With an increasing interest in the natural world, the adventure tourism industry is experiencing extraordinary growth. The foundation of many of these tours is an attraction to view wild animals. From nature parks and game reserves to predators of Africa and the Arctic, these tours are popular. This interest in wildlife is also extending into marine ecosystems, as aquariums with sea life have been increasing in popularity. The dolphin swim with live encounters industry has exploded in popularity, as has the cage diving industry worldwide. This is evident not only from the increase in the number of outfits, but also the number of people they are taking out to try and witness one of the iconic species – the great white shark.
In 2001, more than 100 vessels registered to watch sharks at a key aggregation site. The experiment conducted at a specific location showed that white sharks are sensitive to the approaches of cage-diving boats. The issues surrounding these kinds of activities are diverse, yet little scientific evidence is available upon which informed research can be conducted. This research provides insight into some of the potential impacts of cage diving. Furthermore, despite the growing interest, adventure-type tourism is not without its problems from a conservation perspective. Many of these human-animal interactions are ill-informed and can be damaging to the resource. This raises the question: does an increasing demand for tourism in natural settings mean that we must accept that human activity may no longer be constrained?
Background and Significance
Couplings and interactions between human and animal behavior have presented a topic of increasing interest in recent years. In the field of wildlife tourism, extending beyond the conclusively documented impacts on imperiled primate species to date, great white sharks have emerged as a species of particular intrigue. Shark-human interplay in this setting characterizes an intimate bond, added as the composite thrill of adventure and wildlife observation typically offers a potent juxtaposition.
It is now acknowledged that sharks are not the ravaging beasts once assumed. Rather, sharks are now realized as essentially dedicated, efficient, opportunistic predators. Outing further their ecological value, shark populations inherently harbor an intrinsic value. It is warned that mankind underestimates the interest of these coastlines. Indeed, today the tourism-raising great white shark constitutes an important and growing interest and can, without doubt, become huge earners for local communities because they can offer boat-based tours and dives for both intrepid and casual shark watchers. Yet, precisely while the two shark-experience operations present obvious opportunities, they simultaneously represent potential risks.
Several studies have candidly addressed the way in which commercial and recreational dives with, respectively, whale sharks and nurse sharks can impact shark behavior on a variety of dimensions. Analyzing the potential impacts which may be associated with ‘cage diving’ with great white sharks, this study posits a variety of motivations for and consequences of this new marine tourism activity. Since the first ‘recreational’ dive was established, studies have linked this predatory activity to a variety of societal motives and supposedly further negative behavioral responses.
Cage diving tourism has been an ever-growing wildlife tourism industry that currently involves at least 24 countries. The conservation values associated with this practice are controversial without a solid scientific understanding of its impacts on wildlife.
Ecological Importance of Great White Sharks
Great white sharks are apex predators and therefore are of importance to the marine ecosystem. One characteristic of apex predators that makes them stand out is their key position in the food web. The removal or decline of these species can lead to significant alterations in ecological variables such as biodiversity, behavior, population numbers, bottom-up ecological control, prey distribution, and abundance. Large numbers of prey can prevent individual predators from squandering energy on hunting instead of foraging. Great white sharks have a smaller sex ratio group, and even though they are slower growing than many other shark species, they are apex predators while young, which could suggest a steadily increasing regrowth rate. The high age at maturity also embodies universal ecological value, which supports local conservation actions that could, in turn, support global marine conservation efforts.
The ecological role of large sharks has been an important research topic for several years, as it has been confirmed that the removal of large sharks can induce trophic cascades. Predators play an integral part in maintaining ecosystem equilibrium and regulating prey populations. Food web dynamics are controlled by interspecific interactions among populations living in one habitat. Large predators contribute to energy transfer and nutrient cycling within the trophic pyramid and assist in general trophic tonality. As such, a severe decline or extinction of great white sharks might affect diversity, abundance, and the distribution of other marine species, which could result in local extirpation. Furthermore, dangling prey, including marine mammals, could result in an unacceptable predation regime that might pose a risk to human welfare. Recognized as ecotourism flagships, great white sharks make a considerable contribution to marine conservation.
Role in Marine Ecosystems
In addition to scientific curiosity, recent public interest in great white sharks has been focused on cage diving tourism. However, they are also currently listed as a potentially vulnerable species, therefore protecting them is of the utmost importance. Deeming their role in marine ecosystems important gives an inclination to their preservation, along with interest in their behavior, physiology, and ecology. Great white sharks are top predators in marine ecosystems. The position of an apex predator implies that their role is that of controlling populations of other species, beginning with their prey. Hence, the top predator role is essential for maintaining biodiversity through its influence over trophic levels as an upper-limit predator in the food web.
Apex predators prevent at least some prey from becoming too abundant due to predation, by influencing prey population size and individual prey interaction behavior. The direct influence of prey population numbers prevents individual prey from overpopulating, monopolizing resources, and placing excessive predation pressure on other species. Thus far, the literature overwhelmingly supports a link between population size and a top predator’s role. The potential link between predation and the modification of prey foraging area and behavior, with further implications for prey population size, is also demonstrated in the literature. Habitat use and the distribution and abundance of some prey species appear to be influenced by sensors for conspecific presence, and food resources can be seeded in water in the lonely shark experiment. Essentially, the prey surfing strategy lessens the total amount of energy, time, and risk in order to find food and may have profound ecological implications for other marine life. Given both these findings, sharks can indirectly influence marine systems by helping to maintain healthy habitats. These observations suggest that sharks might have ecological roles that might not be directly related to direct consumption of their prey, but instead lie in preventing overpopulation. Interestingly, apex predators can control parasite and pathogen density, with implications for protecting healthy ecosystems and diverse biomes. Another potential role is that great white sharks can influence the genetic diversity and evolutionary adaptation of prey populations through predation selection. Furthermore, the absence of a top predator can have far-reaching ecological consequences in the form of trophic cascades, with deleterious effects on ecosystems. Although great white sharks may not be primarily responsible for eliminating overpopulated prey species through consumption, as do some apex predators, some have put forward such a linking untested hypothesis. It has been suggested that while a top predator may not always directly eat some species of prey, it can change the population size or behavior of that species in such a way that it has important and far-reaching influence. In light of and with the hope of further investigations on the subject matter, we maintain that these reasons make the case that great white sharks play an influential and crucial biological role in marine ecosystems.
Cage Diving Tourism: Practices and Trends
Cage diving tourism at present is experiencing a significant expansion in popularity. The fascination of white shark tourism is fully apparent when considering shares in two of the longest established cage diving tourism companies in the world, at the Neptune Islands in South Australia. Between 1986 and 2006, share prices of one company rose significantly. By 2008, the other company had over 6,400 shareholders. Strong demand for cage diving tourism is further demonstrated by a range of new businesses globally that have begun offering this experience. In South Australia, one operates in Port Lincoln and one in the smaller regional community of Whyalla, some 300 km from the primary tourism departure point, as well as a non-caged viewing boat. In Tasmania, a boat offers cage diving tours that include other wildlife and seabird tours. At least 13 eco-tourism boat trips operate with white sharks to great effect in New Zealand, along the coast of South Africa, one based in Mossel Bay and the remainder in Gaansbaai and two cage operations in Mexico at Guadalupe Island.
Cage diving tourism occurs in a remote location, at sea, primarily during winter months and is, therefore, relatively inaccessible to seasonally transient inhabitants of the regional city from which cage trips operate. Visitor numbers for great white shark tourism actively engaging with the sharks in some manner ranked highest after blue and mako sharks in a pilot study at two local charter boats operating from the Port Lincoln marina. According to survey participants, use of rented gear has also increased significantly by visitors to and from the Eyre Peninsula in rural South Australia who traveled in the past 12 months as a proportion in the last 12 months compared to the previous 5 years. Overall, each year thousands of tourists engage with white sharks in some manner at Australian and international sites. Cage diving tourism revolves around the reliable, close encounters with great white sharks in the wild, primarily by boat. Tourists are submerged in large surface steel or aluminum cages smaller than the hull. The cage may be deployed with baits, attracting the sharks close. Tourists, primarily adults, use marine animal operator-sourced wetsuits and masks, as well as diving regulators. The metal dinghy and cage act as floating berley pots so that great white sharks, unless temporarily antagonized, display a range of natural behaviors to onboard participants. The respective methods of charter boat companies ensure underwater profitability, guest safety, and that wildlife are not crowded and do not become so habituated to humans that they treat divers as food. Vibrant and animated in the water festivals, vendor to consumer diver sights, and attractions based on a non-solitary attitude are more likely to appear when cage diving alongside white sharks.
History and Evolution
Cage diving tourism is a relatively recent occurrence and has only gained extensive popularity over the past two decades. Thus far, there is, however, limited literature regarding the potential impacts of these activities on great white sharks. Over time, the activity of shark cage diving has also evolved into different facets that include tourism, research, and commercial industries with illegal extensions. Shark cage diving has become a multimillion-dollar industry in South Africa with an increasingly active and expanding domestic and international tourist market despite the ongoing controversies and the recent withdrawal of companies from the industry. The industry has also seen years of various research projects being conducted purely for further understanding of great white sharks and the economic industry structure and drivers regarding shark cage diving with professional divers. The regulatory and management confusion glimpsed in the white shark industry in South Africa is representative of the confused status of a number of marine activities.
Tourism has been described as a dynamic system, and enterprises are dependent upon the evolving and changing demographic, economics, socio-political, environmental, cultural, aesthetics, and other variables mapping the demand-side phenomena. Although the origins of shark cage diving in South Africa might be traced back to the 1970s, the cage diving as we now know it used to be a relatively low-impact activity with limited boats operating throughout South Africa’s coastlines until the expansion, which raises questions about the sustainability of great white shark cage diving. Changes in the public perception regarding great white sharks partly resulted in the expansion and correspondent demand growth of adventure tourism in various tourism destinations around the world. The effect and current literature regarding public perception have it that these large sharks inspire both fear and fascination among the human population, transcending across global populations. This has fueled a range of shark-oriented niche adventure activities, holiday experiences, and a number of broader cultural imprints that include movies, everyday language, television shows, popular literature, and music.
Popular Locations
Great white sharks are present worldwide, and while they are observed at levels lower than temperate areas, they are swimming around the waters of many countries near the tropics. Many divers are fascinated by these powerful predators, and diving experiences that involve entering a cage and being lowered to 10-12 m in the sea are very popular at some tourist sites worldwide. Gansbaai, in South Africa, about 160 km southeast of Cape Town, bills itself as the white shark capital of the world, and it is home to the densest population of great white sharks in the world. As a result, it has the highest rate of white shark tourism in the world, and many diving companies have operations in Kleinbaai harbor. Isla Guadalupe, 314 km southwest of Ensenada, Mexico, is one of the best places in the world to dive with great white sharks because it offers excellent visibility, easily accessible sharks, and calm seas.
Gansbaai and Isla Guadalupe may represent the two most distinct places in the world to see great white sharks and may be representative of many of the most popular places for cage diving with great whites. Though white sharks are seen in waters off many tourist locations, they are observed in large numbers and are attended by many operators at Gansbaai and Guadalupe, drawing the most attention from divers. The number of operators and the amount of diving at both places are testimony to the sharks’ reliability; aggregations are beyond normal for the species and are the result of baiting and possibly other attracting behaviors. Both places were likely made particularly popular by the sheer number of sharks at them. Fish and aquatic animals are attracted to certain local sites because the geography, currents, and many other factors that are more or less beyond human control provide suitable habitat. Moreover, both places draw some of the biggest great whites in their regions and some of the most dramatic predations. Isla Guadalupe is noteworthy because the native sea life, including elephant seals and Guadalupe fur seals, are a staple of the diet of great whites, and so shark predation on pinnipeds is much more consistent.
Impacts of Cage Diving on Great White Sharks
With the growing popularity of cage diving tourism in different parts of the world due to possible financial gain and public education benefits, it becomes increasingly important to understand any potential impacts on the focal species. Understanding the direct and indirect effects of human activities, which are likely to impact the physiology and behavior, is important for animal welfare and for considering the long-term success of shark tourism and potential flow-on effects on our business and long-term vision of coast-to-coast marine reserves. Yet current knowledge is relatively limited about the impacts of cage diving on the behavior and physiology of great white sharks and their interactions with conspecifics. Changes in shark behavior due to cage diver tourism suggest a range of potential behavioral responses, including changes in the percentage of sharks approaching bait, bites on the bait, and the duration and types of interactions occurring between sharks and pinnipeds. Cage divers are sometimes concerned about orcas arriving at the shark boats, which can be associated with changes in the behavior and movement patterns of white sharks. Stress and physiological costs of tourism interactions have broader implications for white sharks. At Guadalupe Island, where white sharks are physically close to the cage diver, it has been suggested that some sharks start to exhibit so-called shark fatigue, which may derive from repetitive and close interactions causing some avoidant behavior.
Behavioral Changes
The findings of recent studies suggest that the long-term presence of cage diving tourism has resulted in behavioral changes in great white sharks that use such areas. One obvious behavior change that has already been described in this text is the shift to the use of beach-seal predation rather than frequenting the island seal colonies. However, other types of behavioral shifts have also been recorded, such as changes in movement behavior and territory use. This study therefore aims to determine whether long-term cage diving tourism and provisioning in the Gansbaai study area influence the fine-scale movement and residence time behavior of great white sharks in general, irrespective of activity type.
It is acknowledged that great white sharks may change their activity level in response to regular interactions with divers on a more acute time scale and that it is therefore possible that great white sharks do spend less or more time around shark diving vessels. Interestingly, the interaction between pinnipeds and great white sharks has attracted a plethora of attention from the scientific community, mainly due to the large number of opportunities it presents for the study of predator-prey interactions as well as predatory behavior from an ethological perspective. It is important to understand that although sharks around shark diving vessels are shown to spend a larger amount of time near vessels, the sharks appear to do so deliberately and are not attracted to the vessel in the same way that many other marine animals are during feeding. The suppression of fear leads to habituation, and wildlife in its natural unaltered state would typically have a fear response to anthropogenic sounds or disturbances, leading to increased stress and potentially altered movement patterns for long durations.
Physiological Effects
Determining the physiological responses of animal populations to different management techniques is a useful tool in deciding whether a given activity should continue or needs adjustment. Sustained physical stress can lead to both temporary and long-term negative physiological effects and can be used to assess the impact of cage diving tourism on great white sharks. Longer-term physiological changes that could lead to reductions in health and reproduction can be investigated by examining various hormones, energy reserves, temperature, osmoregulatory, haematological, immune, metabolite, protein, and enzyme levels. Hormone levels in sharks could be monitored using haemolymph obtained non-lethally in the field or using blood plasma in the laboratory.
Some physiological responses, such as increased heart rate, surface body temperature, and blood glucose levels, have been observed as sharks approached bait during and after chumming. This trend was especially evident in females, which are likely more susceptible to stress during fasting periods due to increased energy expenditure in ovogenesis. These were suggested to be initiated not only by the presence of the same environmental pressure, but also by the repetitive tours, active and passive swimmers at the surface. Reduced, nervous, or defensive behavior in artificially baited animals has implications for human safety and should be avoided. Within some systems, immune system responses, including changes in resistance to and rate of infection by parasites and pathogens, can also be measured and can help determine the presence of a physiological stress response. Greater susceptibility to infections and parasites brought about by a reduced immune response, as well as higher rates of predation and/or reproductive energy allocation, could result in a decrease in the ability to reproduce or long-term accumulation of negative effects leading to population-level consequences such as mortality rates. Guidelines for best research practices with wildlife indicate that the most important first step in validating a biomarker is to elucidate the potential naturally occurring, relevant stressors, such as environmental factors that serve as the sources of sublethal stress in wild individuals. In order to interpret Coral Bay results, it is vital to understand what the overarching physiological parameters at risk are.
Mitigation Strategies
As highlighted in the previous section on tourist effects, there has been a backlash against shark tourism because of the negative impacts it can have on shark populations and marine ecosystems. This proactive approach is aligned with the principles of sustainable tourism and is advocated on the basis of a ‘precautionary approach,’ which suggests that the lack of negative effects on ecosystems should be tested before, rather than waiting for detectable long-term effects as evidence.
Shark cage diving activities can have potential impacts on both wildlife and habitat, and it is important to ensure that the management of the industry is conducted in a responsible and sustainable manner. Policy and management guidelines need to be in place and enforced prior to the onset of shark cage diving. For new areas, shark cage diving should only be allowed if strict conditions are met. For all areas, the safety of the viewing tourists is of primary concern. Although valuable in areas where the tourist industry is heavily based on shark cage diving, night operations are considerably more dangerous, and such excursions must be conducted as a joint-boat operation where a ‘mother ship’ supports the cage diving vessel. The precautionary principle is applied to the chumming of sharks at the sea surface, as it can attract sharks for tens of kilometers to the area of operation. For this reason, chumming of sharks in areas prone to shark attacks, such as near popular bathing beaches, must be strictly regulated. Cage diving cannot take place closer than 50 m from the shore. The most appropriate way to implement a management system would be to control the operation of cage diving vessels by way of a licensing system that is incorporated under national or provincial legislation. Approval of such a license should be preceded by an environmental assessment by the conservation services of the relevant province or country, to ensure that there are no unacceptable adverse impacts on the environment. The license should contain specific guidelines for operators, in addition to general legislation. Educational brochures can be circulated to both shark viewing tourists and tour guides to further encourage responsible ecological viewing. Law enforcement is, on occasion, called to act in instances of reckless behavior. All shark cage diving operators are overseen and policed to some degree by the appropriate authority to ensure that the guidelines are adhered to.
Regulatory Measures
Cage diving tourism, specifically with great white sharks, is an exciting wildlife encounter for conservation and tourism purposes. However, there is the potential for this growth to have detrimental ecological and ethical implications if not overseen effectively. Given the unprecedented growth of great white shark tourism in the western world over the past few years and the trends of shark population decrease in response to global fishing mortality, there is an overwhelming need to establish regulation and control around this controversial activity. Currently, it is strictly up to the dive operators themselves whether a chum line is used to attract sharks, and if so, how potent the chum mixture is. Local authorities do not enforce diving companies to not use chum, although fines may be imposed on individual circumstances. Information has been collected from all licensed cage diving companies in South Australia that has provided evidence of the presence and use of shark attractants in the large majority of tours. Strict enforcement around the use of shark attractants is seen as an ecological necessity by many members of the South Australian public.
In order to effectively govern this activity and ensure its ecological sustainability, it is first necessary to have regulations in place that define in objective terms what the tour companies are allowed to do. Many examples of chum attractant usage exist around the world for the purposes of appealing to eager tourists. Although there are no worldwide comprehensive regulations in place to provide ecological safety to these practices, there are a number of guidelines outlined for tourism operations on board vessels to view wildlife from a safe distance. Enforcement of these guidelines is largely up to governing bodies not taking full responsibility for the industry. Controls to mitigate the ecological impact on target species in Southern Australia could be implemented through the use of a licensing system for the attraction of these species, where the number of trips per day, months of the year, and the use of bait are stipulated. In South Australia, legislation could be enacted by aligning it with the Adventure Activity Standards Australian Standard to Aquatic Tourism – Viewing Aquatic Wildlife. Regulatory measures such as tour site allocation, time restrictions, and reductions in the number of dive operators have recently been proposed to protect grey nurse sharks at provisioning aggregation sites in New South Wales. Shark feeding ordinances apply for the protection of both humans and sharks.
Best Practices for Sustainable Tourism
Among stakeholders in great white shark diving in particular, there is a strong belief that best practices do exist, and it is possible to educate tourists in such a way that their psychological dependence changes to a less harmful form of use. This work showed that the runtime duration of trips, the number of tourism boats on the water, bait-handling procedures, the type and amount of bait used, and the distance to the chosen habitats are critical management areas to address to promote sustainable tourism. In general, best whale-watching guidelines are adequate to determine an appropriate distance for white sharks to whales, which allows at least 100 m between operators and will limit changes in shark physiology. It may also assist in controlling the physical habitual behavior changes. Key shark diving best practices that may improve eco-tourism and shark-viewing behavior were also drawn from studies on the detrimental effects of chum on coral reefs. These practices included operating on a pre-booking basis, reducing and banning chum used in and on diving boats and bars, servicing the diving chum disruption module regularly with non-corrosive, biodegradable chum, enforcing an eco-friendly diving protocol consistent with suggestions and diving guidelines, and monitoring sharks for unnatural behaviors and health checks. We can also exclude chumming another diving boat already in operation without first consulting that skipper. These best practices were adapted for non-pelagic boat-based white shark diving in South Africa.