predyotevarmint,
You are right the Great Blue Heron is very distructive in what they kill. I worked in Lancaster county years ago and had a friend that raised beautiful trout in two ponds below Quarryville, Pa. He also had one pond with Largemouth bass in it. The trout pond had running water in it and was about two and a half ft. deep, but the bass pond was about 11 ft. deep so tyhe herons could get the trout. He allowed me to fish for the bass catch and release. Well one day he said he see's blue herons getting his trout and asked me if I would start shooting them....I said I'd like to but they are protected. He said he didn't care, he wanted them dead, costing him too much for replacing trout. I said if I saw some I'd do it, but I never had any intention on killing any and never did. I just told him I didn't see any, or I saw one flying over now and then but wopuldn't land. He knew I always carried a pistol but thats all.