If your existing Bluegill spawn this spring, it would seem there'd be very little other fish to eat the Bluegill YOY, so your pond may fill up with bluegill without additional stocking.

You should also be chock full of fatheads right now.

Nothing wrong with additional stocking though.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."