Whale sharks are known to be nomadic ocean wanderers. But the extent of their travels had not been recorded until a recent study involving the Guy Harvey Research Institute.
Two male whale sharks, named Milo and Lucho by researchers, were tagged in Mexico and tracked over eight months as they completed journeys totalling more than 10,000 miles across the Atlantic before returning to the same spot.
Whale sharks, which can live as long as 130 years and grow to more than 60 feet in length, are the largest and among the most iconic fish in the ocean.
The tracking project was made possible after marine biologist Rafael de la Parra, director of Mexican research organisation Ch’ooj Ajauil AC, swam with the sharks in Isla Mujeres and personally attached fin-mounted satellite SPOT tags in July and August last year.
Information from the tags showed both sharks making long ocean journeys before returning to Isla Mujeres, where they are still swimming nearly 8 months later.
Milo’s journey was the longer of the two, first swimming east, deep into the Atlantic Ocean past Bermuda and returning near the tagging site in February 2019. The track shows he then took a month-long excursion into the Gulf of Mexico, before returning close to the tagging site once again, logging more than 7,000 miles in total.
Lucho had a shorter voyage. He left Isla Mujeres in late August on a 2,713-mile swim through the waters surrounding the Cayman Islands, Cuba, Jamaica, Haiti and the Turks and Caicos Islands before turning around and travelling to the coast of Honduras. From there, he made his way home to the tagging site by Isla Mujeres in late December.
“Tagging these whale sharks on their fins with SPOT tags was a scientific coup,” said Mahmood Shivji, director of the Guy Harvey Research Institute, a collaboration between the Cayman-based naturalist and Florida’s Nova Southeastern University.
“Rafael did an incredible job getting this done. The direct satellite communicating technology of these SPOT tags provide much more accurate tracks of the shark migrations compared to the traditionally used, data archival satellite tags, which have a lot more positional error associated with them.”
More than 150 sharks, including whale sharks, tigers, makos and oceanic whitetips, have been tagged by the research institute in the last decade in order to study their migration patterns.
“Unfortunately, whale sharks are currently on the endangered species list, so revealing their migration behaviour allows us to better understand, conserve, monitor and effectively manage shark populations,” said Greg Jacoski, executive director of the Guy Harvey Ocean Foundation, which is helping fund this research.
Follow the sharks’ journeys in real-time at www.GHRItracking.org.