Yucatán: Largest Ever Congregation of Whale Sharks

Take a boat off the Yucatán Peninsula this week and you will see the most astounding sight. The water is filled with the gentle giants of the sea, all meeting to feast on little tunny fish eggs. Whale sharks are there in their hundreds, with an estimated 420 of them forming the biggest aggregation. A second group are even further out to sea.


The Mexican Caribbean is home to the whale sharks, which can stray as far north as the Gulf of Mexico and the Southern coast of the USA. While sightings are rare up there, a glimpse of them off the Yucatán can be guaranteed, if you know where to look.

Yet their numbers this year have taken locals and scientists by surprise. Usually they are solitary creatures, meandering their way through the ocean alone or in schools no more numerous than a dozen. The hundreds in the Yucatán Afuera aggregation have brought researchers flocking to record this amazing event.

Flyovers have taken in the scale, with aerial footage and measurements; while scientists in boat are weaving amongst the whale sharks, collecting samples of food in nets.


This is the world's largest fish, with adults reaching lengths of 40 feet (12 meters); yet they are utterly harmless to human beings. Their diet consists mainly of plankton, plants or very small fish. Though, as the recent feeding frenzy shows, mackerel eggs are apparently a favourite.

Meanwhile, over in the second aggregration, in the Yucatán Cabo Catoche, it appears that shrimp and small crustaceans were there main draw on the menu.

Whale sharks swim with their mouths open wide. As water funnels through, they filter out the good stuff and keep it in their stomachs. The rest is channeled out through their gills.


Despite their huge size, whale sharks are not aggressive. They have a reputation for being incredibly docile and moving extremely slowly through the ocean. They will generally ignore human beings, as we aren't food; though well-fed ones are more inclined to be playful. They will happily allow people to swim alongside them and will even give them a 'ride', towing them through the water.

They live up to 100-150 years. Each one has a unique pattern of spots on its back, acting like fingerprints to identify them.


Mike Maslanka, biologist at the USA's Smithsonian Conservation Biology Institute, explained the significance of this find. "With two significant whale shark aggregation areas and, at the very least, one active spawning ground for little tunny, the northeastern Yucatán marine region is a critical habitat that deserves more concerted conservation effort."

His colleague, Lee Weigt, head of the Laboratories of Analytical Biology, added, "Having DNA barcoding is an incredibly valuable resource for this research. It not only allowed us to know what exactly this huge aggregation of whale sharks were feeding on, not readily done from only physical observations of eggs, but it also revealed a previously unknown spawning ground for little tunny."

It is worth noting that whale sharks are considered 'vunerable' by the International Union for Conservation of Nature. This is due largely to over-fishing and trophy hunting. The greatest predator for whale sharks being, of course, humans.

The Oil Leak isn't in the Mexican Caribbean

Since late April, the media has been full of the ecologically tragic events in the Gulf of Mexico. Yet we've not mentioned it in this blog. That's not through any lack of concern (we're watching the unfolding catastrophe with as much horror as everyone else), but because the remit of this blog is really to discuss what's happening in our own backyard. What hadn't occurred to us is that some would be worrying that the beaches of Cancún are currently oil slinks. They're not. The oil is travelling around the Gulf of Mexico; the Mexican Caribbean is, thankfully, free.



For those who have been living under a rock for the past few months, here is the summary of what's going on. On April 20th, 2010, there was an explosion on the Deepwater Horizon oil rig; which located in the Gulf of Mexico, just south-east of Louisana, USA. Several people lost their lives, while an underwater well starting leaking oil into the region. 5,000 - 25,000 barrels worth of oil per day flooded the ocean, with the obvious danger to ecosystems and wildlife. The coastlines of the USA's Louisana, Florida, Mississippi and Texas are all affected, as well as the waters around them.

This is still on-going, with the most pessimistic estimates stating that it will be Christmas before the clean-up is completed. In the intervening months, there have been several attempts to stem the tide of oil still leaking from the pipes. The oil rig's owners, BP, have tried various things, while an army of scientists, engineers and other experts have descended onto the issue. Solutions from the world's commentators have ranged from the feasible to the downright whacky. But most of the media debate has homed in on the more sensationalist stories of - who's to blame? While those in the spotlight seem to spend a lot of time explaining precisely why they aren't to blame.

That's the situation in a nutshell. For us down on the Mexican Caribbean, we can be very thankful for a wonderful natural current that pulls the oil away from us; while being concerned about the future for our marine wildlife.

Try to picture the current of the world's oceans as a gigantic conveyor belt. The prevailing current alongside us has come from West Africa. It surges across the Atlantic Ocean, through the Caribbean Sea and up the Yucatán Straits. Think back to all of those early pirate blogs that I wrote, about how Spanish galleons, reliant on windpower and currents, had to sail north out of the Caribbean Sea, in order to cross into Europe. They were using this very same current.




The Yucatán current

It is this current that has not allowed the oil leak to head south onto the beaches of Cancún and the Riviera Maya.

What is anticipated is that the bulk of the oil, currently trapped in an eddy called Franklin, will be released onto the coastline of Texas, USA. It will then be carried back east and will eventually be taken out into the North Atlantic. There it will continue to do untold damage to the ecosystems of the East Coast of America.

It is possible that, as the eddies break down, oil could just touch the tip of the Yucatán Straits. If this happens at all, it will be in the late autumn, possibly around October or November. This is being monitored, with a series of 80 buoys set up outside of Alacranes Reef a month ago. The buoys are fitted with sampling devices and satellite transmitters, at different depths, which act as an early warning system for those receiving the data. In any case, it is unlikely that oil in the Yucatán would be in liquid form, nor nearly as toxic as it's been in Louisana. It is also likely that it would be well below the surface and far from the beaches, as a south-eastern current will then pick it up and take it into the Florida Straits. While not good, it's certainly not as bad as it could have been.

Yesterday, the internet suddenly erupted with news, from Miami, USA, that the oil leak has travelled down to Cancún. This was news indeed for us, who are eye-witnesses to miles of still unblemished beaches. We are also in daily contact with those on the 'front line', ie the fishermen, boat operators, divers and others who make a living out in the waters of the Mexican Caribbean. None of them have reported seeing any oil or disperants at all. We have been gazing long and hard at the satellite images that purportedly show the oil this far south. While it does, indeed, show a black mark, it doesn't actually say that it's oil. For the moment, we'll believe the evidence of our own eyes and simply report that our beaches are completely free of oil. We'll be the first to tell you when they aren't.



As for the current real effect on the Mexican Caribbean, the concern is for migrating marine life. The larvae of fish and lobsters all travel north. They would have been saved by the eddies and should have made it through; however, the homeward journey could well be another matter.

Also, little is known about the migratory path of the whale sharks. They exist in the Yucatán Straits, but have also been seen near Louisana. Are they the same whales sharks? Or two different colonies? Marine biologists are currently fitting them with tracking devices to find out. If they are the same, then this endangered species is in big trouble; along with the equally endangered bluefin tuna, which spawns in the region of the oil leak. Several agencies are out looking for the whale sharks. Some have been seen already. We are just anxiously awaiting the safe return of the rest.

While the situation further north is terrible, we can confidently state that the oil leak isn't in the Mexican Caribbean. If you have booked, or thinking of booking, your vacation here, then please stop worrying about the oil ruining your break. The Caribbean is still pristine; the sands are still white. We're extremely confident that they'll stay that way.

Sharks in the Mexican Caribbean

One of the most frequently asked questions about the Caribbean Sea is: will something eat me? You can almost see the vision playing out behind people's eyes. There they are, meandering along the white sands in their new, trendy beach outfit. Admiring looks follow them, as they enter the water, sunlight gleaming on their tanned, sea soaked skin. The crystalline Caribbean Sea stretches out for miles of turquoise, each wave sparkling like gems. Beautiful, stunning. And then a shark eats them.

That's one way to ruin a lovely daydream. Let's see if we can get it back on track. The truth is that the above scenario is all very feasible and extremely likely to happen, with the exception of the ending. There are sharks around the Yucatán Peninsula, as evidenced by the fact that the word shark itself is Mayan in origin. But the chances of them eating you range from highly unlikely to extremely improbable. You are far more likely to get hit by lightning than attacked by a shark, let alone eaten by one.

Most shark attacks occur because of mistaken identity. Sharks haven't got good eyesight and therefore may mistake you for a tasty snack. However, the oceans around the Yucatán Peninsula are crystal clear. The shark is more likely to be able to see you very clearly and therefore won't bother you. You are more likely to see a shark by the coral reefs, but even then it will be a rare sighting. No-one has ever died of a shark attack in the Yucatán, though someone did get bitten in 1941.

In April 2008, news spread across the internet about a vicious shark attack in Cancún. While it is true that there was a dead man and there was a shark, the reality wasn't quite as the social panic would have it. The whole story is recounted in more detail over on Annet van de Mortel's blog. The short version is that he got drunk and drowned. The shark was nowhere near him at the time.

The trouble is that everyone has watched 'Jaws' and so sharks are now forever categorised as 'very dangerous to humans' in our mind's eye. In reality, out of 360 known species of shark, only a handful are dangerous. The Great White Shark, the Tiger Shark, the Bull Shark and the Oceanic Whitetip Shark are responsible for the majority of fatal attacks on humans worldwide. By majority, we're talking about 5-15 attacks globally each year, often in self-defense. The other 356 species of shark, for various reasons, are simply not interested in you. Even amongst the dangerous ones, it's rare for them to attack; and divers have been able to swim right alongside without becoming dinner.

So which sharks are swimming in the oceans around Mexico? Loads of them. It's where a lot of those species live. However, you're probably mostly interested in the 'baddies'. Let's look at them:

Great White Shark. This is the species made famous in the 'Jaws' film, however it doesn't visit Mexico. The closest it comes is in the northern Gulf of Mexico, bothering those in the American South. How to avoid being eaten by them: come to Mexico.

Tiger Shark. This one does live here! However, the chances of it attacking are ridiculously unlikely. For a start, they've been hunted close to extinction, with the World Conservation Union (IUCN) having it listed as 'nearly threatened'. While the big game hunters are out getting their trophies, the tiger shark consequently not out there in any great numbers. Even should one turn up, the likelihood of it attacking is very low. Nevertheless, it should be treated with respect. How to avoid being eaten by them: look them straight in the eye, so they know they've been seen and so can't ambush you.



Please note the complete lack of any tiger sharks eating the divers in the above video.

Bull Shark. These sharks do live in the Mexican Caribbean. Again they are the targets of big game hunters and are listed by the World Conservation Union (IUCN) as 'Near Threatened'. However, they've been responsible for only 17 fatalities worldwide, since records began, none of which were in Mexico. How to avoid being eaten by them: punch them in the snout to avoid close contact.

Oceanic Whitetip. This is the shark of shipwreck legend. It lives well off-shore and descends upon sinking ships for its supper. Though it does live in the Mexican Caribbean, it's nowhere near the beach. It's in the really deep waters right out at sea. You are more likely to encounter it on your plate, as this is the shark that commercial fisheries catch for sharkmeat. As a result, it is listed by the World Conservation Union (IUCN) as "vulnerable". How to avoid being eaten by them: punch them in the snout to avoid close contact.

So that's the four biggies taken care of. In the extremely rare situation that you see a predator, then look it in the eye and punch it in the snout, if it gets too close. That's all. But the majority of sharks in the Mexican Caribbean really aren't that interested in you. Your most likely shark sighting will be with a nurse or whale shark, both of whom eat plankton.

Back to the daydream...

... meandering along the white sands in their new, trendy beach outfit. Admiring looks follow them, as they enter the water, sunlight gleaming on their tanned, sea soaked skin. The crystalline Caribbean Sea stretches out for miles of turquoise, each wave sparkling like gems. Beautiful, stunning. So they have a little swim, then get out of the water to lie back on the sun lounger. Their biodegradable sunscreen is reapplied between sips of rum and sangrita; and all the world is great.