Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations 20 pound blue cat lower fish population??

I may be way off base, but I have a very noticable decrease in LMB and BG population in my formerly overpopulated 6 acre pond. My broth er in law caught a super fat 20+ pound blue cat a month or so ago and threw him back in. Could blues decimate the population of fish in my pond?? I'm seeing very few bass and bluegills from the banks in the last 60 days. Could this be possible? Thanks in advance for your input!
Mark

PS: I have LMB BG Black Crappie
CC and at least one blue cat. This fish had to be introduced by someone locally as it's the only one ever caught in the 5 years I have owned the pond. BTW There has been no sign of a fish kill all year.