Sharks go wireless as scientists tag them to track their travels
Meet Mary Lee, a great white shark that's the same weight and nearly the same length as a Buick. And, by the way, you may have been swimming within a few feet of her this past year and not known it.
Since last September, when she received an array of radio, acoustic, and satellite tags, Mary Lee has travelled from Massachusetts to Florida, often hugging the coastline so closely that scientists tracking her called beach authorities in Florida to warn them about her. The 16-foot, 3456-pound shark also headed into open ocean, taking a February vacation off the beaches of Bermuda.
"She was undoubtedly not the only one there. Sharks have probably been doing it for millions of years," said Nick Whitney, a marine biologist with the Mote Marine Laboratories in Sarasota, Florida. "We're learning things that ten years ago we would have never dreamed we could have learned about these species."
Whitney, who spoke from a research vessel off of Cape Cod, Massachusetts, is part of a team that runs OCEARCH, a nonprofit global shark-tracking project that uses four different tagging technologies to create a three-dimensional image of a shark's activities. OCEARCH is hoping to develop successful conservation and management strategies by studying shark habits in more granular detail.
While traditional research has focused on small-scale movements, the data being gathered by OCEARCH offers surprising new information about where sharks go and what they do. That's where the tracking technology is crucial.
A dorsal fin tag attached by OCEARCH uses a satellite to track a shark's position each time it breaks the surface. Other tags include an RFID implant whose ping is picked up whenever the shark passes a special, underwater buoy; an accelerometer, similar to the technology used in an iPhone or Nintendo Wii, that detects up or down movement; and a Pop-off Satellite Archive Tag (PSAT), which acts as a general archive, recording average water depth, temperature and light levels.
"On average, we're collecting 100 data points every second—8.5 million data points per day. It's just phenomenal," Whitney said. "Second by second, we can pick up every tail beat and change in posture."
One of the surprises the tracking data revealed is that white sharks don't always stick to cold water, as previously thought. Some even venture into the Gulf of Mexico during the summer.
In addition to in-depth data, what sets OCEARCH apart from past shark-tracking projects is that anyone—from a child in grade school to a television arm-chair warrior—can see the tracking data at the same time as researchers on the OCEARCH web site.
Each shark's location is represented by an icon on a Google Maps-based TruEarth Viewer. By clicking on the icon, a user can get detailed information such as the species, gender, size, weight, length, as well as where and when the shark was tagged. A user also gets images of the shark as it was being tagged.
By drilling down further, and clicking on the "Where Have I Been" icon, a user can also see a track of where the shark has been since being tagged, in some cases see a detailed trail over the course of a year or more.
OCEARCH expedition leader Chris Fischer calls the methodology "open source" research, since all scientists see the data at the same time; nothing's proprietary. Within a week, OCEARCH also plans to launch a "digital hub" shark tracker platform with a real-time social media interface that allows researchers to post FAQs and videos to the most popular social networks: Facebook, YouTube, Instagram or Twitter, according to OCEARCH spokesman Chris Berger.
OCEARCH will also be launching a Science, Technology, Engineering, and Mathematics (STEM) Education-based curriculum for K-12 students. "We currently have 30 lesson plans for sixth through eighth graders, and will have more for K-12—eventually, even pre-K," Berger said.
Currently, OCEARCH is tracking 47 sharks, some of them bull and mako but mostly great whites off the U.S. East Coast and in the waters off South Africa.
Many of the sharks are given endearing names, such as Princess Fi, Genie, Opera, and Sabrina. Others have handles more befitting ships, such as Poseidon, Redemption, Perseverance, and Courage.
Mary Lee, who was tagged off of Cape Cod, is named after Fischer's mother. "My parents have done so much. I was waiting and waiting for a special shark to name after her and this is truly the most historic and legendary fish I have ever been a part of and it set the tone for Cape Cod," Fischer wrote in an online description of Mary Lee.
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 ten 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.
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."
The third tag is an accelerometer package, which tracks fine-scale data on the shark's body movement and behavior along with water depth and temperature information. That tag, which is designed to release from the shark after just two days, records more than eight million data points each day, with the information stored to memory. The tag is embedded in a float package that contains a satellite transmitter and a VHF radio tag, which transmits a ping that can be heard over a ten-mile range with a VHF receiver and antenna.
"In this case, the VHF tag allows us to find the needle in the haystack, once the satellite tag tells us where the haystack is," Whitney said.
Although OCEARCH has been using two-day accelerometer tags, the team off Cape Cod is now going for the longest accelerometer track of a shark ever: two weeks of second-by-second behavioral information.
Finally, OCEARCH researchers attach a PSAT archival satellite tag, which records depth, temperature, and light levels (used for geolocation) and stores the data to memory. The tag is programmed to release from the fin anywhere from six months to a year after being attached. It then floats to the surface and processes and summarizes the data for transmission back to researchers via satellite.
"It'd be great if there was one tag to get all the information, but there's not," Berger said.
The researchers have gotten the tagging procedure down to, well, a science. They've perfected the process by performing it on more than 100 sharks—67 of them great whites.
To date, the largest great white the team has captured and tagged is an 18-foot, 5000-pound animal named Apache. Apache currently holds the world record as the largest fish ever caught and released by anyone, Berger said.
"Florida has more shark incidents than any place in the world, but virtually all of those bites form small sharks—black tips and spinner sharks. In fact, I'm not sure of any confirmed white shark attacks there," Whitney said.