No they are not sterile. They are no different than autumn olive, Bradford pear and other things that are now becoming invasive. Man makes mistakes and will always make mistakes. Just like common European carp. I know you don't like bow fishing or indescrimate killing of critters. Sometimes you have to do what needs to be done. Pest control. No different from spiders, termites, mice and rats, starling and house sparrows.
You have a big heart Ham. One of the many things we like about you.