ASU scientists hatch an egg-shaped tracker to study pregnant sharks and keep them alive

For a long time, scientists who wanted to know whether a shark was pregnant had one real option.

They would capture the shark, log the location and dissect it. That meant killing the expectant mother. And they’d still never know for sure where she was going to give birth, leaving a mystery forever lost beneath the waves.

That was a problem, as was the act of killing endangered or threatened species for data. So a group of ASU scientists and their collaborators set out to solve it.

First, as often happens with sharks, they needed a bigger boat. They also needed a portable ultrasound, a 3-foot-long device that works like a tampon applicator and a tiny tracker shaped like a chicken egg.

What they ended up with was a new satellite tracking technology, implanted in the uteruses of pregnant sharks, to help biologists better understand where the sharks give birth and how humans can protect their vulnerable young.

ASU doctorate candidates Brooke Anderson and Beckah Campbell, among the other researchers, endured choppy seas, smelly chum and the uncertainty of testing out new technology to help make the research possible.

Their efforts ultimately contributed to a paper, out this month in Science Advances from coauthors James Sulikowski, an ASU professor, and Neil Hammerschlag, an investigator with the Marine Biodiversity Observation Network.

Their work is a “very cool paper that opens up a number of interesting science questions,” wrote David Curnick, head of the Ocean Predator Lab at the Institute of Zoology in the Zoological Society of London who was not involved in the study, in an email.

It’s all part of a larger story, one that has been playing out over many years, of the aquatic animals that inspire fear and admiration in many humans and the hopes of some land-based advocates to better preserve a species necessary for the health of Earth's oceans.

“It’s just really exciting to not only protect the moms, but to get to protect this next generation of sharks before they're even born,” Campbell said. “It's really game-changing for shark science.”

Birthing a new tracking device

Scientists have been tracking sharks with tags, a kind of expensive, waterproof bling, for a long time. But with that technology, they could only estimate when and where the sharks were giving birth. They couldn’t get an exact location.

To solve that problem, Sulikowski and Hammerschlag came up with an idea: a tracker with a special sensor that could tell whether it was wet or dry.

Shark reproduction is complicated — sharks, for instance, have two uteruses — but the key point here is that baby sharks need a wet environment to survive.

So if a buoyant wet/dry sensor were placed in utero along with the shark pups, the researchers reasoned, it could be programmed to tell them when it was “born” and floated to the surface. And such a sensor would be relatively non-invasive. It wouldn’t hurt the sharks, as long as the researchers could use the tampon-like applicator to insert what's called a birth-alert-tag.

But it wasn’t guaranteed that the tags would work. Deploying the devices is full of challenges to begin with. The equipment can break, batteries can die, software can malfunction.

Despite completing as many tests as they could in a lab beforehand, at first, that’s exactly what happened. The team, including former ASU graduate research assistant Hannah Verkamp, scoured the ocean for mother sharks, hauled them toward the boat, performed the requisite tests and deposited their tracking eggs as planned, 10 to begin with.

The sensors on nine of those 10 tags wouldn't communicate with their microprocessors, due to a firmware issue.

One tiger shark did carry her tag for almost six months, but her external tracker failed three months before the tag told researchers she had given birth in 2019 at a known gestation site. Still, that was a promising sign: the tag, at least, had worked with one shark. They just needed to prove it could work with others, in tandem with the other trackers.

The team regrouped and fixed the software problems in the birth-alert-tags, but the next batch of tracker eggs revealed a battery life problem, along with an internet connectivity problem (as it turns out, an antenna can only bend so much before it breaks).

That’s when they were “starting to second guess ourselves,” Sulikowski said. They started to think maybe it wasn’t going to work, that the whole idea had been ridiculous to begin with.

Then came the surprise shark.

‘Like Christmas,’ complete with the wait

It was a cold day in the Outer Banks. Anderson and Campbell remember layering up in the twilight, trying to keep warm aboard the Reelebugging, the bigger boat and one that happened to belong to Bobby Earl, known for his adventures on "Wicked Tuna: Outer Banks."

Sulikowski had reached out to Earl’s girlfriend and first mate, Aimee Perkins, a diving instructor and certified boat captain, to see if the team could charter Earl’s vessel. They needed something bigger, because they were setting out to track down some of the biggest sharks of them all: great whites, for a special that would later air on the Discovery Channel’s Shark Week. (Sulikowski noted that the financial backing that comes from Shark Week makes a big difference when you’re trying to equip a single shark with as much as $5,000 of tracking equipment.)

But Earl, a Long Island financial planner and avid angler turned longtime commercial bluefin tuna fisherman, wanted nothing to do with the research. He had a successful business, and the last thing he wanted to do was intentionally catch sharks.

“(Shark fishing is) probably the sloppiest business on earth,” Earl said. “You have to make a stew of slop and guts and chum and your boat just stinks and the flies are everywhere. It's horrible.”

Still, Perkins persisted. It was a slow season for them, and it may be a waste of time and bait, but if it meant more time out on the water, why not?

And that’s how the motley crew found themselves shivering in the March air, waiting for something to bite.

The real excitement ultimately wasn't for the juvenile great white they captured — and even Earl had to admit that was pretty amazing — but for something else they reeled in.

A scalloped hammerhead. A female.

The crew rushed into action. They set up an aerator, a device that keeps water over the shark’s gills. Anderson grabbed the ultrasound machine while Campbell started doing blood work. They shouted to one another: “she’s pregnant!”

“It’s just such a surreal moment when you're looking at that ultrasound screen and you see a baby in there,” Anderson said. “This little baby shark, it's got several months, but soon it's going to be out there in the ocean. And it's just amazing.”

They didn’t waste any time after that. They fastened on tags, inserted the tracking device and prepared to release her.

Then they waited. For six weeks.

Sure enough, in mid-May, Anderson and Campbell, working on campus, got a text from Sulikowski. Their hammerhead had made a beeline for the coast, and then — just as they had planned — the tracking device had bobbed to the surface, announcing the birth of the pups.

From there, they were able to successfully track the mother’s movements back out to sea. Their device had worked.

“We spent six years developing this tag. If it doesn't work now, it’s time to give it up,” Sulikowski said. “But because it all came together like that, it really felt like Christmas…it was such a relief, so exciting.”

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Studying without sacrificing

Before the hammerhead or the tiger shark, before any of the high-tech intrauterine tracking or high-seas searching, there was a controversy.

Two decades ago, Hammerschlag said, few scientists had batted an eye about sacrificing sharks for research. It was considered part of the process, a difficult process, one akin to searching for a highly mobile needle in a marine haystack.

But as Hammerschlag pointed out, you wouldn’t kill an endangered rhino just to see if it was pregnant. Why, he and a few others had wondered, would you do the same with an undersea species?

Hammerschlag didn’t want to give up on improving the field, which is why he reached out to Sulikowski and asked for his help to write a paper, a call to action for scientists to devise a non-lethal means of tracking pregnant sharks.

The reception to that paper, published in 2011, wasn’t all positive, according to Hammerschlag. He says some shark conservationists likened them to oceanic tree huggers, and claimed their work might be counteractive to advancing urgent shark science.

Hammerschlag understood those critiques, but he and Sulikowski believed there were ways to push the boundaries of what was possible. A decade later, after so much trial-and-error developing tags for pregnant sharks, he says, the project proves that it’s feasible to develop more humane methods of studying marine animals.

“Certainly there was, I think, major technological challenges,” he said. But maybe, he added, there was “perhaps less effort to come up with the technology just because…there’s less love of fish, let alone with fish that I think are misunderstood.”

That labor of love has led to a significant advancement in the field, one that “no one else was crazy enough” to attempt, said Jodie Rummer, a professor of marine biology at James Cook University in Townsville, Queensland, Australia. Rummer, who knew Sulikowski in the past through mutual students and who started officially collaborating with him in late 2022, said this research represents a missing link that has been sorely needed in shark research.

“This is a global first,” she said. “It really emphasizes the importance of all of us coming together…(scientists with different expertise and perspectives) do need to collaborate.”

That’s something Hammerschlag thinks is true for coastal populations and landlocked locals.

“Whether you know it or not, no matter where you live, (you are) connected to the ocean,” said Hammerschlag, who also mentioned sharks’ importance to maintaining the healthy ecosystems that drive global economies, food systems and recreation areas.

But for him, protecting sharks is about more than any financial case. It’s about preserving the beauty and wonder of the oceans, and the miraculously evolved predators that roam its depths.

“Even just knowing these animals exist,” he said, “makes the planet a more exciting place.”

Melina Walling is a general assignment reporter based in Phoenix. She is drawn to stories about interesting people, scientific discoveries, unusual creatures and the hopeful, surprising and unexpected moments of the human experience. You can contact her via email at mwalling@gannett.com or on Twitter @MelinaWalling.

This article originally appeared on Arizona Republic: Researchers made trackers for pregnant sharks that work like tampons