Biologists are making strides to protect one of the most at-risk white shark populations in the world. A research team has spotted signs of these threatened sharks in the Sicilian Channel.
The Mediterranean Sea is a haven.
It features clear waters and stunning coastlines that are famous globally, touching on several continents.
However, within these beautiful, sometimes busy waters lurks a legendary species that faces a daunting future: the white shark.
Francesco Ferretti, an assistant professor at the College of Natural Resources and Environment, is dedicated to rescuing one of the most endangered white shark populations on Earth. The research team has detected traces of the remaining white sharks in the Sicilian Channel.
“We took on the mission to find the last white sharks in the Mediterranean and protect them,” Ferretti explained. “A key step was tagging individual sharks to understand their numbers and locations better. This led to the ‘White Shark Chase,’ a project where we began identifying regions in the Mediterranean where these creatures could be discovered. It was challenging, as these sharks are extremely rare.”
Indeed, they are incredibly rare.
Unlike locations such as California, where sharks congregate around seal colonies, no known gathering spots exist for them in the Mediterranean. Locating them felt like searching for a grain of sand in the ocean.
Taylor Chapple, an assistant professor at Oregon State University’s Coastal Oregon Marine Experiment Station, is a white shark technical expert on the project. He was a postdoctoral researcher with Ferretti at Stanford, and they have collaborated ever since.
“These sharks likely have distinct ecological behaviors compared to those from other parts of the world,” Chapple noted. “They seem to rely more on tuna and smaller fish as their food source. This changes our previous understanding of white sharks. It explains how these massive animals, weighing several tons and larger than any land predators, can thrive on a diet that defies expectations. While seals are very fatty, these sharks feed on tuna and still reach significant sizes.”
This research marks the first step towards establishing a monitoring program for white sharks in the region, as part of ongoing efforts to aid in the prevention of their extinction in the area.
The findings were published in Frontiers of Marine Science on October 22, 2024, in collaboration with various organizations, including Jeremy Jenrette and Brendan Shea from the Department of Fish and Wildlife; Shea and Austin Gallagher from Beneath the Waves; Chiara Gambardella from the Polytechnic University of Marche; Gambardella and Stefano Moro from Stazione Zoologica Anton Dohrn; Khaled Echwikhi from the University of Gabes and the High Institute of Applied Biology of Medenine; Robert Schallert and Barbara Block from Stanford University; Schallert from Tag-a-Giant; and Chapple from Oregon State University’s Coastal Oregon Marine Experiment Station.
Funding for this research came from The Explorers Club, Discovery Channel, Sharkproject, the Bertarelli Foundation, the Augmentum platform, and individual contributors.
In 2021, 2022, and 2023, Ferretti led three pilot expeditions targeting suspected hotspots for the species in the Sicilian Channel. These expeditions utilized enhanced methods and technologies compared to previous attempts, such as environmental DNA (eDNA) sampling, which utilizes traces of animal DNA in water similar to how a dog might scent an animal’s presence. The team also employed surface and deep-water cameras with bait to attract the sharks, along with chumming to draw them closer.
During these expeditions, the team observed white sharks on five occasions at four different sites. The team’s choice of times from May to June proved effective, although they were unable to interact directly with the sharks.
“They are incredibly rare, and we understood that even with our efforts, our scale was too small,” Ferretti acknowledged. “We need to rethink our strategies and develop new methods. Despite our challenges, we found a stronghold for this shark population, particularly in the southern Sicilian Channel near northern Africa. This area faces significant fishing pressure, and we will be focusing our initiatives there. The pilot expeditions helped us refine our approach for larger-scale programs and offered valuable insights for future explorations.”
Choppy waters
The research team, which included graduate students from Virginia Tech, used recreational boats for their missions. Although functional, these boats were not ideal for marine research since they lacked the necessary space, speed, and equipment to store chum material—mostly bluefin tuna, which is tightly regulated in the Mediterranean and not easy to source.
“We successfully carried out our research, gathering critical data for future missions,” Ferretti commented. “It was a demanding yet essential phase of our efforts to protect this endangered shark population.”
The team’s journeys took them from Marsala, located on Sicily’s northwest tip, to various islands, including Lampedusa and Pantelleria, as well as to Tunisia and Malta. They deployed long-line cameras and collected eDNA samples along the way. However, heavy commercial boat traffic and fishing activity in the Sicilian Channel presented significant obstacles, necessitating careful monitoring of equipment to avoid accidents with passing ships.
In 2023, the team switched to a large 87-foot sailing yacht to conduct research in open waters, accompanied by a film crew documenting their mission.
While they did not sight any white sharks directly, they successfully tagged a Mako shark for the first time in this region as part of another research initiative.
Ferretti noted that future research missions are planned and outlined.
The next frontier
Currently, the research team is planning and raising funds for multiple upcoming expeditions in the Sicilian Channel and other areas.
“We know a hotspot exists, but other significant regions in the eastern Mediterranean Sea may also provide vital habitats, such as nurseries,” Ferretti pointed out.
The researchers are launching various strategies, including monitoring ports in North Africa to observe interactions between fishers and sharks and gather biological samples. This will enable them to collect genetic and isotopic data for analysis. By examining isotopic compositions, they can gain insights into the population structure, dietary habits, and habitat changes as the sharks mature.
“Our research is not conducted in isolation,” Chapple remarked. “Today’s multi-disciplinary approach allows us to address questions that previous single-faceted methods cannot. This white shark initiative taps into valuable insights from local communities and stakeholders; as scientists, we cannot simply dictate what should be done. Collaborative efforts across institutions are vital for grasping the complexities of these animals, their environments, and the cultural contexts surrounding the research.”
These collaborations across universities and regions enhance the researchers’ abilities and effectiveness.
“We are broadening our network of local and international partners to maximize the impact of the data we gather and establish a comprehensive monitoring program for the Mediterranean,” Ferretti stated. “Currently, there is no official monitoring or conservation program for this shark population. Our goal is to continuously monitor their numbers because we cannot afford to lose them.”
