In digging into my siting I found that Thresher Sharks are a very common shark species for NJ waters and the 60* water temps and wrecks are key components in drawing them in. Although usually associated with deeper waters Thresher Sharks have been spotted in-shore for birthings, matings and for hunting when the pickings are scarce off-shore. Based upon my observation of a 5 foot body length with a tail about the same length an estimate of weight might be in the 150-250 pound range. Looking back what a great thing to have seen!
http://www.njfishing.com/NJ_Shark_Fishing.php