Nutria are a rodent, an invasive species in Louisiana. They love water, and they've been here long enough that we consider them part of the landscape, but still. They dig holes in levees, undercut banks, and generally make a nuisance.
My son is a sewer systems operator, responsible for the sewer treatment of a small town in Louisiana. He has ponds that treat the water. I don't know the details, but he has it down to the science. Turning dirty water into clean water. And nutria is a problem. If they get into your ponds, they'll undercut banks, dig tunnels in weirs, and generally create turmoil.
So, he was telling me a story. "We had a nutria infestation and decided that the best way to control them was to shoot them. So, we got some .22 rifles and one of the crew brought some subsonic ammo. Less noise. So, early in the morning, we set up on one side of the bond, and watched the opposite bank. In a few minutes we saw some nutria come out."
"The pond is about 100 yards across it, and I took a good sight on a big ole rat. I hit him solid and he just kind of flinched and looked around.. So, I popped him again. Same story. At a hundred yards, I think those subsonics had run out of steam. "
"So, next morning, we're back with good hi-velocity ammo. When the nutria came out, Bang, flop. Next one comes out. Bang, flop."
I asked him if they had controlled the population. "Yeah," he replies. "We've got them on the run. But we learned that subsonics might be good for some things, but not for long-range nutria."
I'm just passing this on for the general knowledge base.