What are the signs to look for?  From what I understand, they go into shallow water and around boat docks and the bass follow.  This is usually post bass spawn in the spring.  Is that correct?   When else do the shad spawn?

You know they have spawned when they roll over and light up a cigarette.  Some even rent videos of other shad spawning to get them in the mood. ;D  Sorry, just couldn't pass this up - I tried -- honest.

Threadfin shad can spawn several times a year depending on water temperatures.

http://www.outdooralabama.com/fishing/freshwater/fish/shad/threadfin/

Where you live will control the amount of shad spawning. In the southern areas they will spawn both spring and fall if conditions are ideal. However if conditions aren't ideal shad, (threadfin) are able to abort the spawn and resorb the eggs. Ideal conditons consist of water temperature, conditon, and the presence of hiding area. Recruitment is highly dependant on presence of hiding area, and they will adjust the spawn amount based on this criteria. This is a unique characteristic to shad.

As the recruitment develops they are less likely to bass food as they are to be consumed by other small fish such as bream. As they get larger they become ideal for bass and one of the most sought after forage. They will really excite a school of bass as they swim over their location.

Presently here in Florida the spring spawn is getting hammered and goes on throughout the day. Sharp eyes and some local knowledge will put you into the heart of the foray. Presently we are seeing catches that go into the hundreds.