squirrels

Our orchard is overrun with squirrels who are chewing on bark and roots and doing severe damage. The orchard is fenced which means few predators. There's a bobcat but s/he can't keep up and squirrels are overpopulating. We're having trouble live trapping them and, even if we're successful, aren't sure what to do with them. Catch and release is illegal and we can't find any humane ways of killing them. Thoughts?