Bringing out the big fish?

[Giuga10]

Hi, I constantly fish local stormwater ponds (like on a daily basis) and am always amazed at what these ponds produce. One thing that I've always wondered is why the big fish dont bite. In 2009 I used to be able to consistently catch 1 LB Largies but ever since these ponds have gotten attention from people who fish for keeps, you're lucky to catch a few baby Bass and Pumpkinseed's. I know that the fish are in there because I can see them occasionally jumping out but not to be caught. I've also found a 3 LB Bass carcass that had been torn up so the big fish are obviosly there. The ponds around my house contain Largemouth Bass, Bluegill, Koi, Carp, Bullhead Catfish, and many other common species. The Carp I have no problem with because those are the only fish that can be caught big but I do have trouble bringing out the big fish. I have tried for an entire week trying to catch a Koi at one of the ponds and have failed every time, but have had fisherman right beside me pull out 2 LB'rs but I've had no luck (Michael you know which pond this is).

I'm just hoping for some tips to pull out good sized fish in these ponds. I've tried everything from Corn to Pike lures but NOTHING.

Hopefully someone can help,
Thanks,
Giuga10