A large great white shark paid a visit off the coast of Nantucket on Friday. OCEARCH researchers confirmed this is the largest male great white shark that they tagged in the Western North Atlantic. He measures 13 feet nine inches long and is an estimated 1,653 pounds.
OCEARCH, the nonprofit organization dedicated to ocean research and conservation, says that Contenders visit near Nantucket is not surprising.
John Tyminski, data scientist with OCEARCH, regularly observes Contenders' movements. Contender was first tagged in January off the coast of Georgia and Florida, which is expected of their overwintering season. Even though their location is predictable, tagging a great white shark comes with challenges.
“Contender’s tag was not done on our ship. This was done on a smaller vessel. Dr. Newton and her team went out about 100 miles,” Tyminski said.
“Normally, we use a large ship with a hydraulic lift that comes off the side. So, we’re able to bring the shark on top of this lift, and then do things like blood sampling…In this case, they’re working on a smaller vessel with an almost fourteen-foot white shark from the side of the boat. Drawing blood, performing a small surgery to insert an acoustic tag into the gut cavity. That’s not easy to do,” he added.
Dr. Tyminski said it’s important that they tag great white sharks to observe their reproductive cycle and preserve their population.
“There’s a couple of things that’s important about Contender. He’s a mature male. The fact that he’s the largest is kind of inconsequential… If we want to protect great white sharks, in this case, knowing when and where they reproduce and mate is important,” Tyminski noted.
The OCEARCH team collects blood samples and measures testosterone levels from great white sharks through a tagging and data collection process. “Spot tags are a type of satellite-linked tag. We mount them to the first dorsal fin of the shark. They basically have what’s called a wet dry sensor built into them,” he said.
Tyminski explained that as soon as the shark breaks the surface, and that tag becomes dry, the tag immediately starts transmitting. It transmits about every 60 seconds. Another tag type is an acoustic tag which gets surgically implanted into the gut cavity and allows the shark to get detected by any of the underwater listening stations along the coast. The tags mostly share location data.
“There’s a third special tag that Contender received called a pop-up satellite archival tag… We can program a tag like that to detach after a certain number of days,” Tyminski said.
The team programmed Contenders pop up tag to detach after 170 days. On July 7th the tag came off and began transmitting a summary of the data that it archived.
“The pop-up tag tells us what he’s doing below the surface, and I can already tell you that he’s spent a lot of time at depth. He went down at least 700 meters during his 170-day trek,” Tyminski shared.
