Ryan Casey’s video of a great white shark feeding on a whale carcass near Damariscove Island last week ignited a local feeding frenzy of its own: the media kind.  

Shark sightings during the summer beach season are a sure sell for the news business. Great white sharks are one of those truly awesome creatures that inspire both fear and wonder. Getting a nearshore glimpse, and even better video, of one is a rare opportunity here in Maine.  

Although great white sharks entered the American psyche in 1975 with the release of Steven Spielberg’s movie, “Jaws,” based on Peter Benchley’s bestselling novel, the earliest fossils for this species date back about 16 million years. Great white sharks have been an extremely successful species, whose only real threat over the eons appears to have been humans (talk about efficient killing machines!)

Despite our interest in them and all the hype a sighting creates, great white sharks remain elusive creatures, whose basic life history is still being pieced together by scientists across the globe.

Great whites are not common in the Gulf of Maine, but Maine waters are part of their current and historical range. Bigelow and Schroeder’s classic 1953 work, “Fishes of the Gulf of Maine,” the standard reference for fishery scientists for decades, devotes three pages to the great white and notes records of it in Gulf of Maine waters dating back to the 1800s.

Dr. Gregory Skomal, Massachusetts Division of Marine Fisheries research scientist and renowned shark expert, said in a telephone interview that great white sharks have been documented along the U.S East Coast from the Gulf of Mexico to the Canadian maritimes. Skomal said he does not currently think, as some have speculated, that changes in water temperature or prey populations have altered their range.
    
“They exist almost everywhere in ocean waters along the U.S. coast,” Skomal said, “but almost everywhere in that range, they are elusive and very difficult to find.”

The one exception to that rule in recent years has been the waters around Cape Cod in the vicinity of Chatham and that exception has presented a golden opportunity for East Coast shark researchers.

“We now have this area with a high density of seals and local bathymetry that has created a hot spot for white sharks,” Skomal said.

Skomal likens the ocean area around Chatham to a rest stop on I-95. Sharks migrating north or south stop along the way for a quick bite to eat and then, for the most part, continue on their journey.

How important this “rest stop” is to migrating sharks is not known but it is clearly important to researchers. Finding great white sharks on the open seas is difficult at best, but in areas, such as Chatham, where sharks reliably converge, the scientist’s basic task of finding their subject becomes a bit easier.

Skomal and his associates at the Woods Hole Oceanographic Institute and Ocearch have placed acoustic and satellite tags on 34 sharks since 2009. These tags provide researchers with data on where the sharks travel over long periods of time. Research has shown the sharks to be extremely mobile and very dynamic, Skomal said.

Most of the sharks tagged at Chatham have not remained in the Chatham area, and not surprisingly, four have turned up in the Gulf of Maine.

Chatham’s shark hot spot has been linked to the surge in gray seal populations in the region. Monomoy National Wildlife Refuge in Chatham, a sandy spit extending south of Cape Cod’s elbow, offers a unique wildlife habitat proximal to offshore banks known for rich fish stocks. It is also home to the largest haulout of gray seals on the East Coast. Gray seal populations around the Cape are estimated to be between 10,000 and 15,000. 

Maine’s seal populations are also rebounding with the protection afforded them under the Marine Mammal Protection Act. But Skomal is less optimistic that the Maine seal recovery will generate any great white shark hot spots in Maine, because here seals are spread over a wide area.

“There are lots of small haulouts. The seals are more spread out and so are the sharks,” Skomal said. Skomal also thinks great whites are more interested in gray seals than harbor seals, which are more ubiquitous in Maine.

“I think the sharks tune into gray seals more than harbor seals,” Skomal said. “They are a bigger target, slower and less attentive in the water than harbor seals. They also have a thicker blubber layer.”

Despite all the hoopla about shark sightings around Chatham, on Monday, three days into a month-long research effort to tag 20 great whites, Skomal said researchers were yet to see one.

Skomal estimates that there may be on the order of dozens of great whites in Cape Cod waters over the course of the summer. So, even in a hot spot, finding a great white is no easy task.

Skomal is optimistic that researchers will not only tag 20 great whites over the next month, but that they will also take samples from individual sharks. All the data gathered will provide keys to the shark’s basic ecology, much of which remains poorly understood.

What is it like to work on unraveling one of the ocean’s great mysteries and be in close contact with a great white shark?

“We’re dealing with one of the most charismatic creatures on earth,” Skomal said. “It’s exciting and it inspires me to do my very best work.”

Sue Mello can be reached at 207-844-4629 or suemello@boothbayregister.com