UNC researchers and crew members aboard the Institute of Marine Sciences’ research vessel relax in the sun as Atlantic Ocean waves gently sway the boat. Two of them discuss recent fishing regulations. In the wheelhouse, the captain and another crew member argue over the best chili recipes.
An hour passes with ease, and suddenly it’s time to get to work. Two crew head to the back of the boat and start pulling up the one-kilometer line, dotted with 100 hooks. It doesn’t take long before they find what they’re looking for.
“Shark!” exclaims crew member Stacy Davis. In one swift motion he unhooks the animal and hands it to Institute of Marine Sciences Assistant Professor Joel Fodrie. The species and sex are identified and it is measured, tagged and photographed. In less than a minute, it’s tossed back in the water. Years of experience on board have created this efficiency.
Carolina professor Frank Schwartz began surveying sharks in 1968. After exploring different methods and locations, the IMS shark survey officially started in 1972. It’s unsurpassed in the U.S. for its consistency and longevity.
“When it started, I don’t think the goal was to have something that’s now decades long. I don’t have the sense there was even a three- or five-year plan,” says Fodrie, now the research lead for the survey. “The times were different. The world hadn’t really woken up to the important role that sharks play in ecosystems.”
In addition to being crucial top predators, sharks are also indicator species — their abundance and health provide information on the overall condition of the ecosystem. Scarcity of food, habitat degradation, noise pollution and poor water quality affect shark populations and indicate that species lower on the food chain are also struggling.
“If you have a lot of sharks you can probably be confident the ecosystem has good productivity to be able to support that,” Fodrie says. “If the system were to be out of whack, we would see big swings in shark numbers because they’re depending on those resources.”
While there are still lots of unknowns when it comes to these animals, only a fraction of today’s knowledge had surfaced in the 1970s. Back then, researchers concentrated on basic topics like identifying local species and maximum size.
“The merit in these programs really show themselves retrospectively, once you get a couple decades in and can start looking back,” Fodrie says.
In reviewing decades of data, researchers have been able to identify important trends. In the ’70s and early ’80s, for example, there was a higher diversity of species. Those that declined or disappeared tended to be medium-to-large species. Around that time, both commercial and recreational shark fishing was abundant in North Carolina. By the 1990s, regulations became stricter and in the last decade some of those species have returned.
While regulating fishing has helped shark populations, Fodrie says its more complicated than that. For example, a recent study shows that the average and maximum size has been declining across all species — even those on “no take” lists.
“Fishing is probably a big part of it because it’s not only the sharks that get fished but also things that the sharks eat. But it’s hard to lay all that on the feet of fishing,” he says. “We’re in a world with lots of forms of change. There’s temperature change, habitat change, changes in human activity, soundscape change. Those all contribute to what we see. It’s a complex system.”
While it may not take long for shark populations to be affected by these changes, it can take decades for them to recover. Fortunately, the IMS shark survey will be producing data for years to come, thanks to the expertise and dedication of staff, students and researchers.