In 2023, a team of British marine biologists had an unusual encounter while tracking a bluefin tuna (Thunnus thynnus). They had placed a tracking tag on the tuna to follow its movements at sea, but to their surprise, when they checked the location, they found that the tag wasn’t in the ocean but on a highway, heading for Birmingham in the United Kingdom.
How was this possible? Had someone caught the tuna and taken it, tag and all, to a fish market in the center of England? Had someone stolen the tag and sold it to someone in the country’s second-largest city? Had the fish learned to drive and decided to go to visit the set of Peaky Blinders? None of the above.
Lucy Hawkes, a researcher at the University of Exeter in the UK, led the search for the tag. Hawkes and her team had attached a tracking tag to a bluefin tuna, a species that had disappeared from British shores. It was precisely Hawkes and her colleagues who rediscovered the species in 2021. Since then, they’ve continued to analyze its fate.
The tag adventure began when a team of biologists from the English university attached the device to a bluefin tuna in the harbor of Plymouth.
The first unusual data from the tag indicated that it was on a beach in Whitsand Bay, Cornwall, a 40-minute drive from Plymouth. Researchers assumed the tag had become detached from the tuna and washed up on the beach.
However, when they went to retrieve it, they couldn’t find it. The unsuccessful search for the device, which consisted of a sensor for collecting data and a small orange buoy, left the researchers baffled. The next day, the location system sent a new and disconcerting warning to the team: The tag had started moving and was heading towards Birmingham, a city about 200 miles northeast of Plymouth.
The tag of discord. | Image: University of Exeter
“We assumed someone had picked the tag off the beach and driven home from their holiday,” Hawkes said.
The team decided to change their search strategy and contacted the local BBC radio station in the West Midlands, where Birmingham is located. Almost at the same time, the elusive tag was on the move again, heading north of England, towards the county of Lancashire.
As a result, Hawkes took to the airwaves again, this time to make her appeal to the people of Lancashire via their local BBC station. She explained how they could contact her team in the hope that whoever picked up the tag would be listening.
All This for a Tag?
Why go through so much trouble to find a tag? While it’s true that many of the tags used by marine biologists send the information they collect through satellites, the one used by the British team was different.
“These tags collect very detailed information, but they only transmit their location. To get the rest of the data, we have to recover the tags,” Hawkes said. “They are designed to fall off the tuna after about six days, and obviously, we can’t control where the tuna go, so the tags can be hard to recover.”
These tags transmit location information and compile data from the device’s sensors, including temperature, depth, and detailed information about the fish’s movements and body maneuvers. Hawkes likened these devices to activity wristbands.
Moreover, the tags are valuable not only for the information they contain but also because they cost money.
Despite this, Hawkes said in one of her radio appearances that the likelihood of someone stealing them for sale was low, given that their scientific value far exceeded their market value. “We have deployed 20 to 30 tags over five years and recovered eight so far. The tags are incredibly useful for our work, so I wasn’t ready to give up on this one,” she said.
Hawkes’ persistence finally paid off. After reaching out to local BBC broadcasters for the third time, she received a response. The person who had the tag was a local man named Brian Shuttleworth. Shuttleworth contacted the station after hearing Hawkes’ latest radio appearance. To bring closure to the matter, Hawkes appeared on the radio one last time accompanied by Shuttleworth.
The man explained that he and his wife found the tag while on vacation in the southwest England peninsula. They attempted to contact the phone number on it but were unsuccessful. They planned to try again after returning home, but Hawkes’ radio appearance prompted them to act sooner.
The team of biologists now has the tag in their possession, but we’ll have to wait for the results of their investigations. The acknowledgments section of the future scientific article will likely include the local radio stations and an English tourist who found the tag.
Image | Wikimedia Commons
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