Co-Captain Jody Whitworth and master of the Martha's Vinyard OCEARCH team Brett McBride prepare to stabilize a great white shark named Amy. Before taking measurements, blood and securing real-time technology tags, a device is inserted into the shark's mouth to irrigate its gills. (Image: OCEARCH).
How to catch a great white shark
To tag the sharks, the OCEARCH team first goes fishing with a hand-held line tipped with special barbless hook, engineered so it won't injure the animal. The team then brings the shark alongside their 126-foot boat, which has an underwater hydraulic lift that can hoist up to 75,000 pounds. That capacity is needed since the team is not only lifting what could be a one- to two-ton shark but also the water around it.
Once the shark is above the water line, from three to eight scientists get to work on it like a NASCAR pit crew, first placing a wet towel across its eyes to calm it and an irrigator in its mouth so it can breath. The crew then rolls the shark on its side to surgically implant the first tracking tag in its belly.
That device, known as an acoustic tag, is about the size of a Sharpie pen. It can remain in the shark for as long as 10 years and can be "heard" whenever the animal swims to within a quarter to a half mile of underwater buoys that can pick up a radio frequency specific to marine tagging operations. Throughout the world, marine biologists have anchored such buoys, which can record an acoustic tag's unique ID as well as the day and time.
The OCEARCH team tags a great white shark off of Cape Cod, Mass.
Once the acoustic tag is in place, the OCEARCH crew rolls the shark back onto its belly and attaches a Smart Position Or Temperature Transmitting (SPOT) device. The SPOT tag is placed high on the shark's dorsal fin because its radio ping can only be received when the shark breaks the surface of the water and a satellite is in position to receive the signal. The longer the fin is out of the water, the more accurate the data. There are six ARGOS global positioning satellites orbiting the earth that can pick up a SPOT tag's ping at any time.
"The ARGOS satellite is only around about every two hours. Then the fin has to stay out of water for minute or two to get a good fix," Whitney said. "It's ridiculous that this works. It's pretty amazing when you look at the map and understand how many fixes we get on these sharks."