Latest news with #NeilHammerschlag
Yahoo
20-04-2025
- Science
- Yahoo
Scientists issue warning after observing alarming shift in great white sharks: 'We saw things happen that we'd never expect'
For years, South Africa's Seal Island was a bucket-list destination for marine wildlife lovers hoping to witness the breathtaking power of great white sharks leaping from the ocean in pursuit of seals. But in a troubling turn, the great whites have all but disappeared, as National Geographic detailed — and their absence is sending shockwaves through the entire marine ecosystem. A new study from the Shark Research Foundation, built on over 20 years of data and published in Frontiers in Marine Science, revealed just how much the ecosystem around South Africa's Seal Island has changed since great white sharks began to vanish. The decline started around 2010, but by 2018, the iconic predators had disappeared entirely from the region. "We saw things that we'd never expect," marine ecologist and executive director of the Shark Research Foundation Neil Hammerschlag, a coauthor of the study, said. What followed was a cascade of unexpected shifts, according to the researchers. Without great whites keeping them in check, broadnose sevengill sharks — typically hidden away in nearby kelp forests — surged into the area, sometimes appearing in groups as large as 15. Cape fur seals, once cautious and elusive, began to raft in bold, floating clusters and even chase after cage-diving bait. These changes marked more than just strange new behavior. They signaled a dramatic reshuffling of the food web — one that researchers never expected to witness firsthand. Great white sharks play a crucial role in maintaining ocean balance. As apex predators, they keep populations of other species in check — removing the sick and weak, thereby maintaining healthy food webs. When they disappear, ripple effects follow. With fewer sharks to keep them in check, seals and sevengills increased — but their own prey populations, including anchovies, Cape horse mackerel, and other smaller sharks, plummeted. This domino effect shows what scientists call a "trophic cascade" — when the loss of a top predator causes dramatic changes at every level of the food chain. And while the exact reason for the sharks' disappearance isn't crystal clear, the finger points toward both human and natural threats. Killer whales may be targeting them, but shark nets — which kill up to 30 great whites a year — likely contribute to the decline. Because these sharks reproduce slowly and mature late, even small losses can have major consequences. Experts like Hammerschlag say it's time to rethink how we protect both people and predators. One major change? Ending outdated netting programs and adopting non-lethal beach safety measures, such as shark spotters and electronic deterrents. Do you think America has a plastic waste problem? Definitely Only in some areas Not really I'm not sure Click your choice to see results and speak your mind. On the individual level, supporting shark conservation groups and marine policy reforms is one way to help. You can also check out organizations like the Shark Research Foundation and follow science-backed efforts to reduce harmful fishing practices. As Hammerschlag put it: "We can't stop the orcas. But we can stop the nets." And doing so might just help restore balance to a fragile underwater world. Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.
National Geographic
11-04-2025
- Science
- National Geographic
This was the best place on Earth to see great white sharks—then they vanished
A new study based on two decades of data shows what happens in an ocean ecosystem without great white sharks. Great white sharks, like this one pictured in 2014, were once common residents in the waters around Seal Island in False Bay, South Africa. Photograph by Nature Picture Library, Alamy Stock Photo Built like a torpedo with rows of terrifying 2.5-inch teeth, the world's largest predatory shark is an intimidating sight. So intimidating that some might think an ocean without great white sharks (Carcharodon carcharias) would be a good thing. But their loss causes a ripple effect that transforms the entire ecosystem. A new study in Frontiers in Marine Science shows what happens when sharks vanish. Seal Island, off South Africa's False Bay was once a great white hotspot—one of the few places on Earth where the sharks could be seen surging out of the water to capture prey. 'It was air Jaws,' says marine ecologist Neil Hammerschlag, executive director of the Shark Research Foundation Inc. and a coauthor on the new study. 'I don't think there's anything more remarkable in nature than seeing a 2,000-pound great white flying out of the air with a seal in its mouth.' When the predators disappeared, researchers and conservationists pointed fingers at both encroaching orcas and humans as the culprit. But Hammerschlag and his colleagues, who began studying the ecosystem around the island in 2000 long before the vanishing, saw some surprising changes. The sharks of Seal Island Twenty years ago, Seal Island was 'the greatest place on earth to see great whites,' recalls Hammerschlag, who also serves as president of Atlantic Shark Expeditions. Around 2010, white shark numbers around False Bay started dropping off, and the decline got steeper from 2015 on. By 2018, the great whites were gone. Exactly why the sharks vanished remains a mystery. 'The departure of the white shark is really open to discussion,' says Greg Skomal, a shark biologist with Massachusetts Division of Marine Fisheries who wasn't involved in the study. Some suggest the animals fled because killer whales moved in. Orcas can kill a shark in minutes by precisely carving out its nutrient-rich liver. Hammerschlag thinks humans could also be to blame, as nearby shark nets kill 'somewhere between 25 and 30 great whites a year.' Even a small loss can drive the population into decline, he says, because great whites become sexually mature late in life—males in their 20s and females in their 30s—and have small litters of up to 12 pups. (A baby great white shark led scientists to a huge nursery near NYC.) When the great whites vanished Sharks are thought to keep marine habitats healthy by removing weak and sick animals from the food chain and keeping things in balance. But proving these impacts in a real-world habitat this is challenging. 'These kinds of ecosystem effects are very difficult for us to tease out because they require long-term data sets,' says Skomal. In False Bay, Hammerschlag's and his colleagues partnered with an ecotourism company, allowing them to spend 'full days on the water, 200 days a year.' The team collected over 20 years of data, from before, during and after the great whites' disappearance. 'We saw things happen that we'd never expect,' Hammerschlag says. Broadnose sevengill sharks (Notorynchus cepedianus) suddenly appeared—sometimes as many as 15 in one day. These animals usually hang out several kilometers away in kelp beds, which offer protection from great white attacks. 'From nothing to double digits. It's just mind blowing,' he says. The Cape fur seal (Arctocephalus pusillus pusillus) population also increased. Safe from the threat of sharks, seals were rafting—floating in groups, like a living raft—and going after the cage divers' bait. 'That would have been suicide just a few years earlier,' he says. Both seals and sevengills were on the menu for great whites, so it made sense to see their numbers rise. But Hammerschlag and his colleagues also wanted to find out if the populations of animals that seals and sevengills eat had changed, too. Luckily, scientist Lauren De Vos had installed cameras in 2012 to get a snapshot of fish populations at the time for another study. Hammerschlag's team followed the same method—even down to borrowing the same equipment. As expected, the new data showed a decline in seal prey like anchovies and Cape horse mackerel and sevengill prey, such as smoothhound sharks and pyjama catsharks. This zigzag of impacts—white sharks vanish, their prey increases and, in turn, the animals they eat declines—suggests this isn't caused by problems like pollution or development. 'If habitat destruction was occurring, you would think everything would go down,' rather than some species declining and some increasing, Hammerschlag says. But the study numbers don't reflect that. The small area of False Bay, with relatively few species, made figuring out some of these food chain impacts easier. 'Hammerschlag has that connectivity mapped out because he knows what eats what,' says Skomal. The more species in an ecosystem, the more difficult it is to map the food chain and track the impacts when an animal is lost. Establishing the relationships between animals in a broader area, like the Gulf of Maine, which has hundreds of species, would be much harder, he says. (Cape Cod may have the highest density of great white sharks in the world.) Losing a great white hotspot One possible outcome of all of these shifts is that seals and sevengills might run out of animals to eat. Could the ecosystem collapse? It's too early to know. 'That would be the next question,' says Skomal. 'Is it too many seals?' Today, great whites' incredible aerial displays are a thing of the past at Seal Island. 'You'd never know this was a great white hotspot,' Hammerschlag says. For him, seeing how the whole ecosystem has changed shows the importance of enforcing shark protections and using non-lethal methods to protect beachgoers from shark bites. 'We can't change the orcas' behavior,' he says, 'But we can stop the netting program. That's kind of archaic.'
Yahoo
31-03-2025
- Science
- Yahoo
Orcas Are Terrorizing Sharks, And The Consequences Could Be Profound
A pair of orcas terrorizing white sharks off the coast of South Africa may have captured the popular imagination, but their activities may be quite damaging, new research suggests. Port and Starboard, as the orcas (Orcinus orca) are known, have been documented hunting white sharks (Carcharodon carcharias) off the coast of South Africa for years, handily eviscerating them to feast on their nutritious livers, potentially reducing shark numbers in the area. The impact of a declining shark presence has been difficult to determine, but we may be closer to an answer. Over the last few decades, white sharks have disappeared entirely from False Bay near the Cape of Good Hope – and the cascading effects of the loss of a top predator have been remarkable. "The loss of this iconic apex predator has led to an increase in sightings of Cape fur seals and sevengill sharks, which in turn has coincided with a decline in the species that they rely on for food," says marine ecologist Neil Hammerschlag, formerly of the University of Miami. "These changes align with long established ecological theories that predict the removal of a top predator leads to cascading effects on the marine food web." An ecosystem is a delicate balance maintained by the interaction of the organisms that inhabit it. Although the predators at the top are considered scary by some, removing them from the environment has significant consequences. Suppression of natural predators in Pando forest in Utah, for example, has allowed deer and elk to run riot, feasting on the ancient aspen colony and slowly killing it. For more than 20 years, scientists have been monitoring wildlife populations in False Bay. This meant that they were able to see, in real time, the decline and ultimate disappearance of white sharks from the ecosystem there, and the consequent changes in populations of other species in the food web. From 2000, scientists conducted standardized surveys of white shark sightings at Seal Island, and until around 2015, the shark population was pretty stable. After 2015, however, sightings started to fall dramatically; by 2018, there were no sharks to be seen. The reason for this hasn't been officially confirmed. It's worth noting, however, that white sharks started washing up along the southern coast of South Africa, without their livers, in 2015 – attacks that would later be traced to Port and Starboard. Although the cause of the shark disappearance is yet to be confirmed, we know the effects. White sharks prey on Cape fur seals (Arctocephalus pusillus pusillus). With no sharks around to keep their numbers in check, seal populations boomed. At the same time, sevengill sharks (Notorynchus cepedianus) started appearing – large-bodied sharks that are both prey and competitor to white sharks. As the numbers of Cape fur seals and sevengill sharks rose, populations of the species they prey upon in turn dramatically declined – small fish for the seals, and small sharks for the sevengills. We know, based on other animal population booms, that a sudden increase in food competition between members of the same species can have dire consequences, with individuals taking greater risks to access food, and the weaker individuals starving when they are unable to compete. It may take some time for the ecosystem to recover balance; and, once it does so, it could be very different from the ecosystem it was before. Such changes are pretty normal in the natural world – after all, the world we live in today looks very different from the world of, say, 11,000 years ago, at the end of the last glacial period, or the world 70 million years ago, before the dinosaurs were eradicated. However, understanding what drives such changes in the Anthropocene can help us try to minimize our own impact, and protect vulnerable habitats and the animals that need them to survive. Port and Starboard have been observed hunting white sharks around Gansbaai and Mossel Bay, both further along the southern coast of South Africa. The pair has also been sighted hunting in False Bay, although white sharks are not among the prey observed in that specific area. Nevertheless, it's reasonable to infer that their ongoing mischief at least plays a role in the changes at False Bay. However, we cannot rule out overfishing, pollution, and shark cull programs as contributing factors, either. This is information that is relevant to understanding the wider impact of our own activities. "Future work at this site would benefit from understanding if and how community structure and function may have been altered and the extent to which they will continue to change through time," the researchers write in their paper. "While impacts of apex predator declines are difficult to detect in the wild, especially in marine environments, they are likely more widespread than recognized given the pace and extent of apex predator declines globally." The research has been published in Frontiers in Marine Science. Rock Used as a Doorstop For Decades Found to Be Worth Over $1 Million Antarctic Iceberg Breaks Away to Reveal a Never-Before-Seen Ecosystem Huge Trees Hiding in Plain Sight May Be a Species Totally New to Science
Yahoo
26-03-2025
- Science
- Yahoo
Listen to the first recorded evidence of a rig shark producing sound
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Sharks have a reputation for being silent killers — the top ocean predators are stealthy hunters, but they also lack sound-producing organs found in many other fish. Now, a groundbreaking new study has revealed one shark species may be more vocal than previously thought, making noises comparable to the sound of a balloon popping. For the first time, scientists have recorded evidence of the rig shark — Mustelus lenticulatus — actively producing sound by snapping its teeth, according to research published Tuesday in the journal Royal Society Open Science. 'How sharks maintain social groupings or communicate was thought to be largely body language and possibly through chemical signals; but for the most part has been a mystery,' said Neil Hammerschlag, president of Atlantic Shark Expeditions and executive director of the Shark Research Foundation, a not-for-profit group that aims to increase knowledge and promote conservation of sharks. Hammerschlag was not involved in the research. 'This study opens up a whole new possibility of communication via sound.' The rig shark, a small species that inhabits the coastal waters of New Zealand, typically lives near the seafloor and plays a key role in the region's commercial fishing industry. Unlike most fish that rely on a swim bladder — a gas-filled organ that helps fish maintain their buoyancy and produce and detect sound — sharks lack this feature, making noise production seem unlikely. Lead study author Dr. Carolin Nieder first became curious about sharks' acoustic capabilities after hearing an unexpected clicking sound during behavioral training experiments while earning her doctoral degree at the University of Auckland in 2021. Nieder is now a postdoctoral investigator with the T. Aran Mooney Lab at the Woods Hole Oceanographic Institute in Massachusetts. Although she was unable to investigate the mysterious clicking at the time, it held her interest. Now, Nieder and her team have reported fascinating findings from studying 10 juvenile rig sharks — five males and five females — caught off the coast of New Zealand. The scientists housed the sharks in large marine laboratory tanks, maintained with proper seawater conditions and food, from May 2021 to April 2022. To carefully record any sounds made, the team transferred the sharks to individual tanks equipped with underwater microphones or hydrophones. As the sharks were moved between tanks or gently held, they began making clicking noises, similar to the ones Nieder noticed years ago. Each click was extremely short, lasting an average of 48 milliseconds, which is faster than a human eye blink. Researchers also identified the clicks as broadband, meaning they occurred over a wide range of frequencies from 2.4 to 18.5 kilohertz — some of which can be detected by humans, according to the study. In terms of volume, the clicks were intense, reaching about 156 decibels. The study noted most clicks occurred within the first 10 seconds of handling, becoming less frequent over time. During the initial 10 seconds, the sharks emitted an average of seven clicks, compared with the final 10 seconds with an average of only two clicks. 'As the animals got used to the daily experimental protocol, they then stopped making the clicks altogether, as if they got used to being in captivity and the experimental routine,' Nieder said via email. 'This led us to consider that maybe we are observing a sound making behavior rather than a strange artifact.' The team also observed that around 70% of clicks occurred when the shark was swaying side to side slowly, while about 25% of the clicks happened when the shark was exhibiting explosive movements, waving its head or body around. Only 5% of the movements happened when the shark wasn't obviously moving its body, according to the study. With no specialized sound-producing organs found in these sharks, the researchers are confident that the clicks come from their strong, interlocking teeth snapping together. These platelike teeth, designed to crush prey such as crustaceans, may be responsible for producing the distinctive clicking sound, similar to the sounds some fish make by grinding their teeth. The consistent pattern and frequency of the clicks also suggest the sounds are intentional, rather than accidental, Nieder said. Researchers are still trying to investigate why exactly the rig shark emits these sounds. One possibility is that the clicks serve as a distress signal, which could be a reaction to being handled during the experiment. Most of the clicks fell outside of the hearing range of rig sharks themselves, which extends to about 800 hertz, according to the study. If sharks aren't using their vocal capabilities to communicate with one another, it's possible the clicks could serve as a warning signal or form of aggression around prey or in dangerous situations, the researchers wrote. With more than 500 species of sharks worldwide, it's still unclear whether other sharks share this ability to produce sound. 'I think there is a chance other sharks are making similar noises,' Nieder said. 'This documentation could help (us) start listening to sharks, and maybe we can learn more interesting things about their ecology and lifestyle in their various ecological niches.' Additionally, because the sounds were recorded in a controlled laboratory setting, researchers are eager to discover whether rig sharks also produce these noises in the wild and under what conditions. 'This study opens up the possibility of these smaller sharks 'sounding the alarm,'' Hammerschlag said via email, referencing how smaller sharks scatter in the presence of larger sharks, even if they are out of sight. 'While we really don't know if the sound produced by the rig sharks was simply a byproduct of being handled … it does open up some new questions, possibilities and avenues for future research.'
