The truth is that very little is known about White Sharks. As there have always been very few sightings of them, it’s difficult to get readings on their numbers, habitats and habits. However, recent analyses suggest that their population has declined by between 52 to 96 percent from levels just over 100 years ago. They are listed as critically endangered and, according to the International Union for Conservation of Nature (IUCN), teeter on the brink of extinction.
And if great white sharks were to go extinct, we’d all be in big trouble.
As apex predators, sharks have a huge impact on the ocean’s ecosystem. Not only do they maintain the numbers of the species they feed on, such as sea otters and other fish, but are also vital to maintaining seagrass and coral reef habitats. Without them, other predatory fish would eat more herbivores, which in turn would allow algae to dominate over coral reefs. And, as well as over 25 percent of marine life’s dependence on them, over half a billion people also rely on reefs for food, income and protection according to the US National Oceanic and Atmospheric Administration.
Why is so little known about Mediterranean great white sharks?
The scarcity of knowledge about Mediterranean great white sharks can be at least partially attributed to the following factors:
1. Low population density: Compared to other great white habitats like Australia or South Africa, the population density of great white sharks in the Mediterranean is much lower. This makes studying them more challenging as encounters with humans are less frequent.
2. Historical bias: Historically, research on great white sharks has focused on regions where they are more abundant. This bias has led to fewer studies and less attention on Mediterranean populations.
3. Elusiveness: Great white sharks are known for their elusive nature. This is particularly true in the Mediterranean where they may roam over vast distances in deep waters.
Historical records and anecdotal sightings hint at a time when these apex predators roamed the Mediterranean in abundance. However, over the past five decades, their increasingly low population has plummeted. Why could this be? We’ll give you one guess.
The Mediterranean is the most overfished place in the entire world
“Great white sharks were, without a doubt, at one time much more abundant in the Mediterranean” Alessandro De Maddalena, Professor of Vertebrate Zoology and author of Mediterranean Great White Sharks: A Comprehensive Study, told National Geographic in 2021.
“This is not only true for white sharks, but there is also evidence showing that many species of sharks have suffered a strong decline in the past 50 years, [becoming] uncommon or rare as a consequence of overfishing either the shark or its prey.”
The Mediterranean Sea, once a thriving habitat for marine life, has become one of the most perilous zones for large oceanic predators, particularly the Mediterranean white shark.
Predictably, human interference is the cause of their declining numbers. Industrialised fishing in the Mediterranean, like in other parts of the world, has undergone significant changes over the past century due to advancements in technology and exponential demand for seafood.
In a 2018 report commissioned by the United Nations, the Mediterranean was identified as the world’s most human-depleted sea, with 62 percent of fish stocks marked as overfished. Obviously, this has a knock-on effect on the numbers of those animals which feed on them. While some regulations have been put in place in recent years in response to these extreme numbers, both general ignorance and the ambiguity of the parameters of international waters around the Mediterranean make imposing these tricky. Shark prey is continuously depleted, sharks themselves end up in nets, and even purposely (and illegally) caught for their lucrative body parts.
With human activity decimating their numbers, urgent action is needed. As always, gaining data on this critically endangered species is the first port of call.
Unlocking the mystery of shark number decline with data collection
A research project led by Dr. Francesco Ferretti and his team at Virginia Tech in the United States is locating and studying the last remaining white sharks in the Mediterranean Sea.
Shark Project, which began in 2021 and expects to run long-term, represents a collaborative effort involving multiple institutions and researchers across the US, Europe and beyond. By employing state-of-the-art technology such as environmental DNA (eDNA) sampling, baited remote underwater video systems (BRUVS) and drones, the team aims to unravel the mysteries surrounding the Mediterranean white shark. These techniques enable non-invasive monitoring to provide invaluable insights into the sharks’ spatial distribution and ecological dynamics.
What is e-DNA sampling?
Ever watched CSI? Instead of collecting actual plants or animals, scientists collect tiny pieces of DNA that living things leave behind in their environment. Just like how we shed hair or skin cells, animals and plants release DNA into the water or soil through things like saliva, urine, or skin.
Scientists can then take samples of water or soil from an area and analyse them in the lab to detect the DNA of different species that have been there.
This helps researchers figure out what kinds of plants and animals are present in an area without having to actually see them. It’s a useful method of studying biodiversity and monitoring ecosystems that’s also non-invasive.
A collaborative approach means more data points to work with
A key milestone in the project’s goals is the deployment of a satellite tag, a small tracking device, to track the movements of a Mediterranean white shark. The researchers use this unique information to study the shark’s behaviour, migration patterns and habitat. The use of these tags is groundbreaking—it’s the first time in history such a tactic will be employed in this area.
The researchers also leverage historical and recent sightings to identify potential hotspots within the Mediterranean Sea. The project aims to empower citizen scientists through SharkPulse—a platform dedicated to collecting shark sightings and photographs worldwide. These public sightings are vital. Through them, the researchers hope to gain valuable insights into shark populations and identify critical habitats for conservation. Their findings have revealed, for example, that the Sicilian Channel is believed to harbour a nursery ground for white sharks. Findings like these, alongside the presence of abundant bluefin tuna, a primary food source for sharks, offers a glimmer of hope for their survival.
The combined collaborative elements of Shark Project are designed to create the clearest picture yet of the Mediterranean great white. Once we understand their numbers, their habits and their habitats, we can better understand what’s causing their decline. The hope is then that conservation and management action plans, for example, improved fisheries regulations, can be suggested to ensure the recovery of the species in the region.
Shark Project seeks to establish a long-term research and monitoring program for Mediterranean white sharks. According to their website, the project is ongoing, however very little in terms of research outcome and much less policy change has been publically announced since 2022.
By fostering collaboration among scientists, NGOs, and policymakers, the initiative aims to safeguard the future of these iconic predators. But, although the data collected in projects such as these is vital for our understanding, as always, it’s the conservation measures and improved fishing regulations imposed by governments that’ll make the biggest difference to the recovery of the Mediterranean white shark population for generations to come.
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