Mako sharks follow bluefish. Many sharks are taken by tuna fishermen. He's learned that promising areas could be anywhere. Generally, he goes south of Block Island along the 30 fathom curve, or south of Montauk Point at the 40 fathom curve. You're looking for contour where the bottom drops off sharply.
Sharks like to follow the edge.
Dubrule keeps 150 pounds of chum on board all the time. He has a freezer. You want your baits at different depths in the slick. Remember it fans out the farther it gets from the boat. He'll use a balloon for a float, tied on with dental floss so it breaks away when a fish hits.