Identifing bait Fish, Alge and Plankton on your Sonar?

:cool: Need some help here with identifing what my fish finder is showing me. Have no problem identifing game fish or bottom structure, but her is the problem; Often I see small to large, semi solid balls of what I have always assumed to be bait fish (shad). Also I have recently observed massive clouds (almost solid) of something extending from subsurface down to ~40 - 60 feet. It was not a school of Stripers. Any way to determine if this type of image is shad or plankton? A near by boat was pulling in a striper about every 30 minutes. Oh, fishing on lake cumberland.

Any thoughts or web links on information? :confused: