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(CNN) - It was an aquatic case of synchronicity.
Almost three years after a female pilgrim shark was tagged with a satellite transmitter in Malin Head, the northernmost point of Ireland, it was photographed in Nauset Beach, Massachusetts.
The event marks the second recorded observation of the transatlantic movement of the species, according to a study by Queen's University Belfast and Western University in Ontario, published in the Journal of Fish Biology in October.
Apparently, this may not seem like a notable event, but the amount of unlikely events that lined up perfectly to make identification of this shark possible would make even the most skeptical wonder if it was an intercession of fate.
And even more fortuitous is the fact that this observation provides a window to the movement of one of the weirdest looking fish in the ocean, which has a huge and fluted structure in its mouth where one might expect soft meat.
A three year story
The series of lucky events began in August 2014, when the shark was tagged with a satellite transmitter right next to Malin Head, an important point of pilgrim sharks in the northeastern Atlantic. After a few months, the device stopped transmitting data.
"That is not unusual," said Jonathan Houghton, one of the study's principal investigators at Queen's University Belfast. "If you put electronic products in the sea, some things just fail after a while."
But then, out of nowhere, in June 2017, the shark was photographed by an underwater photographer more than 4,600 kilometers away, off the east coast of North America.
The photograph moved through Europe, and when it reached the research teams, they noticed something surprising: connected to the tracking device that the shark was no longer working there was a small and unmistakable device that the researchers had designed as a buoyancy aid. At that time, this shark was the only one wearing the modified device. They realized that this was the same shark they had labeled almost three years before.
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This marked the second time it was observed that this species was moving across the Atlantic, the first was in 2008.
“Until that time, we had never been able to follow the movement of a shark for more than, say, nine months or a year. So understanding their movements on a three-year time scale, on a different side of the Atlantic, that completely changed our thinking, ”said Houghton.
And it would not have been possible without a stroke of luck. “Scientists love to say that everything we do is based on an absolutely brilliant pre-thought. But sometimes, we are lucky, ”he admitted.
Shark of interest
The basking shark has long been a kind of interest. The public has shown interest due to its unusual appearance (to put it mildly). Scientists are more interested in decreasing their population in the Pacific.
"In the mid-twentieth century there was a lot of conflict between pilgrim sharks and commercial fishing," said Paul Mensink, who conducted the research at Western.
Measuring up to 12 meters long, it is the second largest fish and has a habit of bumping into boats and becoming entangled in fishing equipment. This led to a specific effort to eradicate sharks in the Pacific. "There is a bit of dark history on the Pacific coast," said Mensink.
In the Atlantic, however, the species is healthier. Here, sharks have two populations, one in the Northeast Atlantic, near Ireland and Scotland, and the other in the oceanic region of North America.
In the North-East Atlantic and North Pacific oceans, the species is considered endangered, while the International Union for the Conservation of Nature considers it "vulnerable."
The shark's journey from the northeastern Atlantic to the waters of North America represents a mixture of these two populations. "We knew that the transatlantic movement could happen, but it wasn't very common," Houghton said.
What they did not know before this study, however, was whether sharks that ventured across the Atlantic tended to return to their native populations. "That this animal, three years later, seems to have become part of the American population is a very new finding," said Houghton. "There is no kind of elastic cord effect in which they have to return to the other side."
When you think about it like this, Mensink said, "the oceans get a little smaller somehow."
What is in your mouth?
Probably not only Houghton and Mensink turned twice when they saw the photo. Most of the people who ran into him probably felt tempted to look. For the inexperienced eye, the inside of the pilgrim shark's mouth seems to contain a ribcage.
That, of course, is not what it is, since sharks are cartilaginous fish that lack bones, Houghton explained. Actually, it is a tough and structured cartilage that is only visible when the shark's mouth is open.
The structure may not be a ribcage, but it serves some of the same purposes. “When the shark opens its mouth, it's like opening the jacket on a windy day. It inflates and the cartilage gives it some structure so that your skin does not agitate, ”said Houghton.
It also has the least practical purpose of making the basking shark one of the strangest fish in the ocean.
Shark
