It's always blame whitey! I don't think this was a white shark either - never heard of one near NJ
The Great White attacks different species of pinniped using different techniques. Northern Elephant Seals (Mirounga angustirostris) are not easy to catch. They are station wagon-sized, phenomenal repeated deep-divers, and very powerful swimmers. But at the surface, Elephant Seals have all the maneuverability of an aircraft carrier. In order to tackle an Elephant Seal, a Great White typically attacks from below and behind, immobilizes the seal with a tremendous bite to the hindquarters, then retreats and waits for its prey to bleed to death before returning to feed. Hunks of blubber and flesh are sawed away at the surface, but taken to or near the bottom to be swallowed.
This so-called 'bite-and-spit' strategy is typically employed by White Sharks feeding on adult Northern Elephant Seals, but does not hold for pinnipeds of lesser dimensions. Smaller seals, such as the 1.5-metre Harbor Seal (Phoca vitulina), are grabbed at the surface and pulled underwater until they stop struggling, then eaten at or near the bottom; juvenile Harbor Seals are simply plucked from the surface like grapes and eaten whole (Harbor Seals seem like the perfect White Shark snack food: they're abundant, slow-moving, and bite-sized - sort of Phoca McNuggets!) The 2.5-metre-long California Sea Lion (Zalophus californianus) is a more powerful swimmer than the Harbor Seal, and is typically attacked by a White Shark from below, struck in mid-body, dragged below the surface until it stops struggling, then eaten at or near the bottom.
Reflecting upon the White Shark's predatory modus operandi, several interesting patterns emerge. It is interesting that for all three species of pinniped, the White Shark stalks along the bottom, attacks at the surface, and feeds at or near the bottom. It is also interesting that divers attacked by White Sharks tend to be hit at the surface and grabbed mid-body, as though the shark had mistaken them for a California Sea Lion. What is especially intriguing, however, is that divers attacked by White Sharks are let go after the initial strike two out of three times . It seems unlikely that the mighty Great White can be so incompetent a predator that prey - once in its mouth - escapes 67% of the time. What's going on here?
To find out, A. Peter Klimley devised a bizarre modification of Scott Anderson's surfboard experiments. Klimley used a similar rod-and-reel rig to troll the waters off South Farallon with the carcasses of seals, pigs, and sheep (If Hemingway knew, he must have spun in his grave: 'The Old Man and the Sheep'?) White sharks attacked all three types of bait, but consistently rejected the sheep carcasses. Klimley speculates that the high energy demands of the White Shark may be a factor in rejection of food items. On a per unit mass basis, fat or blubber is very a energy-rich food. Since seals and pigs tend to be quite fatty they are 'accepted' after the initial strike; sheep tend to have a significantly lower fat content, and may thus rejected as 'low-quality' food. So, putting all the pieces together, it seems that divers who are attacked by White Sharks are visually mistaken for sea lions and then spat out because they're just too damn skinny to be a worthwhile meal.
And speaking of fat, there is good evidence that blubber scavenged from whale carcasses is a major source of energy-rich food for White Sharks. In August 1979, a 50-foot (15-metre) Fin Whale (Balaenoptera physalus) carcass was discovered floating 40 kilometres off Montauk, Long Island, attended by as many as eight White Sharks. In an attempt to learn how much food a Great White needs, Frank Carey of the Woods Hole Oceanographic Institute (WHOI - known as 'hooey' to the irreverent) attached a sonic tag to a 5-metre individual feeding on the whale carcass. Carey was able to track the White Shark for 3.5 days - during which the shark swam 118 miles (190 kilometres) to Hudson Canyon - and obtained base-line data enabling him to make a rough guesstimate of this shark's energy budget (or, to put it more informally, to figure out how many miles/kilometres per mouthful of blubber). The results were surprising: despite the relatively high internal temperature and active lifestyle, Carey calculated that this individual wouldn't need to feed again for 1.5 or even 2 months!
http://www.elasmo-research.org/education/white_shark/catch2.htm
As far as spectacular breaching, take a look at this Mako: