Ran Tests on Earth’s Biggest Fish by Marine Biologists – And Unlocked a Startling Radioactive Secret
A team of researchers stands above the body of a whale shark, the largest of all of the ocean’s sharks. They and other team experts have struggled a lot to understand one aspect of this species’ life – but soon, that will all change. In fact, they’ll soon unlock the long-standing anonymity with the help of a radioactive secret passed over the decades.
Although a huge – it can grow to 60 feet in length – the whale shark has its subtleties. The scientists were displeased mostly spending over the years that they couldn’t figure out the tropical sharks’ ages. But that frustration gave researchers a reason to continue studying these docile creatures. How old were they – and how long would they stick around?
In 2020 the researchers finally answered this question, thanks for the preservation remains of two whale sharks kept in Pakistan and Taiwan. And in adopting a new method for dating this unbelievable species, they discovered something else. That is, they saw a strange link between the creatures and a radioactive secret from decades past.
Experts have spent over the years trying to shape out the life spans of all different kinds of sharks. And they’ve really exposed some astonishing statistics. The Greenland shark, for example, can apparently live for almost three whole centuries. Meanwhile, great white sharks dangle around the seas for approximately 100 years.
However, manipulative the same statistics for whale sharks hasn’t been as easy for scientists to confirm. For one thing, whale sharks tend to be a pretty indefinable species to find and study. It’s mainly surprising that they’re so tough to track, considering they’re covered in spots and stripes and can measure in at 60 feet in length.
When the whale shark became an in danger of destruction species in 2016, though, researchers came up with a new method for finding information about them. They outlined tourists to help them – all they had to do was report any whale shark sightings. Then, the pros cataloged all of the data to get an idea of how many of the jumbo fish were out there and where they tended to surface.
The scientists published the results of their study in a 2017 volume of the journal Bio-Science. They recorded approximately 30,000 run-ins with whale sharks, which they endorsed to about 6,000 individual fish. The sightings took place in 54 different countries, with the Maldives, Mozambique, Cancun in Mexico, Western Australia and the Philippines among their favorite hangouts.
But the experts understood that their data hadn’t come from a very different group of whale sharks. Most of the creatures that they or the tourists had marked were young males that measured between 12 and 21 feet long. They couldn’t figure out where the adult whale sharks existence – or how old the age group was.
Finally based on their findings, the scientists could see that the young males didn’t shift around much – but that’s par for the course with whale sharks. Actually, the huge animals try to move so slowly that many of them get hit by ships accidentally. Still, this lack of mobility didn’t make them any easier to research.
At the end of that 2017 study, scientists still knew comparatively a little about the population of whale shark. They didn’t know about the whale sharks activities during the day, where they lived or how they mated. And they couldn’t say definitively how many of them existed – they just estimates ranged from 20,000 to 200,000.
Of course, there are many other species that make easy for scientists to observe and understand them, and this is true for their life and death. But whale sharks don’t stick to customs when they perish, either. When whales die, they float and come to the surface. But whale sharks, on the other hand, go down, leaving experts with little physical verification to study.
Since many years, this left scientists with limited confirmation to help them to conclude whale sharks’ ages. Experts had long relied on cutting into the animals’ spinal column to find rings that could indicate age, similar to those in a tree trunk. They’d count these to estimate the age of a particular whale shark.
On the other hand, scientists finally had to stop using this method due to ongoing arguments about its accurateness. The problem was that they couldn’t work out with confidence how much time each ring represented. With trees, each circle equals a year’s worth of growth, but the same couldn’t be said about the whale sharks’ markings.
The method that would ultimately help them to decide the age of whale sharks came from an unpredictable source. In 2008 a trio of Danish scientists uncovered something that could be helpful in the field of forensics. Physicist Jan Heinemeier led a team who explored a protein located in the eye of humans called lens crystalline.
The nature of lens crystalline stays steady throughout a person’s life, in contrast to various other proteins in the human body. On top of that, they contain carbon and carbon-14, a radioactive isotope that experts can measure and use for dating. That’s because carbon-14 has always been on Earth at varying levels. Scientists, of course, have records of these variations.
When a lens crystalline forms, it comes with a so-called carbon-14 postmark, a level of the isotope that will remain preserved and reveal a person’s age. Heinemeier fairly suggested this dating method would work well for forensics cases. In fact, just after the study was published, he received a request to crack a murder case in Germany with carbon-14 dating.
A year later, Heinemeier fielded another request for help. This time, it came from marine biologist John Fleng Steffensen – an unlikely candidate for forensics help. But Steffensen had a plan, and he thought that Heinemeier could help him. He wanted to know if they could use the same dating method to work out sharks’ ages.
Steffensen’s focus was the Greenland shark, an 18-foot predator that occupied the chilly waters around the country from which it got its name. The Greenland shark has something in common with the whale shark. That is, scientists have struggled to conclude many of the details of their lifestyle, and they had no way to count the animals’ ages, either.
But carbon-14 dating came to their rescue thanks to years’ worth of work from researchers. The group spent half a decade gathering Greenland shark eyeballs from fishermen who had accidentally caught the predatory fish in their nets. With 28 pairs of shark eyes, they finally had enough inherited information to complete their research.
As formerly mentioned, their findings exposed that Greenland sharks can live for hundreds of years. On top of that, their study opened the door for other shark-centric researchers to try the same or a similar method. And that’s exactly what the Australian Institute of Marine Science’s Mark Meekan decided to do.
It was definitely more difficult for Meekan to find genetic samples for his study, even though he was using skeletons and not eyes. Fortunately, he and his team found a pair of whale shark skeletons in two different countries – Pakistan and Taiwan. The former had perished in 2012 and had 15 more expansion rings in its spine than the Taiwanese whale, which fishermen had caught in 2005.
The rings came in handy this time around, too. Meekan and his colleagues used carbon-14 dating to determine once and for all that each ring represented a year of the whale shark’s life. He told National Geographic in 2020, “Basically what we showed is we have a timestamp within the vertebrae. We count the bands from there, and they appear to be annual.”
Meekan added that the ring-counting method established some theories that the experts had held for a long time, too. He told Reuters, “We thought that it was possible that they could reach ages of as much as 100 years. But we weren’t really sure, as we had no confirmed data on age.”
The scientists’ two samples seemed to confirm this long-standing assumption, thanks to the whale shark skeleton from Pakistan. It measured in at about 33 feet in length, and they determined the creature to have been 50 years old. Considering it was only half the size of full-grown whale sharks at a half-century in age, Meekan said they could assume that the creatures likely lived to be around 100.
The researchers dragged carbon-14 from the vertebrae samples, then compared it to carbon samples that had previously been dated. That’s how they identified the whales were 50 and 35 years old – just as the rings showed. So, Carbon-14 dating helped to make clear the ring theory, but it also uncovered a radioactive secret of the seas, as well.
Particularly, from the end of the 1940s onward, several countries around the world tested atomic bombs in the lead up to the Cold War. These practice runs were conducted by the United States, the Soviet Union, France, China and the United Kingdom. In doing so, they released huge amounts of carbon-14 into the atmosphere.
Finally, these atomic bomb tests increased in twice the levels of atmospheric carbon-14. The radioactive material didn’t just float into the air, though. It also soaked into the ocean and got into the food chain. This meant that it ended up inside of animals’ bodies – and in the vertebrae of whale sharks.
Every living human being has carbon-14 in its system, in spite of of whether or not it was around at the time of the Cold War. But those that lived during these tests have “included that spike in Carbon-14 into their hard parts,” Meekan told CNN. He continued, “That means we’ve got a time marker within the vertebrae that means we can work out the periodicity at which those isotopes decompose.”
So, scientists could determine the whale sharks’ ages all thanks to the world’s history in radioactive weapon-making. And knowing how old these creatures live has presented experts with a slew of new considerations concerning their probability of continued existence in the future. This is important, of course, particularly after their categorization as endangered in 2016.
Taylor Chapple is a shark-centric researcher at Oregon State University. Speaking to National Geographic, he elaborated on the importance of carbon-14 dating in his line of work. He said, “This study is actually important because it gets rid of some of those questions about the age and growth patterns of whale sharks.”
Experts need to be familiar with how fast that whale sharks grow – and what their lifespan is – to know how likely they are to fall victim to extinction. In general, species that reproduce quickly will stick around for longer. In the meantime, the slow-to-grow whale shark has seen its population continue to decline over a 75-year span.
Chapple also highlighted the importance of having “real data from real animals.” Meekan’s findings, the Oregon State University researcher said, “[add] an actually critical piece of information to how we internationally administer whale sharks.” For example, the data could move forward experts to devise ways for fishermen to avoid tangling the massive fish in their nets.
This environmentally friendly step would be a mainly important one. Even fishermen who aren’t looking to capture whale sharks in their nets sometimes do so anyway. And such a fault could be massively destructive to the species’ population, which would take too long to recover from so many quick, unnecessary deaths.
Meekan summed it all up when he spoke to the BBC after the study’s publication. He said, “The absolute long life of these animals could be very, very old, probably as much as 100 to 150 years old. This has vast suggestions for the species. It recommends that these things are perhaps strongly susceptible to over-harvesting.”
On top of that, Meekan said that the study had accidentally explained why whale sharks had gone from their common haunts, such as Taiwan and Thailand. The slow-growing creatures couldn’t bounce back from the fishing taking place in those countries. He said, “They are just not built for humans to exploit.”
That report sounds mainly moving next to another ecologically aware worry. That is, the rise of whale shark tourism. In some places, including Oslob, Philippines, shark-watching has raised eyebrows for all the wrong reasons. That’s because participants get too close to the huge fish – or even feed them.
But experts want to find a middle ground. Preferably, one that supports both the undersea species and those who depend on them for an income. Meekan explained to National Geographic, “Ecotourism keeps a lot of people out of poverty in many developing countries around the world, in particular in Southeast Asia.”
Meekan sustained, “We have a responsibility not just to the sharks, but also to those communities to make sure they’ve got a future.” On that note, whale sharks were the ideal creature to help. The fish biologist told the BBC, “Whale sharks are an incredible ambassador for ruin of many people out of poverty.” line life.
And while the study’s result seem to point to a miserable future for the whale shark, Meekan saw it in a different way. He hearkened back to the carbon-14 findings – and the world’s atomic-testing past – in the finish of his interview with the BBC. He said, “This is a good news story – and it shows there is a silver lining to the mushroom cloud after all.”
Certainly, whale shark-related research only continued after Meekan’s team completed their study. In May 2020 researchers exposed that they had tracked a female for 10 months, and that she’d journeyed nearly 10,000 miles in just under two years. Her surprising trek was longer than any other whale shark they had followed in the past.