Tony, I sometimes catch scup at night on fresh squid strips at the docks in Edgartown - in deeper water. Only do that when I've run outta eels and am desperate to use scup for bait.
It's usually a better bite during daylight hours.
Couple a things I learned about live lining scup ... the sharpies I've fished with don't handle the scup with their bare hands, they gently use a rag. I don't know exactly why, but I think it has to to with preventing removal of the protective slime and to prevent your own scent from being imparted to the scup (which could scare away bass.)
Also, chop off the dorsal fin just before you are about to use the scup ... emits a little blood chum and also makes it easier for the bass to swallow the bait.
-WW