Another thing you can do is illuminate the water near your pier some night. Young perch and bluegill are phototactic and will be drawn to the light, and so will their food source zooplankton. Even laying on the pier with flashlight pointing into the water may do the trick if that's all you have.

I use light to concentrate both species to feed train them. It especially works well with yellow perch.

See this link for a short video of bluegill under my feed training light. I can post a link for perch under my feed training light if you wish.

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=176430&fpart=3

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.