Working Together- Mexico’s bull shark dives

By Cherie Beling

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Author: Mark ‘Crowley’ Russell

a bull shark cruises past a group of waiting scuba divers
A pregnant-looking female with obviously damaged fins swims sedately past a line of eager divers

The bull shark feeding dives of Mexico’s Playa del Carman are an integral part of a programme which combines science, conservation and tourism


Words by , photographs by Valentina Cucchiara

Each year between November and March, hundreds of bull sharks gather in the shallow coastal waters of Cozumel and Playa del Carmen on the Yucatán Peninsula, Mexico. Also arriving is a rapidly growing horde of tourists.

In 1974, when the project to turn the deserted stretch of land that was Cancún into a city of tourism began, the entire state of Quintana Roo was home to fewer than 90,000 people. Today, Cancún itself is home to around 900,000 people; Quintana Roo almost two million, and 21 million tourists passed through the state in 2023.

The accumulation of tourists, and the presence of big sharks, has inevitably led to the rise of shark diving, as it has everywhere in the world where tourists and sharks are present. And, as with other popular shark destinations such as Fiji, the Bahamas, and the northern Great Barrier Reef, shark-feeding dives have become a lucrative industry.

Most of the sharks that appear during the seasonal aggregations are female, and some are clearly large and seemingly pregnant – recently confirmed by a 2023 ultrasound study proving that the sharks didn’t just appear to be very well fed, but were carrying pups.

Chainmail-suited Octavio Valdes of Octavio Bullshark Diving hand feeds a large female

Determining where the sharks go to give birth, and where their young develop – as with any species –is essential for their conservation, however, nobody knows precisely where that is. Bull sharks are viviparous, giving birth to live young in estuarine waters, which, once they have matured sufficiently, head upriver where they are protected from larger, pelagic predators.

As is often the case, the knowledge that much of the Yucatán peninsula is a birthing ground for bull sharks has been passed down through generations of fishermen, while the scientific world is still playing catch-up.

‘Many of the old fishermen describe the coastal lagoons of the region as nursery areas,’ says Dr Nadia Rubio, Director and Founder of Mar Sustentable Ciencia y Conservación. ‘Historically, their presence is known through the accounts of ancient fishermen in important lagoons of the area, such as Nichupté Lagoon, where Cancún is located, which is completely transformed nowadays, and Yalahau Lagoon, which is crossed to reach Isla Holbox, which has also been transformed due to the influx of visitors.’

RIVER OF LIFE

Mangroves play an important role in the life cycle of bull sharks (Photo: Shutterstock)

Bull sharks are euryhaline – meaning they can cope with different levels of salinity; one of only a handful of species able to do so. This ability to transition between fresh, salt and brackish water with ease is thought to have evolved as a survival strategy for juvenile sharks, which spend most of their young lives in fresher water before heading out into the ocean to seek larger prey.

It has also brought them closer to humans than any other species of shark – they have been found swimming in flooded streets and parks in Florida, USA and Queensland, Australia (albeit there have been a number of hoaxes). In 1991, six bull sharks became trapped in a golf-course water hazard just south of Brisbane, Australia, after the River Logan flooded, where they survived – indeed, thrived – for the next 17 years.

A 2022 study proposed Chetumal Bay, at the southern end of the Riviera Maya, as a possible nursery; however, the precise location – even if there is one – has yet to be determined.‘This is one of the hypotheses for our current study, and we are still dealing with the answer,’ said Dr Oscar Sosa-Nishizaki, Principal Investigator at Mexico’s Centro de Investigación Científica y de Educación (CICESE). ‘There are other locations in Cuba and the coast of Central America, so we still cannot be sure where the pregnant females go to give birth.’

Adding to the wider research necessary to ensure the bull shark population remains successful, is the presence of extensive mangrove forests around the coast, an important habitat and shelter for a wide range of species. Although Dr Sosa-Nishizaki points out that it is the type of water that is important rather than the presence of mangroves, the coastal forests play an important role in the development of Quintana Roo’s bull shark pups – and coastal construction has already removed vast tracts of them.

A curious shark with attendant remora passes by the camera for a close inspection

‘Mangroves are vital habitats for bull sharks,’ says Dr Rubio. ‘They provide essential nursery areas, shelter, food resources, and reproductive grounds. Protecting and conserving the mangrove ecosystem is crucial for the long-term health of coastal marine environments.’

Bull sharks are not a protected species in Mexico. That status is given only to great whites, whale sharks and basking sharks, and fishing for non-protected species is still allowed in Mexican waters. Although there is a shark fishing ban in place in Quintana Roo between 1 May and 30 June each year, there is also a continuing problem with illegal fishing operations throughout the region.

A community comprised of Playa del Carmen’s tour operators, fishers, divers and scientists, however, has taken on the task of ensuring that both the sharks and their nursery habitats are protected. ‘Shark dives are controversial, more so feeding ones, but the shark diving industry has proven to be an alternative that ensures [the sharks’] conservation,’ says Cecilia Gutiérrez Navarro, co-founder of the Community Science Program, Proyecto Azul, who has spent the past six years working with both tourists and local communities to raise awareness of sharks and their biological and economic importance.

‘Members of the Playa del Carmen community who provide tourist services related to bull shark diving joined forces to monitor, photo-identify and document the aggregation of this species,’ said Gutiérrez Navarro. ‘They realised that for bull shark diving not just to be a 100 per cent tourist and recreational activity, but achieve real change, service providers, local fishermen and authorities had to be included.’

One of the tagged sharks returning to a feed

In Playa del Carmen, the shark-diving operations take place within the Mexican Caribbean Biosphere Reserve marine protected area, and operators must comply with a raft of legal and safety requirements to obtain a licence to conduct the dives. The dives have helped to benefit the scientific research that will –it is hoped– afford both the animals and their nursery habitats better protection.

The carefully organised dives and close proximity of non-aggressive sharks, for example, gave researchers the opportunity to conduct the ultrasound studies to prove the sharks were pregnant. Rather than having to chase after a fast-moving adult female who might become defensive during the pursuit, the scientists simply had to kneel in the sand and swipe the sharks’ bellies with the scanner as they passed sedately by. Satellite tagging has also been conducted to determine where the sharks disperse to after passing through Quintana Roo.

Shark-diving tourism also enables scientists to collect vast amounts of valuable photographic and videographic data, part of an ongoing project by Gutiérrez Navarro, directed by Dr Sosa-Nishizaki. Supported by the ‘Organized Group of Tourist Service Providers of Tiburón Toro’, divers are encouraged to submit photographs taken during their experiences, more than 10,000 of which have been analysed over the past five years, resulting in the recent publication of the community’s first bull shark photo ID catalogue.

One particularly important discovery that has come from the shark ID project is that there appears to be a great deal of site fidelity exhibited by the bull sharks – they repeatedly return to the same location every year; some of them have been returning to the same location since 2009.

Bull sharks are often considered an aggressive species, but such behaviour is extremely rare during the seasonal aggregation of females

It has been theorised that – rather like green turtles – bull shark females return to the place where they themselves were born, to give birth. This makes the necessity of ensuring the estuaries and coastal mangroves are preserved as important as protecting the sharks themselves, as it would appear that propagation of the species in that region would be impossible without both.

Work is being done at governmental level in Mexico to preserve shark populations. A ‘National Action Plan for the Management and Conservation of Sharks, Rays, and Related Species of Mexico’ is in place, which seeks to address the challenges associated with the fishing and conservation of sharks and rays – and shark tourism is, at this time, providing an important role.

The concept is never going to sit well with everyone, but as Gutiérrez Navarro points out, it boils down to simple economics. ‘It helps the economy in a much more sustainable way than fishing, and the dives bring in more money than fishing,’ she says.

‘Locally, it provides directly for at least 300 families, and even though the bull sharks that arrive in Playa del Carmen are currently not protected by law, the local community of service providers, local fishermen, scientists, authorities, as well as society in general, have come together to work together to consolidate the conservation of these valuable animals.’

OF GODS AND SHARKS

A Mayan tableau depicts Ix K’ab’al Xook (Lady Shark Fin, right) in a bloodletting ceremony (Photo: Wikimedia Commons)

Sharks are a predominant feature in the iconography of the ancient Maya civilisation, which once encompassed the region that is now modern-day Mexico, Belize and Guatamala. Their depiction in Mesoamerican history stretches to the Olmec civilisation, inhabitants of the modern-day Mexican coastal state of Veracruz, whose origins predate the Maya by almost 1,500 years, and whose ‘shark monster’ was a central figure of their religion.

Shark teeth have been found in ancient Mayan sites as jewellery, weapons and even blood-letting tools for human sacrifice. Among them, giant teeth from the extinct Ototdus megalodon, potentially making Maya the people first to excavate and celebrate the world’s largest known shark. Depictions of the Maya Sun God regularly appear to feature a distinctively shaped shark tooth protruding from its upper jaw.

The mighty Usumacinta River – once named for the bull sharks that swam into the Mayan interior (Photo: Shutterstock)

Interestingly, the depictions of sharks are not confined to coastal tribes, where they might be expected, but have been found at sites so far inland that their inhabitants would have had little knowledge of what an oceanic animal would look like.

Xok and Xook, the Mayan words for ‘shark’, were regularly adopted by Mayan rulers, such as King Ha’ K’in Xook (Water Sun Shark), who ruled between 767-781 in what is the modern-day Guatemalan city of Piedras Negras; and Queen consort Ix K’ab’al Xook (Lady Shark Fin), who ruled the kingdom of Yaxchilán between 681-730, and is depicted on the right-hand hand side of the tableau above, about to participate in a blood-letting ceremony conducted by a priest wielding a noticeably shark-toothed-shaped blade.

Both of these ancient cities were some 300km from the coast, but both lie on the Usumacinta River, once called Xocolha, in turn possibly derived from ‘Xok Ha’ – or ‘Shark River’. As the only species of shark capable of swimming so far upriver – with the exception of true freshwater sharks, found only in Asia and Australia – some scholars have suggested that it is very specifically the bull shark that is the basis for the Maya’s depiction of sharks.

Beyond the dispassionate realms of science, however, many people involved with shark conservation look to the sensibilities of a time before mass tourism, perhaps with a nod to the ancient Maya civilisation (see box above), when humans and bull sharks were intricately linked.

‘I believe that fostering a deeper connection and empathy with the places we visit and the local communities, can significantly enhance our travel experiences,’ says Dr Nadia Rubio. ‘Sharks hold a significant cultural and historical importance in our region, dating back to pre-Columbian times – they were revered and integrated into the culture of ancient civilisations such as the Maya.

‘By delving into the rich cultural heritage surrounding sharks, travellers can gain a deeper appreciation for the places they visit and the communities they encounter. This not only enriches our travel experiences but also fosters a greater sense of respect and understanding towards the environment and its inhabitants.’

Much as we might yearn for it, there is no return to that distant past. Humanity and mass tourism are here to stay, and so bull shark feeding dives have become a controversial but perhaps necessary piece of an intricate tapestry being woven by local communities, scientists, divers and conservation groups to ensure their populations remain protected.


Valentina was diving with Octavio Bullshark Diving in Playa del Carmen. For more information about Mar Sustentable Ciencia y Conservación visit www.marsustentable.org and for about the work of Proyecto Azul and shark protection, visit www.baalche.com/pages/projecto-azul

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