Researchers have found the Mediterranean’s last white sharks in the Sicilian Channel.
The traces of the endangers great predators were found in the area during a number of expeditions led by Francesco Ferretti, an Italian scientist with Virginia Tech University.
The journeys took the team from Marsala, on the northwest tip of Sicily, to various islands such as Lampedusa and Pantelleria as well as Tunisia and Malta, deploying long-line cameras and collecting eDNA samples along the way.
However, the intense commercial boat and fishing traffic in the Sicilian Channel made things challenging, and the researchers had to monitor their equipment closely to avoid collisions with ships.
In 2023, the team utilized a large 87-foot sailing yacht to conduct open water research and had a film crew document the mission.
While researchers did not directly see any white sharks, they successfully tagged a Mako shark for the first time in the region as part of another research project.
Though they were historically abundant and widely distributed in the region, Mediterranean white sharks have declined to dangerously low abundance levels, impacted by centuries of coastal and, more recently, industrial fishing.
“We decided to accept the challenge of finding the last white sharks in the Mediterranean,” Ferretti said.
“It wasn’t easy”.
Unlike places like California, where the sharks gather near seal colonies, they have no known aggregation areas in the Mediterranean. Finding them felt like searching for a needle in a haystack, or more aptly, a grain of sand in the sea.
Taylor Chapple, assistant professor at Oregon State University at the Coastal Oregon Marine Experiment Station and white shark technical expert on the project, was a postdoctoral scholar with Ferretti at Stanford University and they have continued to work together ever since.
“These animals likely have a very different ecology than the white sharks from other global populations,” Chapple said. “These seem to be more likely based on tunas and smaller fish. It almost flips our understanding of white sharks on its head. It allows these animals that are a couple of tons — bigger than any land perdators — to exist on a resource that is very surprising. Seals are very fatty, and these sharks are feeding on tuna and still getting this large.”
Ferretti organized three pilot expeditions in 2021, 2022, and 2023, focusing on what they believed to be hotspots for the species – the Sicilian Channel. These expeditions used improved methods and technologies compared to previous efforts, such as environmental DNA (eDNA) sampling, which detects traces of animal DNA in water, like using a dog to sniff out an animal’s presence. The researchers also used surface and deepwater cameras with bait to attract the sharks and chumming to try and lure them closer.
During the expeditions, they detected the presence of white sharks on five occasions at the four sites. The team was correct in its choice of location and timing of May through June but did not interact directly with the sharks.
“They are extremely sparse, and we realized that even with our efforts, we weren’t working on a large enough scale,” Ferretti said. “We need to recalibrate our approach and develop new strategies.
Despite these challenges, we were able to identify a stronghold of this population, particularly in the southern Sicilian Channel off northern Africa. This area is highly impacted by fishing, and it is where we are focusing our efforts now. The pilot expeditions allowed us to recalibrate for a larger program and provided valuable insight into where to focus future efforts.”
The study seeks to be the first step of a conservation program in the Mediterranean to track the last white sharks in the region, estimate their abundance and extinction risk, characterize the species’ ecology and inform management and conservation.
A paper on the study, which also featured contributions from the Università Politecnica delle Marche and Naples’ Anton Dohrn Zoological Station, has been published in Frontiers in Marine Science.
Read more via Virginia Tech University/ANSA/Frontiers in Marine Science
