that poses a threat to native walley and perch populations. (supplied/Invasive Species Centre)

Eurasian ruffe is an invasive species that poses a threat to native walley and perch populations. (supplied/Invasive Species Centre)

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Currier says it's a member of the perch family that has travelled from Europe and Asia to the Great Lakes area through ballast water from ships.

She says it's not been high on people's radar but hopes more people will learn how to identify it to prevent its spread.

"It looks very similar to a perch in terms of body shape and colour, but it's quite small. It's only around six inches long," she said.

A sure way to identify it, says Currier, is that its dorsal and adipose fins are connected.

Its arrival is bad news for native species and those who rely on them.

"The concern with ruffe is that they're very aggressive competitors with our native fish, particularly our native sport fish, " she said.

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"So yellow perch and walleyes, they compete with those sport fish that are of important economic and social value with recreational and commercial fishing. And they compete with these native fish for food and habitat, and they also prey heavily on their eggs and their young fish."

Currier says to prevent the spread of Eurasian ruffe, boaters should not use them as bait, should empty their bilge water and dry their boats before moving between bodies of water and never dump their bait buckets in the water.

In fact, Currier says the sale or possession of live or dead Eurasian ruffe is prohibited by law.

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This article, written by Kate Rutherford, was originally published for CBC News.