Sharks have been making headlines — and it's not just because Discovery's Shark Week kicked off on Sunday. As conservation efforts have improved, populations have grown, leading to more sightings and incidents. But just because numbers are improving, for now, it doesn't mean sharks are safe from climate change-related threats to the environment in the future.
"[Sharks'] existence is predicated on having these healthy ecosystems, and they help maintain those healthy ecosystems. And so those impacts for climate will trickle through," said Joshua Drew, Ph.D., an assistant professor of vertebrate conservation biology at the State University of New York College of Environmental Science and Forestry.
Shark populations in waters near the U.S. have benefitted from state and federal conservation efforts after overfishing devastated populations. Drew said the prohibitions against shark finning tend to get the most attention because the practice is so brutal. It entails cutting the fins off of live sharks before discarding them back into the ocean and has been banned in the U.S. since 2000. In 2011, The Shark Conservation Act was signed into law to strengthen prohibitions against shark finning. But shark populations have also increased due to other regulations like those that target specific fisheries to reduce bycatch and those that boost populations of prey species including smaller fish and seals.
Grey and Harbor Seals, favored prey of Great White Sharks, swim around the harbor in Chatham, Massachusetts on July 15, 2022. - The coast of Massachusetts is home to many White Sharks during the summer months. With interest in sharks growing, a shark related tourism industry has sprung up in places like Chatham, including sightseeing tours. (Photo by JOSEPH PREZIOSO / AFP) (Photo by JOSEPH PREZIOSO/AFP via Getty Images)
"It is both a combination of the shark protection that they've been afforded," Drew said, referring to white shark populations near Cape Cod in Massachusetts. "It's also the marine mammals have done much better. So there's a lot more seals now, and so, because there's more seals there's more food for the sharks."
This bump in shark populations doesn't mean the creatures are safe from man-made climate change. The changing climate poses myriad threats to marine life. Warming oceans, current changes, acidification, rising seas, flooding, and droughts have had a major impact on marine ecosystems, according to NOAA Fisheries. Sharks as a species tend to be a bit less vulnerable to climate change than other species, according to NOAA Fisheries, but their habits could change in response.
"We've heard a lot about oceanic heatwaves lately, and so if the water becomes super, super hot, sharks can swim easily dozens of miles a day if not much more than that," Drew said.
This mobility means warmer water sharks could start migrating north. Drew predicts tiger sharks and dusky sharks, which have historically been infrequent visitors to New England waters, could become more common in places like New York and Massachusetts. Their migratory habits mean they also follow the food. So as waters warm and become more or less inclement for various prey species, sharks will track them where they go.
"We're starting to see a northward migration of a lot of a fish that are commercially caught, and so southern New Jersey fisheries are starting to look more like Carolina or Delaware fisheries — those things are moving up. And so the sharks that like to eat those fish are just going to follow their prey," Drew.
People enjoy the water at Rockaway Beach, Tuesday, July 19, 2022, in the Queens borough of New York. A number of factors, including warming ocean temperatures, are contributing to an expected proliferation of sharks along the New York coastline this summer. (AP Photo/Frank Franklin II)
Understanding the impacts of climate change on sharks gets more complicated when looking at prey animals, according to NOAA. If climate change or overfishing affects an organism, even way down the food chain, like mollusks or plankton, that could have a disastrous impact on prey higher up the chain and ultimately the sharks themselves.
Fewer sharks might sound comforting to swimmers afraid of an incident. But not only are these sharks absolutely vital to the ocean ecosystem, they can also help to protect against climate change. Yannis Papastamatiou, an assistant professor of biological sciences from the Institute of Environment at Florida International University, said that sharks' appetites can boost the growth of carbon dioxide-trapping plants like seagrass, feeding on organisms like turtles that eat the grass.
"If you have sort of no sharks in some of these areas, sea turtle population, for example, may run amok, and they may actually sort of devastate seagrass beds," Papastamatiou said. "The sharks are actually, by having this sort of indirect effect on the seagrass, can be helping with — mitigate some of this climate change."
Plus, shark attacks — which Drew said are referred to as "incidents" in the scientific community — are still incredibly rare. In 2021, there were 73 unprovoked bites reported globally, according to Florida Museum's Yearly Worldwide Shark Attack Summary. It's a jump from the three previous years, but still in line with the five-year global average of about 72 bites annually.
"The vast majority of times you're in the ocean, you're probably been near a shark and you probably didn't know it because the shark doesn't want anything to do with you," Drew said.
In response to a spate of sightings and incidents around Long Island, New York, state authorities have stepped up surveillance around popular beaches. The Department of Environmental Conservation also released a list of best practices that swimmers, surfers, and waders can take to protect themselves. And Drew had some advice, as well: get an education from respected sources like the New England Aquarium or National Aquarium, and learn to love the shark.
"Don't watch Shark Week. That's only going to exacerbate your fear," he said. "I would say go to aquaria. Learn to take a look at [sharks] when they're on the other side of the glass and really just kind of see how beautiful and magnificent they are."