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Open Blue Sharks

Whale Shark Wonder

2017-08-30
Shawn Heinrichs | GHM Spring 2012, Issue 8
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A snorkeler enjoys an encounter of a lifetime with a magnicent whale shark.

Stand on the jetty in Isla Mujeres, Mexico, during a hot July or August morning and you’ll count up to 50 local boats leaving the harbor, each packed with anxious, gawking tourists. Cameras and snorkels in hand, they’ve come for a once rare and sacred big-animal encounter, one that has become predictable and plentiful off the coast of this Caribbean fishing hot spot. An annual gathering of whale sharks—some days the number of animals exceeds 300, all packed into a one-square-kilometer area—is providing the thrill of a lifetime for tourists and an eco-tourism lifeline for local operators. But just a few years ago, the story was quite different.


In January of 2009, I traveled to Isla Mujeres to film schools of sailfish predating on sardine baitballs. Unfortunately, we arrived during a slow period and found ourselves bobbing on the open seas, anxious and frustrated. We passed the hours by sharing stories of our adventures from around the globe. As interesting as these stories were, they paled in comparison to the one Captain Rogelio produced—an unbelievable fish tale about large numbers of whale sharks gathering in these clear, blue waters.


Fins everywhere, the ocean is literally teeming with hundreds of whale sharks.

Having fished these waters for almost three decades, Rogelio is considered one of the most experienced and respected captains in Isla Mujeres. Prior to joining Keen M International as a charter sportfishing boat captain, Rogelio had worked as a commercial longline fisherman who primarily targeted sharks. Over the years, Rogelio had sometimes observed large gatherings of whale sharks feeding on the surface. The whale sharks were of little interest to the fishermen, however, as they were not a commercially targeted species. In fact, the fishermen considered the whale sharks a nuisance, as many a propeller or rudder was damaged from striking a whale shark as it glided just a few feet underwater.


In recent years, Keen M International had begun catering to adventure divers seeking interactions with sailfish. The influx of new customers perked their interest in expanding their eco-tourism offering and suddenly these whale shark gatherings became more than just a curiosity. Rogelio began keeping a logbook of whale shark sightings that he dutifully updated each day.

You can imagine our skepticism as Rogelio described encounters with dozens of whale sharks just floating on the surface, oblivious to his presence. Normally, these animals, some of which can grow to the size of a school bus, are quite skittish. Divers and snorkelers can travel thousands of miles and sometimes work for days to have momentary, fleeting encounters. Seeing the doubt in our eyes, Rogelio produced his logbook and recounted the entries over the past two years. Five, 10, 20, 30 and 50 whale sharks. “Impossible!” I retorted. “In one place, all together, at the same time?”


A beautiful whale shark skims just below the surface, gulping down tiny eggs with its massive mouth.

“Yes, maybe more. Too many to count,” Rogelio replied. If it were not for the fact that Rogelio is a serious man, well-respected, and generally understated, I would have dismissed his claims as a typically tall fisherman’s tale.


But I took him at his word. The opportunity for such a discovery was too great to pass up.


From my prior documentary experience, I knew that whale sharks generally gather in groups for one reason: to feed on plankton or fish spawn. Since these animals were gathering in blue waters, I suspected that spawning activity was drawing them in. Fish spawning tends to coincide with certain moon phases, and armed with Rogelio’s logbook, we targeted the ideal date to search for the whale sharks. I organized an expedition, and early one morning in July, we set out to comb the open ocean in search of the gathering.


When the day came, we set out with a sense of cautious optimism. Scanning the horizon, I eventually noticed a curious disturbance on the surface and we approached for closer inspection. Suddenly, a large fin cut the surface, followed by several more. We drew closer and more fins appeared, stretching to the horizon, as far as the eye could see. In a state of excitement-induced shock, we grabbed our cameras and tumbled into water.


Whale sharks were everywhere with mouths wide open, skimming the surface and gulping down mouthfuls of tiny, clear eggs. The whale sharks converged from all directions, and with no room to maneuver, bowled us over, and continued on their way. There were so many animals in such a small area that they were literally piling up, as one train of sharks collided with another. For the next five days, we spent more than 30 hours in the water filming whale sharks. An aerial survey on the final day counted at least 275 whale sharks in our spot and conservative estimates put the total aggregation at over 400 animals. This was, by far, the largest whale shark gathering ever documented.


Massive gills ush water through them and lter out protein-dense fish eggs.

Economics of Change


Historically, Isla Mujeres has not been a safe place for big marine animals. Especially sharks. No one can better attest to this than Captain Rogelio. In his day, Rogelio was considered one of the best commercial shark fishermen in the business. Now a sportfishing and eco-tour captain, Rogelio was kind enough to share his knowledge of the shark fishery with us. The shark fishery here is well established and has been operating for decades. Each night, up to 20 longline vessels set bottom lines of four-to-five miles in length, each carrying hundreds of baited hooks. Tiger sharks, silky sharks, hammerheads and nurse sharks are frequently caught, but the majority of landings are bull sharks, many of them heavily pregnant females. Back in the day, Rogelio recalled personally landing over 100 bull sharks in just one month. Today, fishermen report dramatic declines in shark catches, yet a shark-processing factory still operates on the island. And driven by escalating fin prices, the fishermen continue to hunt the dwindling populations of sharks.


This dynamic is not unique, and the problem of overfishing in places like Isla Mujeres often seems intractable. Short-term economic gains drive destructive behavior with serious long-term consequences. Economically poor communities need income today to feed their families and choose to ignore the effect their actions will have on tomorrow. The best-intentioned conservation initiatives often fall short because they fail to address this simple reality. But here in Isla Mujeres, an eco-tourism windfall had the potential to fundamentally shift that economic equation.


A massive whale shark appears to be swallowing a tour boat full of excited tourists.

We openly shared our knowledge of the whale shark aggregation, and the island operators soon began working together to locate the whale sharks. The following year, we introduced GPS tracking of the aggregations movement and dramatically reduced the time (and fuel) required for operators to locate the sharks. Word began to spread about the huge numbers of whale sharks and tourists began to pour in from across the globe. The increase in tourists required more boats with captains, crew and guides. These jobs provided more predictable and consistent income than many of the traditional fishing alternatives. As the movement grew, the community even started a festival to celebrate the whale sharks.


This year, a source on the island shared with me that the longline fleet was now operating at five boats or less. Apparently, the owner of the largest fleet has shifted his emphasis to whale shark tourism and is now running five whale shark boats a day. It seems shark conservation has become the happy side effect of a better economic choice for local fishermen, which makes Isla Mujeres a great model for using eco-tourism as a way to promote conservation and help curb overfishing.

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