Just by looking, i'd say thats a 10 pound fish or bigger if i had to guess. I caught one several years ago that was 16 and he didnt look too much different then that one there. It's a heck of a fish regardless. It sounds to me like you have a great place to fish, many times when im flathead fishing with big bait like that i wont even get a bite, but when i do finally get one it's usually a nice fish. So its worth it.