THEY RUIN EVERYTHING EXCEPT FOR THE TROUT WHICH THEY IMPROVED

I was a young girl I think the first time I read about the evil Patagonian Beavers that were killing all the trees and ruining everything, I even remember some lawyers from Canada saying they had gotten larger and were eating fish,  Apparently the Nazi-get-rich scheme of the 40’s had wreaked holy havoc on the landscape because in South America beavers have no natural predators.

Um…7 kinds of cayman? Maned Wolf? Oh well there was a problem because beaver chewed trees don;t coppice in South America. Or something.

This article made me laugh and laugh.

Beavers mean bigger trout

As it turns out, when both beavers and trout are exported halfway across the world, the beneficial relationship continues. The American beaver and the European brown trout have both been introduced in South America, and where beavers and trout occur together at the southern tip of that continent, the trout turn out to be bigger. In southern Chile’s Tierra del Fuego region, biologists have proven that introduced brown trout are direct beneficiaries of the construction activities of the introduced beavers.

According to a study put forth by Oregon State University researcher Ivan Arismendi, non-native brown trout living in Tierra del Fuego waters grow 14 percent faster when they live in watersheds where introduced beavers are present and active. Arismendi is originally from Chile but has been based in Corvallis since 2007.

“We show that beavers indirectly help with the growth of trout, potentially improving their survival,” said Arismendi, an assistant professor in the Department of Fisheries and Wildlife in the OSU College of Agricultural Sciences.

Well well well. those darn beavers are making things nicer for the trout which also shouldn’t be there!

As it turns out, when both beavers and trout are exported halfway across the world, the beneficial relationship continues. The American beaver and the European brown trout have both been introduced in South America, and where beavers and trout occur together at the southern tip of that continent, the trout turn out to be bigger. In southern Chile’s Tierra del Fuego region, biologists have proven that introduced brown trout are direct beneficiaries of the construction activities of the introduced beavers.

According to a study put forth by Oregon State University researcher Ivan Arismendi, non-native brown trout living in Tierra del Fuego waters grow 14 percent faster when they live in watersheds where introduced beavers are present and active. Arismendi is originally from Chile but has been based in Corvallis since 2007.

The outcomes, even in a locale where neither animal is native, are similar to those where both trout and beavers occur naturally. Beaver activity, according to the study, helps create better habitat for more energy-rich food sources that trout are known to eat. With more food, naturally, comes more growth for the trout. Even in remote Tierra del Fuego, where both the brown trout and the beavers are introduced from disparate parts of the world, this is a thriving relationship.

According to the study, which was published this month in the scientific journal Ecology and Evolution, trout living in waters where beavers had constructed dams are more likely to have larger sources of food available to them — amphibians like frogs, toads and salamanders also thrive in the slower waters of beaver-altered streams, and they provide a source of food that’s much more rare in naturally free-flowing streams in the region.

But wait, I thought they were very very bad. Are you sure they’re helping trout?

Beaver dams create profound changes in streams enhancing the input and retention of organic matter, nutrients, and other elements,” the study reads. “The greater availability of food resources and suitable habitat for trout in sympatry is most likely related to the physical modifications caused by beavers. The higher macroinvertebrate production in sympatry is supported by evidence from sites where beaver are native and introduced. Higher macroinvertebrate production provides a key food source that is used by introduced trout and native fishes and it may influence their observed higher growth rates, as is also seen in North America.”