Baitfish 

Distinct variation in otherwise constant stretches of cover, structure, or bottom type. Basically anything that “breaks up” the underwater terrain.

A tree that has fallen into the water.

Another term for baitcasting reel.  The spool turns during casting, unlike the spool of a spinning or spincasting reel.

Any of several species of weeds, located above the surface or underwater, of the genus Potamogeton.