Shark Tagging

More than a dozen different types of sharks live off the North Carolina coast. Researchers with the UNC Institute of Marine Sciences have caught and studied them since 1972, creating one of the largest databases of coastal sharks in the nation.

BEAUFORT — The small shark came out of the water, hooked on a line. 

The deckhand carefully pulled the hook out of the shark’s mouth and handed it to the marine biologist.

“Female, sharpnose,” called out Dr. Steve Fegley, Adjunct Research Associate Professor at the University of North Carolina Institute of Marine Sciences, as he carried the shark over to the examination table. “Tale to nose stretch is 92.”

It’s all part of one of the longest running studies of coastal sharks in the country. After jotting down the numbers, graduate student Danielle Keller took an instrument that looked very similar to a spear, punched the tip into the shark’s thick skin and then quickly pulled it out, which left a plastic tag attached to the creature. Then, Dr. Fegley sent the shark back into the water.

“Shark in the water,” Dr. Fegley added, as he looked over the boat railing at the shark now swimming away. “She’s happy now.”

Researchers from UNC Institute of Marine Sciences have caught, examined and released sharks in the same way, and in the same locations off the coast of North Carolina, since the study of coastal shark populations began in 1972.

“Every shark we sample, we’re getting measurements from them and its all going into a database that we can look at to see how their populations are doing over time,” says Keller, as she readies another tag to apply to the next shark that is brought up. “Every shark we collect is making a difference."

Keller also admits getting face to face with any shark, even a smaller shark, is a thrill.

”Just having the up-close perspective to see these guys, a couple inches from their face, looking at their eyes and shape of their body is pretty interesting to me,” adds Keller.

UNC IMS shark tagging researchShe doesn’t have long to look at the shark because the study process is precise and efficient. A shark can’t survive out of the water for long because water must flow over its gills for it to breath. But in 45 seconds or less, researchers identify the shark and determine its sex. The shark is then examined, measured, and tagged. The tag is inserted just under the shark’s thick skin so the creature isn’t harmed.

“When you do this continuously, paying attention so you do it in the same way so the data collection is consistent across time, it provides an extraordinary ability to see those ups and down, and at a scale that matches the lifespan of these organisms,” explains Dr. Fegley. “Studies of this size are unique and difficult and rare, but it gives you a real sense for what’s happening. In addition, when you have changes and those changes take place over decades, you can only make sense of them if you follow them over decades.”

The research voyages have followed the same routine since the beginning. Before any research is accomplished, the scientists become fishermen. Fresh fish is caught and the hooks are then baited. Whatever fish are not used are released and then the lines are deployed.

“It’s exciting because you never know what you are going to see,” says Stacy Davis, Facilities Manager at UNC Institute of Marine Sciences, who has worked as a deck hand on the research boat for 20 years. Davis and two other crewmembers are sending out the fishing line. After five hooks a floatation buoy is attached to the line.

“We put long lines out, about 100 hooks on each line, and the hooks hang deep, mid range, shallow, so you are fishing a good part of the water column,” says Dr. Fegley as he watches the line go out.

The first sampling location is about one mile off Shackleford Banks, in about 35 feet of water. The second location is roughly seven miles farther out to sea where the water is about 70 feet deep.

The line is brought in after an hour and the science begins. Thirty-eight species of sharks have been identified off the North Carolina coast in the nearly 45 years the project has been tracking offshore shark populations. Scientists say so many species of sharks are found here because the state is located at the edge of the Mid-Atlantic and sub-tropic currents. Those currents bring plenty of fish to the area and an abundance of food attracts plenty of sharks.

Marine Ecology Research Technician Emily Pickering watched as another sharpnose shark is brought in for examination.

“I think the most fascinating thing to me is how long they’ve been around, they’re perfectly made for this environment, they’re just perfectly made,” says Pickering.

The study runs from May through October. That’s when the water warms and coastal migrations bring the most fish to the region. Sea turtles are also hatching during this time. Once again, an ample food supply brings more sharks. But overall, the study finds shark populations are not doing well.

“The great sharks, of which we have 11 species of major great sharks off the coast, have all shown dramatic declines on the order of 87% and 96%,” says Dr. Pete Peterson, Alumni Distinguished Professor of Marine Sciences, Biology and Ecology at the UNC Institute of Marine Sciences.

Dr. Peterson says fishing for sharks and the fish species that sharks count on for food is believed to have caused the dramatic decline in the numbers of great sharks. Researchers expected to find that as the numbers of great sharks declined, the populations of smaller sharks would increase. That’s because the larger predators no longer pose a threat. But the survey is finding the population of smaller sharks is dropping too.

“The record reveals that abundances are down for all species of sharks,” says Dr. Fegley, as he finishes examining another Atlantic Sharpnose and sends it back into the ocean. “For the great sharks — such as the hammerhead, bull and tiger shark — the numbers are down dramatically but the numbers are down for the intermediate sizes as well.”

He cites the Atlantic Sharpnose as an example. While there are more Atlantic Sharpnose sharks found off the coast than there were in the 1970s and 80s, the numbers are not making up the difference in the loss of the great sharks.

Scientists don’t know why the entire shark population is dropping, or what is bringing sharks so close to shore — and into contact with swimmers — this summer. The survey continues with the broader question being asked. Is the decline in shark populations a sign of deeper problems in the ocean?

"Sharks are the top predator in the food chain, and they are a good indicator if we are trying to figure out if something is wrong,” adds Dr. Fegley. “And from this information we can gain information not just about the individual populations of sharks but it is one more way we can get a look at the coastal ecology and how it is changing.”


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