Sharks, Dolphins and Turtles Are Turning Up In Strange Places Because Of Climate Change

Luke Halpin couldn't believe his eyes. In the early morning hours from his spot on a research ship in the Pacific Ocean, he was seeing bottlenose dolphins. If Halpin had been on a ship off the coast of California, this wouldn't be remarkable. But he was on a Canadian research vessel floating about 100 miles northwest of Vancouver. These dolphins had never been seen alive north of the waters off the coast of Washington state.

"My initial reaction was one of disbelief," he told Newsweek. "But they're an unmistakable species. They're easy to identify."

Halpin's next reaction was to start counting and pull out his camera. In total, he spotted about 200 dolphins and 70 false killer whales—a very large group—that came within a few hundred feet of the ship. He and his colleagues published their observations in Marine Biodiversity Records on Thursday. (Halpin ran a marine biology consultancy; in January, he began a PhD program at Australia's Monash University. The expedition was funded by Canadian government programs.)

Sightings like Halpin's—that is, dolphins and other creatures like swordfish and loggerhead turtles finding themselves out of their usual waters—may become more common as ocean temperatures continue to rise. Bull sharks may also be establishing nurseries in new areas along the North Carolina coast further north than they're typically found. And more and more sea turtles are also stranding themselves near Cape Cod, Massachusetts, hundreds of miles away from where turtles usually run into trouble.

luke halpin bottlenose dolphins
Luke Halpin and his colleagues found bottlenose dolphins off the coast of British Columbia, Canada in July 2017. Dolphins have never been seen that far north—and they aren't the only animals that appear to be moving north as waters warm. Courtesy of Luke Halpin

In some cases, these shifts are clearly tied to a change in the environment. In a paper published Monday in Scientific Reports, Chuck Bangley, a postdoctoral researcher at the Smithsonian Environmental Research Center, and his colleagues analyzed data from the North Carolina fisheries' department, which compared the temperature, oxygen and salinity of the water to the number of sharks near Pamlico Sound, part of the stretch of water between the islands of the Outer Banks and the rest of the state. Young bull sharks were almost never found in the area before. Only six had been found in the sound between 2003 and 2011. But since 2011, there seems to have been a "bull shark switch" that got turned on, Bangley said—and the number of juvenile sharks found increased dramatically to 53 between 2011 and 2016.

"What seems to be happening is that the temperatures have increased in the sound, and it's brought the sound in the comfort zone for bull sharks to give birth and for the juveniles to grow up for that first summer," Bangley said.

It's possible that sharks born in these new, northern nurseries may return in a decade or two as adults to give birth themselves—increasing the number of adult bull sharks in the area over the summer. That could have serious ramifications for humans. Bull sharks are considered the third-most dangerous to humans, Bangley said. More sharks in an area could mean more opportunities for sharks and humans to meet. Warmer climates could also bring more humansto the seashore for relief, Bangley notes, which is probably more likely to be connected to any increase in beach-related injuries than the sharks.

Further up the Atlantic coast, Bob Prescott, the director at Mass Audubon's Wellfleet Bay Wildlife Sanctuary on Cape Cod have also noticed a change. Typically, Prescott said, stranded turtles would turn up around the Long Island Sound off the coast of New York and Connecticut. But as New England waters get dramatically warmer, the turtles may be moving further north—which might be why Prescott has seen more and more turtles stranded on beaches along Cape Cod instead. (The increase in strandings may have less to do with temperature than with the fact that there are just more turtles around as the populations recover, Prescott cautioned.)

It's still too soon to say if dolphins, sharks and turtles will consistently establish themselves in warming northern waters. But Halpin says it's possible that might happen in the future—especially if we don't change the temperature trends we're seeing today.