It was the Saturday after the Fourth of July 2012 and Nauset Beach in Orleans was packed with thousands of swimmers, surfers and kayakers. They were unaware that just 150 feet offshore, Large Marge, a 16-foot-long female great white shark, was swimming slowly north, undetected in just 8 feet of water.
(From Cape Cod Times / by Doug Fraser) – Then, Marge did something Cape Cod great whites rarely do. She surfaced, and the surreal sight of that flat gray triangle gliding along and the enormous shadow beneath it immediately caught paddleboarder Dana Richardson’s eye.
Richardson shouted a warning, waving his paddle at kayaker Walter Szulc Jr. who was unaware that he was being followed until he looked over his shoulder, saw the fin at arm’s length and the big gray body slipping under his small plastic vessel.
It was the photo that shot around the world, even though Large Marge didn’t cause any harm other than momentary panic and a temporary beach closure.
According to one theory, Marge might just be one of a handful of dominant great whites that have set up territory on the Outer Cape like a lion at a watering hole, where she prefers to hunt for seals without much competition from other sharks. If that’s true, she’s staked out an area off Orleans and Eastham that may be the most popular and populated territory on the Cape for another water-loving species — us.
It was only fitting then, that the next time Marge made the news, her exact position, right down to every beat of her tail, was tracked with unprecedented precision and recorded on high-definition video by a 5-foot-long self-propelled yellow torpedo. A relatively new marine research tool, this autonomous underwater vehicle is known by its commercial name REMUS-100, but dubbed SharkCam by researchers. It shadowed the big shark like an attendant remora, showcasing groundbreaking technology developed by the Woods Hole Oceanographic Institution’s Oceanographic Systems Laboratory with funding from the Discovery Channel. It’s a leap forward in shark science, adding the third dimension of real-time video, that also has major implications for public safety.
“It tells us where sharks are spending their time, how they may approach seals and swimming and surfing beaches,” said state shark scientist Greg Skomal who worked with WHOI researchers on the project.
SEARCHING FOR BETTER DATA
Skomal is the lead researcher in a tagging program that, since 2009, has fitted 39 great white sharks with an array of tracking devices including acoustic tags that continuously broadcast a unique identifying signal; archival tags that track and record the shark’s location and environmental data for months before detaching and broadcasting that information to researchers via satellite; and satellite tags mounted on the dorsal fin that send the location each time the fin breaks the surface.
While these devices will tell researchers where the animal has been, it is only an approximate location, which can be off by a quarter-mile or much more. And their whereabouts are not known for weeks or months after the shark has passed by.
WHOI engineers adapted the Remote Environmental Monitoring UnitS, or REMUS 100, outfitting it with as many as six high-definition cameras and an omnidirectional receiver that can home in on a shark transponder; doing so, they were able to know where a shark was with unprecedented precision in real time. It also gave scientists the unique opportunity to see the shark in its surroundings, adding another important dimension to their research. While following the shark, onboard instruments gather environmental conditions like salinity, water temperature and clarity, even bottom contours, and matched to the video recording, the data gives a fuller picture of the shark’s habitat and how it acts in that environment.
“We can get data from tags, but we don’t know what the sharks are doing,” Skomal explained. “What is it doing in the Sargasso Sea diving to 2,000 feet?”
Current technology also allows for the REMUS to be stationed underwater, dormant, waiting for a signal from a tagged shark to wake up and start tracking. It has the power capacity to track for eight hours but other models go for days at a time before needing a recharge. In the case of a territorial shark that might be hanging around beaches, having a REMUS nearby could be priceless.
“If we have a sentinel on duty that can follow these animals, then we are not reliant on a boat and plane to find them. It’s a cost savings and can get us much better data,” Skomal said.
‘UNDERWATER PICKUP TRUCK’
Still SharkCam is not inexpensive. It took about $ 325,000 in research and development funding to equip the first model and program it, but production models could be much less, possibly as low as $ 5,000 depending on the instrument package and accessories. Each tag runs around $ 15,000. Leasing the full array with two support personnel is comparable to what Skomal spends on a boat crew and spotter plane used to tag sharks, at around $ 5,000 a day.
The project was first proposed more than six years ago, Skomal said, as he was brainstorming with a WHOI researcher over how to use REMUS to get better information on the feeding behavior of basking sharks.
“The idea existed before we had the hardware to do it,” said Roger Stokey, a senior engineer in the WHOI Oceanographic Systems Laboratory who was charged with writing the complex programs that told SharkCam how to find and behave around the shark.
In 2008, the project received an internal grant from WHOI that got the effort rolling.
“It’s like an underwater pickup truck,” explained Amy Kukulya, a senior engineering technician at the systems lab who was the SharkCam project leader. Kukulya was standing in her lab, surrounded by racks of bright yellow torpedoes, some of which were partially disassembled, their skin stripped back to reveal the densely urban circuitry and bundled wiring that made up the guts of these hi-tech fish. Three hundred REMUS AUVs are in use around the world, doing everything from naval defense work, to bottom mapping, environmental research and underwater recovery at depths up to 20,000 feet. Although invented in the WHOI systems lab, manufacturing of the units for sale was turned over to Hydroid Inc. of Pocasset in 2001.
The vehicles generally are used in conjunction with stationary transponders, but researchers have developed it to be able to follow a boat. However, finding and following an animal, changing speed, depth and direction at will, was a new challenge. To do the video work, they had to do that, and get in really close.
“It’s like a game of Marco Polo,” Kukulya said, hefting a foot-long yellow transponder with fins that looked like a chunky mortar shell. Trailing behind the shark from a slender metal wire connected to the detachable blade of a harpoon lodged in its dorsal fin, the transponder listens for a specific signal from the REMUS.
When it receives that inquiry, repeatedly sent out in rapid intervals up to two seconds apart, it responds with its own message, a double ping, that REMUS onboard computers use to calculate location and depth. This constant rapid-fire conversation continues throughout the mission. A second dialogue also is running with scientists monitoring the progress on a laptop that gives the location of the two objects and allows for technicians to give the vehicle commands as needed.
But the summer ocean off Cape Cod teems with planktonic life that limits visibility, sometimes to just a few feet. For video, it didn’t do researchers any good to be 20 feet away and not be able to see the shark. Although it is recording video, it is not transmitting that to the surface and is essentially flying blind. Tracking a shark that can turn quickly and accelerate meant the REMUS had to act independently and make relatively quick moves on its own.
“The problem we run into is, we get to where the shark is, and it’s already gone,” Stokey said. “Our information is always a little out of date.”
They needed to anticipate where the shark was headed in the seconds between each signal and point the torpedo there. It was science at the intersection between the randomness of nature and the cold hard realities of mathematical formulas.
There was an art to approaching the shark as well. No one knew how a big shark would respond to a 5-foot-long yellow torpedo shadowing its every move while emitting an audible hum from its anodized aluminum propeller. Stokey had to program the SharkCam to maintain a respectful distance and adjust its speed to the animal’s own swimming style. There were a few times where the REMUS bumped into its larger companion.
“Our whole goal was to get as close as possible but not spook the shark,” Stokey said. “In all honesty, it didn’t mind too much. We didn’t see a lot of reaction to it.”
UP CLOSE WITH MARGE
Operating on a shoestring budget, the team tested tracking capabilities on Skomal as he was dragged through the water by an underwater scooter, then on basking sharks, and finally, the big test in July 2012: six trips to tag and track great whites off Chatham.
This was The Big Show, Kukulya said, with a crew from the Discovery Channel on board to film it for Shark Week. They’d all done it many times and knew the technology worked, but how it might perform before the cameras was suddenly in question. Kukulya had what she called “sweaty palms” as she waited on board the tuna boat Ezyduzit, the Cape Cod Shark Hunters vessel Skomal uses for shark tagging. The spotter plane cut ever tighter circles as it guided them to the shark, the jumpy, staticky back-and-forth between pilot and boat captain over the two-way radio crackling across the water.
Even veteran harpooner and vessel captain Bill Chaprales had some butterflies. The big transponder was more than 10 times heavier than the typical shark tag. It threw off the balance of the 12-foot-long light aluminum harpoon he typically used. He’d practiced on foam targets to get it down, but this was Shark Week, performing before a national television audience and with an instrument worth about $ 15,000 that no one could afford to lose.
Chaprales put the harpoon into the shark with a quick downward thrust of his arm. A rubber shock absorber stopped it from penetrating any deeper than the base of the fin and the head toggled sideways to catch in the connecting tissue.
Kukulya helped put the REMUS into the water. The prop started up and Kukulya was relieved when it made a quick turn and headed off in the direction of the shark.
“I knew we had made a huge step forward,” Skomal said, but SharkCam had trouble keeping up with the first three sharks as a stiff opposing current and the shark’s own cruising speed outstripped the maximum speed the AUV could muster. On July 27, just a couple of weeks after the kayak photo was shot, the current that had plagued them all month abated. SharkCam was able to get up close and follow Marge for more than three hours as the big female cruised from Chatham, swinging toward shore to within 50 feet of Orleans beaches, then hunting seals in the surf at Nauset Inlet.
The video images made for great TV, and were clear enough to reveal fresh scars around Marge’s gills and pectoral fins, likely from a male holding her with his jaws while mating, Skomal said. That reinforced one theory that the Cape might be a great white shark breeding ground.
“I was extremely surprised that it worked,” admitted Skomal. “We were skeptics about the whole plan, but we got it to work.”
The Discovery Channel liked the technology so much that they funded a SharkCam trip to Guadalupe Island off Mexico in October and November of 2013 to film Pacific white sharks in crystal clear water. That footage, Skomal said, is amazing.
“Having cut our teeth off Chatham and Provincetown where the water (visibility) is tough, it forced us to get very good,” Stokey said.
Skomal believes SharkCam opens a whole new window into the mostly unknown world of great white sharks. Getting a closer look at essential life processes that have never been filmed before — such as mating, giving birth and feeding — will have benefits for conservation and public safety, he said.