I usually use limb lines and short trotlines on rivers targeting flatheads. Bait depends on what we can catch in the area usually 4 to 6 inch bluegill or big gizzard shad. We catch a few nice fish but when we check our lines in the morning I find a lot of hooks empty where fish have gotten off. I use a 6/0 circle Sea eagle claw hooks. Is that the right size?Or do I need an entirely new hook? And should I be checking the lines at night?

I would think 4-6 inch bait would require a 8/0 hook or bigger depending on where you hook your bait.

I don't know because I prefer to catch them on a rod and reel. Maybe turtles. Maybe they just got off. Do you ever fine your hooks bent or slime all over the lines? I've heard too that cormorants will rob you of your bait as well. My ex father-in-law would find dead cormorants on his lines. Better hope raccoons don't learn how to snorkel or you'll never catch another catfish.

Some folks just don't understand how smart coons are. We were out in deer blind at a buddy of mine's place years ago. It was just barely light enough to see movement at the protein feeder. As it got lighter we realized there was one coon on the spout, raking it off to another one on the ground. And they would actually trade places, so they both could eat.

I have had coons pull in a stringer of catfish during the night and eat all on the meat off the backbone.
Also had one manipulate the locks on a yeti cooler and steal a tomahawk ribeye. We heard him digging around in the cooler when we were sitting around the campfire. We thought it was someone stealing beer. We ran over and chased him up a tree. he sat there and ate the whole damn steak. When he finished he came down the tree like The alien in the movie Predator. He ran us all off in fear of our lives.

Are there a lot of gar in your area? If it's not an incorrect hook size, I'd guess gar. That happens to my lines quite a bit when using cut bait.

It's also possible someone else is "checking" the lines for you.

We used to have a few bent hooks using size 6 and 7's, so we went to 8's. They really did bend 8's so we went back to 7. I think the wider gap gave the fish more leverage to bend and straighten the hook. These were just ss trotline hooks, I hand sharpened all hooks and like said gars and turtles will strip bait but usually you'll hang one

If your baiting them before dark chances are the gar are stealing your bait..

Check them periodically. If you set them and come back the next day you will definitely miss some fish

I would think gar too.

Gar and Softshell turtles are the culprit on my trotlines most of the time with the turtles being the main problem. I've caught so many of those things it's not even funny. usually in the foot or the edge of their shell but sometimes in the mouth. I use 6/0 octopus circles.

Almost guarantee it’s turtles this time of year.