The Traveler of the Seas
Prior to the recent publication of a study based on data from satellite monitoring, little was known about the world´s largest fish.
By STRI y Javier A. Pinzón
Photos: Shutterstock
In the coastal waters of the Panamanian Pacific roams the whale shark (Rhincodon typus), the world’s largest fish, which grows up to 65 feet in length. Despite its undeniable presence, humans knew little about this fish’s habits until recent satellite monitoring made scientific studies possible.
Despite the fact that the whale shark, the world’s largest fish, spends long periods in the Panamanian seas and finds plenty of food there and in the surrounding waters, it has neither home nor country. The habits of this globetrotter were barely known to humans until last month when the journal Frontiers in Marine Science published the results of a study carried out in Panama that combined technology, large database management, and scientific dedication.
Scientists Héctor Guzmán, from the Smithsonian Tropical Research Institute (STRI), Caroline Collatos, from the Anderson Cabot Center for Ocean Life, and Catalina Gómez, from the University of Panama and the Coiba AIP used a satellite monitoring system to conduct detective-like tracking of 30 sharks.
The final result, which was only recently published in the peer-reviewed journal, describes the routes of the 30 fish as they visited up to nine countries and seventeen marine protected areas. The article highlights one fish in particular that traveled 12.5 thousand miles across the Pacific Ocean.
The Rhincodon typus, like other large sharks, can take years or even decades to reach maturity and reproduce, making it vulnerable, especially when faced with threats from humans. To ensure that measures taken to protect the species will be successful, it was first necessary to understand and predict their behavior.
The first sighting of this giant in Panama was documented in 1932, but aside from being aware of its presence, we knew little about how the species used the coastal waters.
The study published this month began in 2007, with a search for these giants in the Panamanian Pacific in order to tag them with satellite transmitters. The transmitters send a signal to the Argos satellite, which tracks the location of each animal throughout its migrations. An analysis of the results has provided a better picture of the species’s migratory patterns and feeding areas.
Héctor Guzmán emphasizes that once the feeding and breeding areas have been identified, “efforts should focus on the protection of large oceanic areas and establishing marine corridors that extend across national borders; for example, Panama’s Coiba Cordillera Marine Protected Area, or the Eastern Tropical Pacific Marine Corridor (CMAR), which connects Coiba with Cocos Island (Costa Rica), the Galapagos Islands (Ecuador), and Malpelo Island (Colombia).”
Catalina Gómez added, “The study reveals the complexity of protecting whale sharks. The tagged individuals visited 17 marine protected areas in five countries, but more than 77% of their time was spent in unprotected areas.”
Guzmán also stressed the importance of continued periodic satellite monitoring: “First of all, because we still don’t know where the species breeds, so tracking can lead us in the right direction. Secondly, we need continued monitoring because the possible maritime corridors or lanes and marine aggregate areas we’ve identified require careful management and clear protection regulations. Tracking will allow us to better identify those regional routes.” Satellite tracking also revealed a migratory pattern in whale sharks that appears to be associated with circular ocean currents or eddies.
“Eddies are potential feeding areas for migratory oceanic species as they allow species to swim for a long time while feeding,” explained Guzmán. “These eddies, however, are dynamic systems with constant, even seasonal, changes in speed, strength, size, and location. These feeding areas are important to conservation, especially considering their dynamic nature and possible changes due to climate change.”
A. The Tireless Traveler
Anne, a female tagged in Coiba National Park on September 16, 2011, holds the record for distance traveled: she remained in Panama for 166 days, then swam toward Clipperton Island, approaching Cocos Island (Costa Rica) in route to Darwin Island in the Galapagos (Ecuador). Her signal then disappeared, 266 days after being tagged, indicating that the whale was traveling too deep to be tracked. After 235 days of silence, when scientists had given her up for lost, transmissions began again from south of Hawaii. Nine days later she moved on, through the Marshall Islands to the Mariana Trench. By the time her signal disappeared for good, the “gold medalist” had made a 12.5-thousand-mile migration from the eastern Pacific to the Indo-Pacific, the longest migration of a whale shark ever recorded.
B. Northward
Shark No. 54764 was tagged on March 2, 2011, near Canales de Afuera inside Coiba National Park, where the story of its journey through six countries began. Before leaving Panama, the shark stopped off in the Gulf of Chiriquí National Marine Park, then swam on to Costa Rica, where it remained for forty days, Nicaragua (five days), El Salvador (five days), and Guatemala (seven days). On May 4, it arrived in Mexico, off the coast of Chiapas, where it spent 51 days before leaving on June 24 for the deep sea. After 55 days on the open sea, the shark’s signal went missing.
C. To the Open Sea
Shark No. 107719 was tagged on February 18, 2012, in Coiba National Park. After leaving the Coiba Cordillera it logged a long journey to Costa Rica, staying 55 days in the waters off of Isla del Coco National Park, then to the Galapagos Islands, where it spent the next 44 days. After 74 days in international waters, the shark returned to Costa Rica on September 29, 2012 and then to Panama again before its signal was lost.
D. Southward
Shark No. 54749 was tagged on March 3, 2011, also in Coiba National Park. After five days, it moved on to the Gulf of Chiriquí National Marine Park, where the signal disappeared and then returned several months later, on December 6, on the edges of Panama and Colombia´s Exclusive Zone. During its 17-day stay in Colombia the shark visited the Malpelo Fauna and Flora Sanctuary, the Yuruparí-Malpelo National Management District, and the Encanto de los Manglares Management District in the Bajo Baudó municipality, where its signal dropped out.
This research was partially funded by Fundación Mar Viva (Panama), the International Community Foundation (CANDEO), the National Secretariat of Science, Technology, and Innovation of Panama (SENACYT) and its National Research System, and the Smithsonian Tropical Research Institute (STRI).
References:
Hector M. Guzman, Catalina G. Gomez, Alex Hearn and Scott A. Eckert (2018): Longest recorded trans-Pacific migration of a whale shark (Rhincodon typus). Marine Biodiversity Records, 11(1), 1-6.
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