Dive Site: Isla Mujeres, Mexico

To truly appreciate this magnificent animal, there’s no better place than Isla Mujeres, where you can confirm their value not just once, but several hundred times over.

There are whale shark hotspots from Mozambique to the Maldives, from Honduras to Djibouti. But there’s only one place that can call itself home to the largest aggregation of whale sharks on the planet: Isla Mujeres, a small island off the northeastern tip of Mexico’s Yucatan Peninsula. Every year from May throughout most of September, the deep waters approximately 20 miles from the island attract these ocean behemoths by the hundreds. In 2009, aerial research teams counted a record 420 sharks on a single flight, making the Isla Mujeres aggregation the largest in the world by a large margin. Although local fishing communities have known about this phenomenon for decades, it only earned international recognition very recently. The first scientific surveys of the Isla Mujeres whale sharks began in 2002, and only in the past six or seven years has the island become established as the No. 1 destination in terms of whale-shark tourism. The sharks are attracted to the region each year by the annual spawning of the little tunny, congregating to gorge upon the egg slick that coats the sea’s surface during the summer months. Unlike in some other locations where whale sharks are controversially fed to create a tourist attraction, Isla Mujeres visitors can rest assured that they’re experiencing the sharks in their natural environment, exactly as they should be. 

There are other whale shark aggregations off the Yucatan Peninsula too, at Cabo Catoche, for example, where smaller numbers come close inshore to feed on zooplankton blooms. However, scientists believe that the exceptional scale of the Isla Mujeres aggregation is due to the easy availability of food in the island’s waters during the tunny spawning. Whale sharks must eat a huge amount to sustain their enormous size. According to studies conducted by researchers in the Yucatan, the density of the tunny eggs at the Isla Mujeres spawning ground means that the whale sharks can consume 2.5 times the amount of energy in a given period of time there than they could in the same period of time elsewhere. This theory is supported by the fact that the tunny spawning attracts several other opportunistic pelagic species, including manta rays, sailfish and great schools of golden eagle rays. This summer glut of food has consequently turned the waters around Isla Mujeres into a true diver’s paradise. The deep water where the spawning takes place is untainted by rainwater runoff, and is consequently crystal clear, as well as consistently warm. As a result, there are no real limitations on the amount of time one can spend with the whale sharks, either in terms of comfort, or in terms of air consumption and no-decompression limits, thanks to the fact that all encounters are conducted on snorkel. 

Scuba is prohibited within the Whale Shark Biosphere Reserve, an area that includes Isla Mujeres, and which was established in 2009 to protect the island’s whale shark population. It is thought that divers and their bubbles have the potential to disrupt the whale sharks; and in fact, there’s no need for cylinders due to the animals’ tendency to stay on the surface to feed. Whale-shark encounters at Isla Mujeres are controlled by several other regulations, too, all of which are intended to preserve this phenomenon and ensure that it continues into the future. These include a strict season, outside of which it is illegal for tour boats to operate; rules that prohibit snorkelers from touching the whale sharks or approaching within 6.5 feet (2m) of them; limitations to the number of snorkelers in a group, all of which must be led by a licensed guide; and a prohibition on flash photography. Rules like these make Isla Mujeres the best choice for conscientious whale shark addicts, creating a destination where you can see these gentle giants in a way that is both low-impact and hugely rewarding. There’s a reason that whale sharks feature highly on the bucket list of so many divers, with their beautifully spotted skin, docile nature and gargantuan size, they are truly impressive animals to behold. Few divers can forget the sight of an oncoming whale shark, its cavernous mouth gaping wide as it trawls the sea’s surface for food, or the sense of sheer awe that comes from finding oneself side-by-side with the largest fish in the ocean. To encounter even a single whale shark is a lifetime highlight for most divers, and yet Isla Mujeres offers the unique opportunity to see as many as 50 sharks on a single snorkel trip. 

Despite measuring up to 40 feet (12m) in length, whale sharks pose no threat to humans. Their diet consists solely of microscopic food like fish eggs and plankton. The sharks are placid, unconcerned with anything much other than consuming the vast quantities of food they need to survive. Unfortunately, whale shark numbers around the world are in decline as a result of overfishing, to the extent that the species is now classified on the IUCN Red List as Vulnerable. Whale shark hotspots like Isla Mujeres have the potential, if properly managed, to highlight the tourism value of these exceptional animals, making them worth conserving as financial resources in those countries where they are prevalent. The whale shark’s economic worth is just a bargaining chip for its survival, however; the sharks’ presence in the ecosystem is valuable in its own right. To truly appreciate this magnificent animal, there’s no better place than Isla Mujeres, where you can confirm their value not just once, but several hundred times over.

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