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In search of bull sharks, where manatees roam

Alyssa Andres, a postdoctoral fellow at Florida State University's Coastal and Marine Laboratory, holds a baby bull shark caught in King's Bay in Crystal River. She's part of a small research team catching these sharks, taking measurements and biological samples, and releasing them back into the water with tags and trackers.
Daylina Miller
/
WUSF
Alyssa Andres, a postdoctoral fellow at Florida State University's Coastal and Marine Laboratory, holds a baby bull shark caught in King's Bay in Crystal River. She's part of a small research team catching these sharks, taking measurements and biological samples, and releasing them back into the water with tags and trackers.

It's 8 in the morning on a warm summer day as we crank up the pontoon boat at Pete's Pier Marina and head out into King's Bay. 

A parade of powerboats roar by in the main channel, heading out to the Gulf of Mexico. This early in the morning, the heat has yet to bear down. The slightly salty air has the aroma of sun block and ladyfish cut into blocks of chum. 

Soon enough, there's a tug on the fishing line. On the other end is a juvenile bull shark. With lots of youthful energy. 

“Oh, you're mad, I know, I get it. So mad, so mad. I know I know I know...,” says Alyssa Andres, the lead scientist on a study of these creatures.

The postdoctoral fellow at Florida State University' Coastal and Marine Laboratory is anything but a dispassionate scientist. She empathizes with the little guys, calling them "baby" and "sweet pea."

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“They're just cool. Actually, wait till you see these babies. They are, in fact, very cute,” she said with a laugh.

Andres puts some chum on a hook and minutes later pulls one of those "babies" out of the river, with the Crystal River power plant's cooling towers as a backdrop. They are about 2 feet long, with a sandpapery skin reminiscent of a sting ray.

And yes, they are cute.

“This is way too big for her. Just the applicator,” she says. “She's so little, so little. This is the smallest one is it? I think so. Just looking beautiful.” 

They take measurements, weigh her, take a biopsy after checking for parasites and release her back into the river. 

“All right, little one. You ready to go?” she ask the shark. “Come on baby go, go, go. Oh E on the release E on the release looks amazing."

That's "E" as in excellent.

Why do bull sharks migrate here?

The second largest spring system in the state is the palette for this study. Andres and her boyfriend, Harrison Clark, are both researchers at FSU, and do this on weekends as a part-time gig.

What they're trying to do is create a baseline understanding of what's here and what we expect to find in the future.

And like many things in nature, it ties into climate change.

Bull sharks are cold-sensitive. Even though they're found throughout the Gulf, the females use estuaries such as Crystal River for nurseries. The constant 72-degree water keeps them warm during cold snaps. But as ocean temperatures rise, scientists want to find out how far north they are migrating.

“And so we think that springs habitats might provide a better, more stable habitat across the year,” Andres said. “And certainly as waters continue to warm or fluctuate temperature, we think that this might be a really interesting area different from all the other known nurseries.” 

They've inserted radio tags in 14 sharks to date, but more have been outfitted with passive identification called “spaghetti tags." They've taken measurements and tissue samples from 44 sharks in the past year.

Funding for their research comes from proceeds from the state's "Protect Florida Springs" specialty license plates through the Fish and Wildlife Foundation of Florida.

"We were thrilled to award two grants to Alyssa and her team for this important project," said Andrew Walker, president & CEO of the Fish & Wildlife Foundation of Florida. "Their work will provide invaluable insight into how bull sharks are using Crystal River, providing guidance for future conservation efforts."

They're also pairing with Minorities in Shark Sciences to be able to provide opportunities for minorities in STEM fields to be able to participate in this research.

Florida State University researcher Alyssa Andres and Harrison Clark gently hold a baby bull shark in place while they insert a water tube to help it breathe while on the boat.
Daylina Miller
/
WUSF
Florida State University researcher Alyssa Andres and Harrison Clark gently hold a baby bull shark in place while they insert a water tube to help it breathe while on the boat.

It's all on a shoestring budget, however. Their pontoon boat is owned by a relative of Harrison Clark, Andres' boyfriend and the lead field technician for this study.

They got involved when they were at his family's riverfront home a couple of years ago, and saw a fisherman hooking a shark. Clark yelled out to them about its size and weight, and a light bulb went off in his head about doing a study.

'An incredibly special ecosystem'

This is personal for Clark, who’s a native of Crystal River.

“If we can kind of establish that this is another species that relies on this system. It's kind of another arrow in the quiver for springs conservation as a whole as well, not just shark conservation,” he said. “As these places kind of get more and more developed, it's a kind of a key intersection of conservation and education.”

Added Andres: "Harrison grew up here, was able to share this beautiful place with us and our friends. And this is being the second largest spring system in the state. It's such an incredibly special ecosystem. And so for us, to be able to add any kind of knowledge to our understanding of this ecosystem means so much to us from a conservation standpoint and from somebody who's loved and lived and recreated in these waters — certainly his whole life — and in the time that I've known him, it means a lot to us."

The sharks reach about 10 feet when fully grown. The ones we're after this summer morning are only about 2 feet long.

They are the only shark species that can tolerate long periods of freshwater exposure, sometimes venturing hundreds of miles inland via coastal river systems.

"We take blood samples, we take a small, little trailing edge of their fin for genetics, we take a small muscle biopsy for chemical analysis and we tag and then we, if possible, take parasite samples and teeth samples also for chemical composition and for health analysis for these animals," Andres said.

They're also asking for help from anyone who ventures into these waters.

"We're asking members of the public in Crystal River and Kings Bay to report to us when they catch a bull shark and we're involving them in the data collection process," she said. "So it's trying to get the community involved in this data collection and for us to kind of pull back that proverbial veil, so to speak, on what it is that we as scientists do and what this information is used for."

She said preliminary results show the bull sharks are gravitating to the springs in the winter and during cold snaps. And they're sheltering as far away from coast as they can get.

A new research study published in the “Journal of Animal Psychology” found that the juvenile bull shark population had increased fivefold from where it was 20 to 30 years ago in Mobile Bay, Ala., and in several Texas estuaries — an increase scientists attribute to climate change — and one is likely occurring in estuaries along Florida’s Gulf Coast, like Crystal River.

Harrison Clark guides his family's pontoon boat along the Crystal River, with the power plant's cooling towers as a backdrop
Steve Newborn
/
WUSF Public Media
Harrison Clark guides his family's pontoon boat along the Crystal River, with the power plant's cooling towers as a backdrop

Copyright 2024 WUSF 89.7

Florida State University researchers Alyssa Andres and Harrison Clark cast fishing lines into Crystal River with hope that they'll hook some baby bull sharks to study.
Daylina Miller / WUSF
/
WUSF
Florida State University researchers Alyssa Andres and Harrison Clark cast fishing lines into Crystal River with hope that they'll hook some baby bull sharks to study.
Andres and Clark use a pair of pliers to carefully remove a hook from a baby bull shark's mouth.
Daylina Miller / WUSF
/
WUSF
Andres and Clark use a pair of pliers to carefully remove a hook from a baby bull shark's mouth.
Andres and Clark insert a small water tube into the bull shark's mouth to stimulate its gill and help it breathe while on the boat.
Daylina Miller / WUSF
/
WUSF
Andres and Clark insert a small water tube into the bull shark's mouth to stimulate its gill and help it breathe while on the boat.
Andres and Clark and an intern prepare to take a blood sample from the bull shark.
Daylina Miller / WUSF
/
WUSF
Andres and Clark and an intern prepare to take a blood sample from the bull shark.
Andres takes a small blood sample from the bull shark.
Daylina Miller / WUSF
/
WUSF
Andres takes a small blood sample from the bull shark.
Clark takes a tooth sample from the bull shark. It will easily grow back the lost tooth.
Daylina Miller / WUSF
/
WUSF
Clark takes a tooth sample from the bull shark. It will easily grow back the lost tooth.
Andres snips off a tiny sample of fin from the bull shark.
Daylina Miller / WUSF
/
WUSF
Andres snips off a tiny sample of fin from the bull shark.
Andres and Clark gently straighten the bull shark out and take measurements of its size.
Daylina Miller / WUSF
/
WUSF
Andres and Clark gently straighten the bull shark out and take measurements of its size.
Andres and Clark continue their measurements of the bull shark.
Daylina Miller / WUSF
/
WUSF
Andres and Clark continue their measurements of the bull shark.
Andres makes a tiny incision and inserts a spaghetti tag into the shark in case it's caught again. This bull shark is not big enough for an electronic tracker implant.
Daylina Miller / WUSF
/
WUSF
Andres makes a tiny incision and inserts a spaghetti tag into the shark in case it's caught again. This bull shark is not big enough for an electronic tracker implant.
Alyssa Andres and Harrison Clark take smartphone video of the bull shark to capture its condition before they release it.
Daylina Miller / WUSF
/
WUSF
Alyssa Andres and Harrison Clark take smartphone video of the bull shark to capture its condition before they release it.
Andres and Clark did not capture any bull sharks big enough today to implant these small, electronic trackers that can last for years.
Daylina Miller / WUSF
/
WUSF
Andres and Clark did not capture any bull sharks big enough today to implant these small, electronic trackers that can last for years.
Andres shows off the equipment used to communicate with electronic tracker implants inserted into the bigger sharks.
Daylina Miller / WUSF
/
WUSF
Andres shows off the equipment used to communicate with electronic tracker implants inserted into the bigger sharks.
Andres holds a homemade net that she has placed the bull shark into to make its release easier on both of them.
Daylina Miller / WUSF
/
WUSF
Andres holds a homemade net that she has placed the bull shark into to make its release easier on both of them.
Andres gently releases the bull shark back into Crystal River.
Daylina Miller / WUSF
/
WUSF
Andres gently releases the bull shark back into Crystal River.
The bull shark happily swims through the water after its release.
Daylina Miller / WUSF
/
WUSF
The bull shark happily swims through the water after its release.

Steve Newborn is WUSF's assistant news director as well as a reporter and producer at WUSF covering environmental issues and politics in the Tampa Bay area.
Daylina Miller, multimedia reporter for Health News Florida, was hired to help further expand health coverage statewide.
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