Aberdeen University find great white sharks more at risk of extinction than realised
Researchers found the sharks are not interbreeding between groups
Great white sharks could be more at risk of extinction than previously thought, according to researchers at the University of Aberdeen.
They found the sharks are split into three separate groups, who cannot interbreed, increasing the risk of becoming endangered.
One group can be found in the southern Pacific Ocean (Indo-Pacific), another in the North Atlantic, and the third in the Mediterranean.
With each group rarely interacting with another, each lineage is much smaller, and unlikely to make up for a shortage of numbers in another.
"Unique genetic diversity would also be lost"
The university’s Dr Catherine Jones led the research, in partnership with teams in Oslo, Potsdam, Florida, Italy, and South Africa.
She said the divide in populations appears to have come towards the end of the Penultimate Ice Age, between 100,000 – 200,000 years ago.
Dr Jones added: “This separation can still be observed today as modern major ocean currents seem to act as boundaries of the areas occupied by each group.
“If all the white sharks belonged to a single large, integrated global population, it would not matter so much if they vanished from a specific area.
"Man's future is increasingly bound up with that of white sharks"
“But if white sharks comprise separate genetically distinct populations, such as in the Mediterranean, and this were lost, unique genetic diversity would also be lost.”
Researchers say understanding the distribution and health of these distinct groups is key to future protection of the species.
Professor of Aquatic Biosciences at Nord University in Norway, Les Noble, who also holds an honorary position at the University of Aberdeen said management units for white sharks have not been available until now as they were assumed to be a single global population.
He added: “Although not widely appreciated man’s future is increasingly bound up with that of white sharks.
"White shark abundance has almost halved"
“As top predators they play a crucial role in maintaining the health and diversity of local marine ecosystems which are responsible for 20% of protein in our diet.
“In the last 50 years white shark abundance has almost halved, and it is recognized as critically endangered in Europe.”
Dr Jones said: “It has long been considered that sharks lost from one area would be compensated for with the movement and matings of sharks from other locations.
“Our findings suggest this is clearly unlikely and this, together with bycatch fishing, depletion of their food reserves, pollution, and poaching, could put this iconic apex predator in real danger of extinction.”