Have you ever thought about jumping into a cage and seeing great white sharks (Carcharodon carcharias) in their own territory? You wouldn’t be alone! Ecotourism with these animals occurs in several countries around the world, including South Africa, Australia, New Zealand, the United States of America, and Mexico.
Thousands yearly flock to these locations to catch a glimpse of Jaws in action. Known as the largest predatory fish in the world, these torpedo-shaped animals are famous for their looks and ability to breach out of the water. Yet relatively little is known about its biology. With an estimated maximum size of about 20 feet (6 meters), they can maintain a body temperature that is higher than the surrounding waters, allowing them to venture into cooler waters.
You won’t see this species in an aquarium! Due to national and international wildlife regulations, shark cage diving is currently the main legal activity to get a face-to-snout encounter with this vulnerable species. In Mexico, cage diving began in 2001 and took off in Guadalupe Island, a volcanic island located off the west coast of México’s Baja California Peninsula. World renowned for its clear waters and numerous white sharks, ecotourism operators work during the “season” (between August and November) to provide both public education and scientific research opportunities. The local revenue of cage diving in Guadalupe has been estimated at more than $4.5 million dollars (USD) per season!
While the presence of the ecotourism operators provides ongoing surveillance against illegal fisheries, and the experience allows people to see white sharks as something other than a “mindless killer,” this industry is controversial. Why? Their methods. As the authors of a new cage diving study stated: “Provisioning of food has been linked with potential negative effects on habitat use, surface behaviour, bioenergetics, conditioning and a probable increase in the frequency of interactions with humans.” Since 2016, there have been at least six accidents related to cage diving at Guadalupe Island, where white sharks and divers have been injured. The most serious accident is when a shark died after being stuck in a cage for more than 25 minutes in late 2019, causing uproar worldwide about baiting practices. The limited vigilance in this remote region, along with a lack of evidence supporting some of the unfollowed regulations, have been said to be the cause for these accidents.
Online, many pointed to baiting as the sole problem. While only frozen fish (Thunnus albacares) bought in the departure port is allowed during ecoutourism ventures in this marine protected area, some use fresh bait believing it “could attract sharks more efficiently.” So, researchers, led by scientist Edgar E. Becerril-García of the Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas and Pelagios Kakunjá, decided to describe the effect that different baits have on the attraction, surface behaviour and conditioning of white sharks in order to prevent future accidents. During the study period (87 days), a total of 6,145 sightings from 121 identified white sharks were registered. The sharks were largely male (74%) with no statistical differences between maturity stages along the studied months.
“One of the most important points of the study consisted in evaluating the effect of baits (yellowfin tuna) on the surface behavior of the white sharks,” said lead author Edgar E. Becerril-García. “Our results made it possible to detect aggressive displays in certain baiting conditions, for which we made recommendations to improve diving activities and reduce the probability of incidents between sharks and cages.” The scientists found that success rate for the capture and consumption of bait was similar for all sharks, although it tended to be higher for male sharks and mature individuals (e.g. proportionally, a mature shark would get the bait 22 times for every 100 foraging attempts). The study also saw that the behavior of white sharks was significantly different depending on the type of bait.
“This research allowed determining a low risk of conditioning of white sharks towards cage diving boats, so it was not all bad news,” said Becerril-García. “It is important to highlight that Guadalupe represents the most important site for cage diving in the Eastern Pacific, so constant monitoring of this top predator is extremely valuable and necessary.”
As a cosmopolitan species that is economically exploited in several countries, the presented results of this study could be useful in not only future comparisons with other populations but contributing to efficient protection and sustainable use of the sharks. Afterall, we want to keep these sharks safe for future generations to enjoy them as well!