The Adventures of Coco: the whale shark being monitored by Galapagos scientists
by Michelle Carrere
12 October 2020
For the first time, scientists have managed to track a Galapagos whale shark by satellite entering the Isla Coco National Park in Costa Rica. The finding is an important test to protect the migratory corridor that connects these two marine protected areas and that use numerous endangered species.
Coco was tagged in August. It was the scientists’ first field trip after confinement by the pandemic. The brand was a satellite device that was firmly installed on its dorsal fin. It was put on with a “pressure clamp”, a minimally invasive method, and Coco barely felt it. She continued swimming carelessly, indifferent to the presence of the frogmen who, next to their 12 meters long, seemed tiny.
Coco is female and was born as a shark, but since she is so large and eats plankton – unlike most sharks known to be carnivores – science decided to call her, and all of her species, a whale shark (Rhincodon typus).
Scientist Alex Hearn stared in amazement at the computer screen where he could read Coco’s exact position in the ocean, just three weeks after it had been marked on Darwin, the most remote of the islands in the Galapagos archipelago.
Thanks to the device installed on its dorsal fin, it is possible to follow its path, since each time it comes to the surface it sends a signal into space that is captured by an orbiting satellite.
The whale shark is the largest fish in the world. Photo: Jonathan Green
The route indicated by the satellite mark was clear. Coco had begun to move quickly and without distraction through the Coco mountain range. A chain of mountains and underwater volcanoes that stretch for 1200 kilometers from the Galapagos Islands to the Pacific coast of Costa Rica. After three weeks of travel, the huge animal entered the Isla Cocos National Park, in Costa Rica. It was the first time that the scientist had seen a Galapagos whale shark enter this protected area and Coco was named after the discovery.
For 10 years, Hearn, who is part of the Whale Shark project of the Galapagos Science Center of the University of San Francisco de Quito, has installed tags on these animals to know what their migratory patterns are. It was not the first time that a whale shark followed the route of the Cordillera del Coco, but always, somewhere along the way, it deviated before entering the Costa Rican National Park.
This trip was different and provided irrefutable proof that whale sharks move between both marine reserves, Galapagos and Isla Cocos, through this MigraVía that scientists have insisted on protecting for years to protect the species that transit there, such as sharks and turtles in danger of extinction.
Coco stayed only two days in the National Park of Costa Rica and then continued to the coast of mainland Ecuador. The last time the GPS sent a signal was two weeks ago and it was halfway there.
The mysterious Coco
Coco is probably in her 50s, but like a reserved lady, no one really knows her age. And it is that human beings have not been able to discover exactly how long it takes to grow this fish, the largest in the world. It is believed that they do it quite quickly in their first years of life and that then that curve flattens out, says Hearn.
When Coco was born, she was probably between 70 and 90 centimeters tall, but could grow to 20 meters and live up to 100 years.
Known for being solitary animals that swim in open water, there are few places on the planet where they are seen together. In most of these cases, they are juvenile individuals, that is, they have not reached their reproductive size and do not exceed seven meters. In addition, they are generally male and are found to feed. This is the case, for example, of whale sharks that can be seen off the coast of Peru.
The Galapagos whale shark population is unique in that nowhere else in the world are there so many adult females. Photo: Jonathan Green
But Coco is part of a different and unique population in the world, that of Darwin Island, in Galapagos, where up to 99% of these animals are adult and large females. “They are twice the size of what you see in the coastal aggregations,” says Hearn.
They arrive there every year between July and October, but they don’t stay. They are passing through and for now nobody knows why, because they are not seen feeding. It is not known where they go next, because they all take different directions. Similarly, it is not known why Coco went to Isla Cocos, or why she is now going to the coast of Ecuador.
Perhaps to reproduce, but the truth is that about 20 newborn whale sharks have been found globally and generally in deep waters. That is why it is believed that these animals do not have a precise breeding area. You also have no idea where they copulate with males.
In short, everything is a mystery. Why are they only female? Why are there only adults? Why aren’t they feeding? Where are they going?
Science still has many mysteries to be solved around the whale shark. Photo: Jonathan Green
For now, scientists are concentrating on trying to answer the last question. Something not easy because “each shark we tag goes to a different place,” says biologist Sofía Green, a researcher and member of the Whale Shark team. Knowing where they are going “is one of the biggest mysteries that we are trying to solve.”
Also discovering what they do in each place would imply another type of investigation. “I would have to go, look for them, perhaps with a plane, perhaps in boats with drones and observe their behavior,” says Hearn, but the budget is limited and it is necessary to distribute the efforts well since, in addition, scientists are interested in studying another place where these animals are added to the south of Galapagos. According to Hearn, it could be a feeding area “because it is an area where, in fact, the fishing fleet is concentrated,” says the scientist.
Protect the MigraVía
The information provided by Coco is an important piece of evidence that adds to the list of arguments that scientists have to protect the Migration Route that links the Galapagos Marine Reserve and the Isla Coco National Park.
A study carried out by the NGO MigraMar and the Pontificia Universidad Católica del Ecuador on the biological justification for the creation of the MigraVía, indicates that despite the conservation efforts in each marine protected area (MPA), “a marked decline has been detected population of highly migratory species, such as sharks and sea turtles that move between said MPAs and the territorial seas of the region ”.
Coco is the first Galapagos whale shark to enter the Isla Coco National Park in Costa Rica. Photo: Jonathan Green
He also assures that “it has been accepted that overfishing is the main cause of the population detriment of many migratory marine species”, including sharks, rays, turtles, dolphins and seabirds that “are caught as associated or incidental fishing of industrial fishing fleets and semi-industrial ”.
Therefore, the scientists postulate that the next logical step to strengthen the marine conservation efforts of the governments of Costa Rica and Ecuador is the protection of the corridor that Coco traveled and that have also used at least 389 animals of 15 different species, such as sharks. hammerhead (Sphyrna lewini), silky sharks (Carcharhinus falciformis), thresher sharks (Alopias pelagicus) or green turtles (Chelonia mydas), leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata), all on the Union’s Red List of Threatened Species International for the Conservation of Nature.
Proposed area to protect the migratory corridor between Galapagos and Isla Coco. Map: Biological justification study for the creation of the MigraVía Coco Galapagos by MigraMar and Pontificia Universidad Católica del Ecuador.
The proposed area has an approximate area of 240,000 km2 that extends between Ecuadorian and Costa Rican waters. “The project has already been presented to both countries and has been welcomed by the directive of the Marine Corridor (of the Eastern Tropical Pacific),” says Hearn, alluding to the regional conservation initiative that seeks to create joint measures between Colombia, Ecuador, Panama and Costa Rica for the ecosystem management of the marine protected areas of Galapagos, Coco, Malpelo, Gorgona and Coiba.
Although the COVID-19 pandemic somewhat delayed the original schedule, “now they are putting together the roadmap to see what the steps would be to move this forward,” adds the scientist.
The protection of the migratory corridor that connects Galapagos and Isla Coco is important to protect the species that move between both marine protected areas. Photo: Jonathan Green
So far, science has not found anywhere else on the planet that is home to a population of whale sharks like the one found in the Galapagos. Only in two other parts of the world are adult females like those in the archipelago frequently seen – in Saudi Arabia and St. Helena Island in the Atlantic – Green says.
However, the biologist points out that these populations do not have the number of mature female individuals as the Galapagos population does, so this marine sanctuary continues to be the most exceptional place in the world for the conservation of this species considered Endangered by the International Union for Conservation of Nature (IUCN) and about which so little is known.
Main Image: EFE File Resource / Capture Video
This report is published in EFEverde by courtesy of Mongabay Latam
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