I have always chummed when possible. Normally this is done by cutting up the unusable pieces of bait (i.e.,. the heads of anchovies or soft parts of mussel) and dropping them into the water. However, if you're like me you probably eat a lot of seafood and thus have usable chum at home. I always save the shells from shrimp after they are cleaned and save the skin, or any other parts of fish, that are not used for cooking. Was thinking of this last night when I filleted the skin off some fish, cut them up, and packed them in a Ziplock in the freezer. All chum is not the same as far as ability to attract fish but I think all chum is better than no chum.