Scientists Can Tell If Great White Sharks Are Around by Testing DNA in Seawater

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Love the beach but fear sharks? Your risk of dying in a shark attack is infinitesimal—roughly 1 in 3.7 million—but it’s still a risk nonetheless. Scientists say white sharks are becoming more prevalent along California’s coast thanks to federal protections, and on the opposite side of the country, Cape Cod recently saw its first fatal shark attack in more than 80 years.

A new proof-of-concept study, published in Frontiers in Marine Science, could shed new light on what's lurking beneath the surface. Researchers from UC Santa Barbara, the U.S. Geological Survey, and partner universities theorized that environmental DNA (eDNA)—an organism's cast-off bits of genetic material—could show the presence of white sharks in a particular part of the California coast.

White sharks forge distinctive trails by shedding skin and discharging mucus, feces, and other genetic markers in seawater. Researchers created a species-specific test for white shark eDNA, then rode stand-up paddleboards to four sites beyond the line of surf to collect water samples. After analyzing the samples in the lab, they found white shark eDNA in two samples from areas where the fish were known to gather, and no eDNA in the other two samples from sites where sharks hadn't been observed. The results from the preliminary experiment showed that the new test could accurately identify the sharks' eDNA—and that might save a surfer in the future.

"One of the goals of this research is for a lifeguard to be able to walk down to the shore, scoop up some water, shake it, and see if white sharks are around," Kevin Lafferty, lead author of the study, said in a statement.

The use of eDNA has some limitations. Ocean currents can cause eDNA to drift, and that genetic information can degrade quickly in the surrounding environment. “Another challenge is that eDNA might persist in the ocean environment for days, meaning a positive detection might indicate a species that is no longer locally present,” the researchers write in their paper. Still, they say the development is a step in the right direction for better shark monitoring and conservation efforts.

Australian Island Wants Visitors to Stop Taking Wombat Selfies

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iStock.com/LukeWaitPhotography

Spending a day observing Australian wildlife from afar isn't enough for some tourists. On Maria Island, just off the east coast of Tasmania, many visitors can't resist snapping pictures with the local wombats—and the problem has gotten so out of hand that island officials are asking people to pledge to leave the cute marsupials out of their selfies.

As CNN Travel reports, the Maria Island Pledge has been posted on signs welcoming visitors to the national park. It implores them to vow to the island to "respect and protect the furred and feathered residents." It even makes specific mention of the wombat selfie trend, with one passage reading:

"Wombats, when you trundle past me I pledge I will not chase you with my selfie stick, or get too close to your babies. I will not surround you, or try and pick you up. I will make sure I don’t leave rubbish or food from my morning tea. I pledge to let you stay wild."

The pledge isn't a binding contract guests have to sign. Rather, park officials hope that seeing these signs when they arrive will be enough to remind visitors that their presence has an impact on the resident wildlife and to be respectful of their surroundings.

The adorable, cube-pooping wombats at Maria Island are wild animals that aren't accustomed to posing for pictures, and should therefore be left alone—though in other parts of Australia, conservationists encourage tourists to take wildlife selfies. Rottnest Island off the country's west coast is home to 10,000 quokkas (another photogenic marsupial), and the quokka selfies taken there help raise awareness of their vulnerable status.

[h/t CNN Travel]

Divers Swim With What Could Be the Biggest Great White Shark Ever Filmed

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iStock.com/RamonCarretero

New pictures and video taken by divers show what could possibly be the largest great white shark ever caught on camera, CNN Travel reports.

Deep Blue, a 50-plus-year-old great white first documented 20 years ago, was spotted off the coast of Hawaii recently in a rare close encounter. Divers were filming tiger sharks feeding on a sperm whale carcass south of Oahu when Deep Blue swam up and began scratching herself on their boat. They accompanied the shark in the water for the rest of the day, even getting close enough to touch her at times.


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"She swam away escorted by two rough-toothed dolphins who danced around her over to one of my [...] shark research vessels and proceeded to use it as a scratching post, passing up feeding for another need," Ocean Ramsey, one of the divers, wrote in an Instagram post.


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Deep Blue is roughly 20 feet long and weighs an estimated 2 tons—likely making her one of the largest great whites alive. (The record for biggest great white shark ever is often disputed, with some outlets listing an alleged 37-foot shark recorded in the 1930s as the record-holder.)

Deep Blue looks especially wide in these photos, leading some to suspect she's pregnant. Swimming so close to great whites is always dangerous, especially when they're feeding, but older, pregnant females tend to be more docile.

Though great white sharks are the largest predatory sharks in the ocean, sharks of Deep Blue's size are seldom seen, and they're filmed alive even less often, making this a remarkable occurrence.

[h/t CNN Travel]

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