Sure looks like it. Terrible! First they cut open pelican pouches, now this? I know that some fishermen don’t like cormorants in particular (though they are fine with pelicans, ospreys, herons, frigatebirds, etc.)
@Great Argus
You’re right. I knew it was too white and had too straight of a bill. Anyway, loons are considered bad luck by superstitious fishers. That wound doesn’t quite look natural to me.