Examining The Effects Of Humans On Whale Shark Behavior

Despite their ecological importance, sharks face one of the highest extinction risks among vertebrates, with more than a third of shark and ray species currently at risk of extinction, according to the International Union for Conservation of Nature. Overfishing is a primary driver of this decline, exacerbated by the life history traits of sharks, including slow maturation and low reproductive rates. Climate change and habitat destruction are also contributing factors in some populations. The magnitude of these threats and limited public awareness have historically impeded conservation efforts. However, there is a gradual shift in public perception, with growing support for shark protection.

One positive aspect in changing public perception is shark ecotourism, where individuals pay to interact with wild sharks, offering a chance for tourists to walk away with a more favorable image of these creatures. This industry has seen significant economic growth, estimated at over $300 million globally annually, and has created thousands of jobs. However, the ecological impacts of shark ecotourism remain poorly understood. Some evidence suggests that ecotourism activities, particularly those involving provisioning, can influence the abundance and composition of shark species and may trigger mesopredator release, ultimately altering lower trophic level species’ abundance. Even without provisioning, disturbances and boat-related injuries pose substantial threats. One of the most critical ways that shark ecotourism could impact sharks is by influencing their behavior. Behavior directly mediates inter-species interactions and can have profound downstream ecological effects resulting from human interference. Behavioral plasticity may also play a vital role in population-level resilience to environmental changes. Some studies have attempted to investigate the effects of ecotourism on shark behavior, reporting changes in foraging activity, long-distance migration, and avoidance/disturbance responses. However, these studies often yield conflicting results and lack standardization in behavioral assessments.

In a new study, researchers have used Unoccupied Aerial Vehicle (UAV) videography to explore how interactions between sharks and humans affect shark behavior, focusing on whale sharks (Rhincodon typus) as a case study. These gentle giants can grow to lengths of up to 60 feet (18 meters) or more and can weigh as much as 20 tons. Despite their enormous size, whale sharks are filter feeders, primarily consuming plankton, small fish, and other microscopic organisms by swimming with their mouths wide open to capture prey. They are characterized by their distinctive checkerboard-like pattern of white spots and stripes on a dark background, which is unique to each individual and helps with identification. Whale sharks are found in warm oceans and seas around the world, often near the surface where they bask in the sun. A popular subject for ecotourism, they draw divers and researchers from around the globe to witness their majesty up close.

Scientist Joel Gayford and his team analyzed 39 aerial videos of whale sharks in Mexico’s Bay of La Paz to see if the presence of a swimmer mimicking ecotourist behavior influenced the sharks’ actions compared to when they swam undisturbed. Their drone observations indicated that the sharks displayed more disturbed behavior when swimmers were present, with the sharks expending extra energy compared to their solitary swimming. This behavioral shift could potentially hinder their ability to find food and might even affect their chances of successful reproduction. These findings, published in Scientific Reports, suggest that operators of shark ecotourism activities should consider evaluating the behavior of individual sharks before allowing tourists into the water. “In light of these results, we suggest that the initial behavioural state of individuals must be assessed prior to in-water ecotourism activities, and that regulations regarding the minimum distance between human and shark should be revisited and reviewed in detail,” the authors wrote. “In particular, we suggest that sharks engaging in rapid, angular movements should be avoided.” The researchers also emphasize the need for more studies to fully understand the ecological impact of shark ecotourism on various shark species, highlighting the importance of responsible and sustainable practices in this industry.

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