Little is known about the world’s largest fish, gentle giants that reach 12 meters (40 feet) in length.
Scientists from the Smithsonian Tropical Research Institute (STRI) tracked a female whale shark from the Eastern Pacific to the western Indo-Pacific: 20,142 km (more than 12,000 miles) the longest whale shark migration route ever recorded.
The scientist, Héctor Guzmán, labeled a female whale shark (Rhincodon typus) near Coiba Island in Panama. His team named the shark Anne in honor of the conservationist Anne McEnany, president and CEO of the International Community Foundation (ICF).
The multi-year project also tagged 45 additional sharks in Panama with the sponsorship of Christy Walton’s Candeo Fund at the International Community Foundation, along with STRI and the National Secretariat of Science, Technology and Innovation of Panama (SENACYT).
Guzmán estimated Anne’s position based on the signals from a SPOT tag attached to the shark, received by the Advanced Research and Global Observation Satellite (Argos).
According to Smithsonian scientists, the tag only communicates with the satellite when the shark swims close to the surface. Anne stayed in Panamanian waters for 116 days, then swam to Clipperton Island (France), near Coco Island (Costa Rica) on her way to Darwin Island in Galapagos (Ecuador), a place known for attracting shark groups .
According to the researchers 266 days after they tagged it, the signal disappeared, indicating that Anne was too deep to be tracked and after 235 days of silence, the transmissions began again, south of Hawaii.
After a 9-day stay, she continued through the Marshall Islands until she reached the Mariana Trench, a canyon at the bottom of the ocean near Guam in the Western Pacific where director James Cameron located the deepest point on the surface of the Earth at almost 11,000 meters (36,000 feet) below sea level.
“We have very little information about why they migrate … they may be looking for food, looking for reproduction opportunities or driven by something else,” Guzmán said.
Although the whale shark is the largest fish in the world, there is little information about this species.
According to the biologist Scott Eckert, when he began to investigate these species, his taxonomy was debated and it was not yet clear how they reproduced.
They are found in warm, tropical and subtropical waters, it is believed that about a quarter of whale sharks live mainly in the Atlantic, while about three-quarters live in the Indo-Pacific.
Tourists are attracted to sites where 500 or more whale sharks gather: in Oman, Australia, Galapagos, Mexico, Mozambique, Seychelles. Large groups have also been reported from Taiwan, southern China and the Gujarat coast in India.
Genetic studies show that whale sharks around the world are closely related, indicating that they must travel long distances to mate. Whale sharks have been tracked over shorter distances along similar routes, but this report is the longest recorded migration to date and the first evidence of a possible transpacific route.
Like Anne, other whale sharks seem to follow the northern equatorial current for most of the distance. Large females can swim an average of 67 kilometers (approximately 40 miles) per day.
The whale shark is one of the three sharks that feed by filtration and feeds on plankton, fish eggs, krill, crab larvae, small fish and squid (besides plastic, which they can not digest). As such, they are not considered particularly dangerous and tourism companies that offer the opportunity to swim very close to these sharks are common near the areas where they gather in large numbers. But its size also attracts fishing boats.
They are also wanted for their fins and meat, for their teeth (used in crafts and sold to tourists) and for the cartilage and oil with supposed medicinal values. Juvenile whale sharks often end up as bycatch along with tuna and other fisheries.
This species was classified as endangered in 2016. During the last 75 years, it is estimated that almost half of the world’s whale sharks have disappeared. In many parts of the world, they have legal protection, but regulations are often not enforced.
The fishing, capture and sale of whale sharks is prohibited in Panama through Executive Decree No. 9, signed in 2009 and in 2014, the Environment Authority of Panama approved an additional resolution regulating the whale shark sighting in Coiba National Park and the marine reserve Isla Canales de Afuera. The resolution includes a Whale Shark Observation Manual, but unfortunately tourism activities are not well organized and authorities are not present to enforce the regulations.