The great white shark is officially threatened with extinction, because of us. Estimated the trend of its presence in the Mediterranean. With sad results
He is about to end up run over, his mother saves himThe great white shark is officially threatened with extinction, because of us. This is demonstrated by an international study led by the La Sapienza University of Rome, which estimated for the first time the trend of the presence of the king of sharks within the basin over the last 160 years. With disturbing and very sad results.
The white shark has inhabited the Mediterranean for centuries (as demonstrated by numerous stories and famous films), with historical evidence of its sightings dating back to the Middle Ages. Unfortunately, however, its population has shrunk and, once again, the causes are mainly in human activities.
It is actually not new that this species is endangered: the International Union for the Conservation of Nature (IUCN) had already reported the situation and included the species among those critically endangered in the Mediterranean.
But so far no precise estimate had been made, both of the numerical trend of the specimens with respect to a reference period, and of their distribution in the different areas within the basin.
Photo: La Sapienza University of Rome
The research team managed to draw a picture using more than 700 reports of white sharks coming from institutional databases and literature, both scientific and popular, with recent sightings. Demonstrating a progressive increase followed by a rapid decline which took place from the second half of the twentieth century.
"The decrease - Giovanna Jona Lasinio explains, co-author of the paper - did not occur uniformly within the basin: for example, in the central Mediterranean there was a reduction of 52%, while in the Sea of Marmara it reached 96%. Furthermore, the decrease is often accompanied by one reduction of occupied spaces, a signal associated with populations at risk ".
The research constitutes a milestone for ecology, say the experts, because it allows to formulate new hypotheses on the dynamics of the white shark population of the Mediterranean Sea, including the prey-predator relationships involving other species, in particular the bluefin tuna.
And, unfortunately, human activities are the main cause of this situation, which risks having very serious repercussions on the entire ecosystem: in fact, the shark is at the top of the marine food chain and therefore has no natural predators (apart from humans). This means that its scaling is likely to have disastrous impacts.
“It has been proven - he explains in this regard Stefano Moro, who collaborated on research - how the removal of apex predators within marine ecosystems leads to disastrous top-down effects that si they affect the entire food chain. The Mediterranean, from this point of view, represents a negative record on a global scale, with more than 50% of shark species classified as “threatened” by the IUCN at the regional level ”.
A record that, honestly, we would gladly do without.
The work was published on su Fish and Fisheries.
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