New DNA technology helps identify shark species in fatal attack
Researchers believe 14-foot tiger shark attacked Robin Warren
Swabbing for cells left in the 17-inch bite marks on a surfboard, researchers tapped into new DNA technology to determine that a 14-foot tiger shark was behind the fatal attack on 56-year-old Napili man in Honolua Bay this month.
Lead researcher and renowned shark expert Carl Meyer said that in the past, scientists have had to rely on observations by the victims or bystanders to help identify the shark in an attack. In Hawaii, the species goes unidentified in about 40 percent of incidents.
“There’s a lot we don’t understand about shark bite incidents,” Meyer said in a taped statement released Friday. “And so we’re trying to get as much factual information as we can in order to, first of all, make sure that we’re able to inform ocean users to the greatest extent possible about risk of their activities, and also hopefully, in the future to find ways to reduce the risks.”
Robin Warren of Napili was paddling out from the old ramp in the bay when he was attacked in the early morning hours of Dec. 8 prior to the start of a women’s professional surfing contest.
Warren was taken to Maui Memorial Medical Center for surgery but died from his injuries the next day.
Adam Wong, a Maui-based education specialist with the state Department of Land and Natural Resources’ Division of Aquatic Resources, said that Meyer provides swab kits that he and his colleagues use when there are shark incidents. The police department still had the surfboard in their locker and agreed to let Wong swab it. The samples had to be kept at cold temperatures to keep the DNA from degrading, said Wong, who then shipped it over to Meyer.
Wong said it was the first time they were able to use the process.
Relying on clues left on the board and witness accounts, officials have been able to guess the size and species of shark in some past attacks; DLNR keeps a public list of shark incidents with the type of species that they believe were involved.
However, the rise of DNA technology has helped them get a lot closer.
Derek Kraft, a University of Hawaii Sea Grant Fellow working at UH’s Hawaii Institute of Marine Biology, said that when a shark bites onto something, it leaves behind a sticky mucus layer that can last for some time. Warren’s board wasn’t swabbed until 2 1/2 days later.
“So we swabbed the mucus off, and within that there’ll be cells,” Kraft explained in a taped statement. “We can extract the DNA and sequence it. And that sequence is just like a barcode, like when you go to the grocery store and you grab an item off the shelf and you scan it.”
Kraft said that researchers have databases with DNA codes that can be matched with a certain species. By looking at “the DNA barcode,” they can tell what type of species the cells came from. The databases are massive and even include sequences for cookie cutter sharks, which have only been documented in a handful of bites, Kraft said.
“We have tested this method on wetsuits as well, and been able to get DNA barcodes off that,” Kraft said. “We’ve also tested it on fish. So, when fishermen bring in a fish with a big bite out of it, we’ve been able to swab it and actually get the DNA barcode separate out between the fish and the shark. So, from what we’ve tested so far, we do think this method would work on just about any medium.”
While the bite marks on Warren’s board helped determine that the shark was about 14.3 feet long, the leftover DNA was the clincher in discovering that the animal was a tiger shark.
“We are absolutely certain that it was a large tiger shark (in the 98th percentile for size), that bit this man,” Meyer said.
Kraft said in the future, researchers could possibly connect attacks to individual sharks.
“The swabbing technique is capable of grabbing the DNA,” Kraft said. “And within there we could use it to find the individual. We haven’t developed the techniques for that yet. It would take some groundwork to kind of build a database of tiger sharks. And then from there, we get a better idea of what the population’s genome looks like. And we could use that information to identify individuals.”
Kraft said the technology exists — it’s used with bear attacks in Alaska, for example — but hasn’t been applied to sharks.
Wong added that while the gains in DNA sampling are encouraging and a useful tool in providing closure to a case, it doesn’t distract from the tragedy of what happened at Honolua.
“Our aloha and love goes out to the surfer and his family during this time, especially during the holiday season,” Wong said. “Even though we’re able to, to move forward with such scientific gains, you know, I do take a step back and just wanted to send our condolences.”
As a waterman who’s always in the ocean with his kids, Wong said the attack was a sobering reminder that “it really can happen to anybody.”
“This past incident really hit home when he was a surfer, and you know, me and my family, we all surf a lot, and I really took this to heart,” Wong said. “With this type of information, you know, moving forward, hopefully this will help us educate the public.”
* Colleen Uechi can be reached at firstname.lastname@example.org.