Rusty crayfish now in Rainy

Our bay on Turtle Island of Rainy Lake traditionally has had some thick aquatic plant growth.
It harboured northern pike and bass, and was a great growing ground for the schools of young bass that were hatched on beds in early summer.
Most of those weeds have disappeared this summer–much to the delight of swimmers who choose to enter the water from our beach area.
I have a favourite fishing hole at the top end of Rice Bay on Rainy Lake that traditionally held a great variety of fish. If I had a young person who wanted to fish, this was the go-to spot for success.
We would not target a specific species because we could catch a variety of species and sizes. But that thick weed patch has disappeared, as well. Instead, the fishing graph shows a barren weedless bottom.
Much of Rice Bay’s weeds have disappeared. And other parts of the south arm of Rainy Lake seem to be losing their weed areas.
One wonders if our cooler-than-normal spring has reduced the growth of aquatic plants (Rainy warmed up much slower than usual) or if an invading species has targeted the aquatic plants on Rainy Lake.
Since some parts of the lake have normal aquatic plant growth, and other parts have seen the plants disappear, the weather probably isn’t the issue.
The Ontario Ministry of Natural Resources and Forestry has identified a rusty crayfish population on Lake of the Woods, as well as in boundary waters adjoining Quetico Provincial Park.
The Department of Natural Resources in Minnesota had identified Beltrami, St. Louis, and Lake counties as having populations of rusty crayfish.
The rusty crayfish was identified in Ash Bay in 2015. They probably have moved across the basins and are voracious eaters of aquatic plant life.
Rusty crayfish originated in the Ohio River basin and probably were brought into new bodies of water by fishermen using them for bait. Studies by Lodge and Lorman in 1987, Olsen in 1991, and Wilson in 2004 indicated rusty crayfish have been shown to reduce aquatic plant abundance and diversity.
The crayfish are known to eat large quantities of aquatic vegetation, reducing spawning and nursery habitat for native fish. It also competes with native species, often causing the disappearance of native crayfish.
They also seem to have an ability to avoid being eaten by fish than native crayfish, thus increasing the likelihood that their population will increase while native species will decline.
As the rusty crayfish population expands, more aquatic plants will disappear and much fishing habitat will change.

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