Well, you have LMB and that looks like a regular bluegill to me.
Electroshock survey will allow you to remove some LMB and bluegill, buy truly, you won't get them all. Cost of said survey is a few thousand gold smoullions.
If the LMB and BG came in from the stream, it's going to happen again and again.
If you still want the YP harvesting goal, then I'd be removing all LMB caught. I'm not sure about if the bluegill will be beneficial or not. I"m sure YP will eat some baby BG, but after the BG get a certain size, they'll survive.
