Impacts of
Tourism on Sharks and Rays

< Human Threats To Sharks & Rays

Shark and ray encounters are one of the fastest-growing sectors in the wildlife tourism industry. Over one million people join tours annually to dive or snorkel with sharks and rays in their natural habitat (hereafter referred to as shark tourism). Shark tourism occurs in more than 40 countries, focused on around 50 shark and ray species, including many of those listed on the Convention on the Conservation of Migratory Species of Wild Animals (CMS).

Many migratory sharks are increasingly rare, due to overfishing and other human pressures, and are naturally cautious around the unfamiliar setting of divers and boats. To ensure reliable viewing, operators will feed or otherwise attract sharks to the boat or dive site, or alternatively may take the tourists to swim or dive with sharks at feeding areas, cleaning stations, or other places that they visit regularly.  

When conducted responsibly, shark tourism can provide a range of benefits, from economic development to increased legal protections for threatened species and their habitats. However, the rapid expansion of this industry can also lead to disruption of shark behaviors, increased injuries to the focal species, and degraded habitat. In this fact sheet, we explore the potential for negative impacts from shark tourism, particularly on CMS-listed species, and how they can be mitigated or avoided.

Attracting and Feeding Sharks

Most sharks and rays are seldom seen in the wild. To encourage them to stay visible to divers, it is common for operators to use bait or other attractants to attract and aggregate sharks. Tactics can range from hand-feeding Whale Sharks (Rhincodon typus) to using dive torches to excite zooplankton, which are then preyed upon by Reef Manta Rays (Mobula alfredi), or even playing heavy metal music through underwater speakers to attract White Sharks (Carcharodon carcharias). Two well-studied examples are cage diving with White Sharks, likely the most regulated subset of shark tourism, and feeding Whale Sharks, which has minimal management in place.

White Sharks are large apex predators and, as such, they are potentially dangerous to people. To create a safe tourism experience, a protective cage is deployed to allow divers or snorkelers to observe the sharks from underwater. White Shark cage diving began in the 1970s in South Australia and has subsequently been developed in the USA, South Africa, Mexico, and New Zealand. Tourism focuses on areas where the sharks are naturally found in relatively high densities, particularly near seal colonies which are important prey for White Sharks. To bring the sharks close enough for underwater viewing, operators typically use some combination of scent (generally small pieces of fish) and baits, seal-shaped decoys, or sound-based attractants, depending on local regulations and operator preferences.

Earlier in the industry’s development, some operators would drag baits over the cage to encourage the sharks to closely approach the tourists. This led to minor injuries to the sharks if they inadvertently struck the cage or, worse, become entangled in grating or lines. Managers and operators have consistently tightened legal and informal regulations to avoid such practices over time.

There has always been a high level of public and management interest in the effects of tourism activities on White Shark behavior and biology. This is partly due to their threatened status, as a globally Vulnerable species on the IUCN Red List of Threatened Species, but largely because vocal concerns have been raised about the potential for sharks to associate watergoers with food in other situations. To minimize the possibility of habituation, operators are not allowed to feed the sharks; instead, baits are removed from the water as sharks approach. White Sharks are accomplished ambush hunters, and sharks do sometimes manage to consume the baits, so the amount of bait that can be used in a day or trip is also regulated to incentivize operator attentiveness. 

Tagging studies have demonstrated that White Sharks do increase their activity level while around tourism vessels, expending additional energy. However, as there is little or no food reward, more resident sharks appear to become increasingly disinterested and less inclined to approach tourist boats over time. However, such behaviors are variable, with other individuals continuing to approach boats. Biochemical studies have found no overall change in diet or decline in body condition in the White Sharks sampled from tourism vessels. There may be some effect on the sharks' social dynamics, with larger sharks showing dominance behaviors and possibly increased aggression in the face of perceived competition from other White Sharks, but clear patterns have not been documented.

Cessation of tourism activities at the Neptune Islands in South Australia, as part of the health response to the COVID-19 pandemic, led to a 51-day break in White Shark tourism activities, the longest gap in 12 years. Long-term passive tracking of tagged White Sharks through this period allowed for an opportunistic analysis of changes to shark residency and movements. The absence of tourism vessels had no effect on White Shark activity or residency, indicating that the presence or absence of tourism makes little difference to the sharks.

The filter-feeding Whale Shark, in contrast, is harmless to people. Snorkeling and diving with the species has become a highly popular tourism experience in the few locations they predictably aggregate. While Whale Sharks are often thought of as strict planktivores, they will also target small fishes, and fishers at a few sites in Indonesia and the Philippines began feeding Whale Sharks that were attracted to their fishing activities. This has developed into a major industry over the past decade, with the best-known and most accessible site at Oslob, on the island of Cebu in the Philippines.  

Oslob has become one of the most popular tourist destinations in the country, attracting hundreds of thousands of people each year to view the sharks and creating significant economic benefits for the community. The Whale Sharks are hand-fed in a small viewing area close to shore that is demarcated with buoys. Operators paddle most tourists out to the sharks in small outrigger canoes, where the sharks are individually fed from other canoes. Tourists can either view the sharks from the boat, snorkel, or dive with the sharks.

While Oslob is a natural seasonal migratory corridor for Whale Sharks, a small number of sharks have become highly habituated to being fed, appearing daily over months to years. Studies on 208 individual sharks over three years of monitoring found a diversity of residence patterns, with 21 seasonally resident and nine year-round resident sharks, suggesting some degree of dependency in the latter group. As sharks become more resident, they become highly tolerant of boats, which increases their risk of propeller injuries; lacerations were present on 28% of the sharks, with overall scarring rates much higher than at other Whale Shark tourism destinations. Sharks accumulated injuries and abrasion damage (due to regularly bumping boats while feeding) during residency periods. As the feeding activities take place in warm shallow water, the sharks often dive into deeper water off the site to cool down after feeding ceases for the day. Tagging studies estimate a 7% higher metabolic rate for sharks that frequent the area due to the time spent in warm water and constant suction-feeding the sharks employ. The long-term effects of higher injury rates and daily energy use remain unknown at this point. 

Aside from the clear designation of the interaction zone, there is little regulation of tourism activities at the site. While in-water encounter guidelines exist, enforcement is low, with 93% of tourists breaching the directives by approaching within 2 m of the sharks, often touching them. Tourist surveys found that 96% of them felt crowded by boats in the viewing area, while a carrying capacity study concluded that Oslob is “overcapacity”, in terms of swimmers, and “greatly overcapacity” in the number of boats present.

The risk posed by shark tourism activities will largely be dictated by the ecology of the species in question. Many migratory sharks and rays are wide-ranging; using bait as an attractant for Blue Sharks (Prionace glauca) or Shortfin Makos (Isurus oxyrinchus), which often swim hundreds of kilometers a week, is unlikely to result in habituation or dependency. More resident species, however, can quickly become accustomed to regular feeding. Some long-running shark-feeding sites, such as the well-researched seasonal aggregation of Bull Sharks (Carcharhinus leucas) at Shark Reef in Fiji, have demonstrably had negligible long-term effects on shark behavior and diet. Newer sites, with minimal legal or self-regulation in place, can be prone to 'overfeeding', which has a higher chance of creating dependency, associated negative health outcomes, and behavioral changes in the animals. The same is true for discards from fishing activities, which introduce large quantities of shark food into specific sites on a regular basis. While such activities are unlikely to negatively affect the overall conservation status of the focal species, it is important to safeguard the welfare of local shark and ray populations. Where food is being provided, it should be high-quality, part of the animal's natural diet, and distributed at a minimal level.

Pressure on Key Habitats

Most shark tourism is based on visiting sites where sharks can be reliably seen in the absence of attractants. This tourism can vary from shore-based snorkeling to multi-day expedition-style dive trips to see pelagic sharks at remote volcanic islands and seamounts. In general, these activities are regarded as low-impact on sharks and rays, but the regular appearance by people in important shark and ray habitats, such as feeding areas, cleaning stations, or reproduction sites, creates the risk of disturbing the animals or disrupting important natural behaviors. Where there is a near-constant human presence, there is a threat of chronic stress and disruption. Proactive management is needed to avoid negative effects.  

Monad Shoal, a large seamount off the island of Malapascua in the Philippines, is one of the only sites where Pelagic Thresher Sharks (Alopias pelagicus) are routinely seen by divers. Monad Shoal acts as a health and hygiene stop for the sharks, where small wrasse inhabit 'stations' on certain reef structures. Sharks accumulate external parasites over time, which can cause chronic disease, developmental problems, and respiratory issues if they attach to the gills. Normal wear and tear from the sharks’ active predatory lives also result in minor injuries and dead skin, which can lead to infection. The wrasse eat parasites and dead tissue, providing a useful service to the sharks – while gaining an easy meal themselves. The sharks visit the stations regularly, with at least some sharks present almost every day, creating a popular attraction for shark tourists. 

The cleaning stations themselves are not immediately obvious, as they are simply patches of reef inhabited by small wrasses. This makes them vulnerable to physical damage from inexperienced divers, by accidentally breaking off coral or resting on the stations. Close approaches by divers also disturb the sharks, which circle slowly around the stations to allow the wrasse to stay with them. The first cleaning stations to be found, at ~15 m depth on the top of Monad Shoal, were physically damaged by divers and the cleaner fish abandoned the sites. Deeper cleaning stations on the edge of the Shoal have now had heavy blocks put in place around them, with ropes linking the blocks to fence off the cleaning areas while also providing a convenient hand-hold for divers to use while viewing the sharks. Now, divers can watch the sharks clean from an appropriate distance, while the Thresher Sharks and cleaner fish maintain unhindered access to the site.

Darwin and Wolf islands, in the far north of the Galapagos archipelago in the Eastern Pacific, share a large migratory population of Scalloped Hammerhead Sharks (Sphyrna lewini). During the day, sharks school on the upstream side of both these small volcanic islands, where they rest in the water flow, attend cleaning stations, and socialize, before embarking on night-time foraging missions. Scalloped Hammerheads are a shy species that will seldom approach divers, presumably due to the breathing noise and streams of bubbles. To minimize disturbance on this Critically Endangered species, small groups of tourist divers are carefully briefed prior to dives, and actively led underwater by trained guides. Divers are brought to suitable viewing areas, depending on the location of the shark schools, whereupon the divers take up static positions amongst the large boulders. This avoids disturbance to the sharks, as the guides ensure the dive groups do not approach the open-water cleaning areas at these sites, while the divers in turn get to unobtrusively observe the natural behaviors of the sharks.

Looking Forward

Shark tourism is a relatively new and fast-growing industry, with a low barrier to entry in many countries, that can quickly outpace management capacity. While the terms ‘‘shark diving ecotourism’’ and ‘‘shark tourism’’ are often used interchangeably, the word ‘‘ecotourism’’ implies that activities are ecologically sustainable, directly contribute to species and habitat conservation, and provide tangible benefit to the local community. Whether shark tourism can truly be considered ecotourism varies between sites and species; some sites meet this definition, but others do not.

There have been few “before” and “after” studies on shark tourism, and the recent development of many sites means there are few longer-term data available on community responses and successful management strategies. Assessing the likely impacts of these operations means dealing with high levels of scientific uncertainty across species, sites, and different operational situations. A high level of engagement with experienced operators will be useful, to understand practical issues and develop effective codes of conduct, along with regular reassessment as more information becomes available.

Many of the most important species in shark tourism are globally Endangered, and even Critically Endangered. None have been driven to this point by tourism. Shark tourism has had minimal impact on shark populations compared to overfishing, habitat loss, pollution, and climate change, which all pose significant threats. However, the precarious state of these species makes it important to avoid chronic impacts that can create additional stress on these animals. Increased interactions with boats, divers, and snorkelers will affect sharks and rays. The extent of these impacts, and whether they affect the welfare of the focal species, is dependent on management at the site, whether voluntarily applied or imposed by regulation.   

Some of the world's iconic shark preservation areas, such as Raja Ampat in Indonesia, the Galapagos Islands, and Tubbataha Reefs in the Philippines, are largely funded by shark tourism. Shark tourism can have demonstrable benefits, both in changing public perceptions for the better and incentivizing conservation initiatives. Unmanaged tourism, however, can quickly devolve into an additional burden on the focal species and their habitats. Going forward, if people are to benefit economically from threatened species, we need to ensure that the sharks and rays are benefiting too.

Further Reading

Sustaining marine wildlife tourism through linking Limits of Acceptable Change and zoning in the Wildlife Tourism Model. Bentz J, Lopes F, Calado H, Dearden P (2016) Marine Policy 68: 100–07. 

Emerging challenges to shark-diving tourism. Gallagher AJ, Huveneers CP (2018) Marine Policy 96: 9-12.

Biological effects, conservation potential, and research priorities of shark diving tourism. Gallagher AJ, Vianna GM, Papastamatiou YP, Macdonald C, Guttridge TL, Hammerschlag N (2015) Biological Conservation 184: 365–79.

A global review of elasmobranch tourism activities, management and risk. Healy TJ, Hill NJ, Barnett A, Chin A (2020) Marine Policy 118: 103964.

These articles on Human Threats To Sharks & Rays were originally written by Dr Simon Pierce in 2022 as fact sheets for the UN Convention on the Conservation of Migratory Species of Wild Animals, prepared by the IUCN Species Survival Commission (SSC) Shark Specialist Group, with funding provided by the government of Germany and the Principality of Monaco and with technical support from the Sharks MOU Advisory Committee. The direct link to the document, available in English, French, and Spanish, is here. Please note that the online text and imagery will likely have been altered from the original.