What are GSM?

In my experience, FHM will spawn quite well on just about anything that is laying on or near the bottom and often times, they'll spawn on things that aren't so close to the bottom like a floating pallet or a lily pad. I like to place FHM spawning sites in water 4"-12" deep. Any deeper and they are forced into water deep enough for bass to more easily prey on them. FHM really aren't picky when it comes to spawning sites though. I have access to a lot of broken concrete blocks, so... That is what my bluntnose minnows use to spawn and bluntnose minnows and FHM spawn in the exact same manner. I place the broken pieces in the shallow areas and the fish spawn away. There are also rip rap around the overflow area that gets heavily used as spawning sites. I watched a male rigorously guarding the underside of a dead cattail blade. I guess that was his chosen spawning site.