Think of great white sharks, and many of us think of South Africa. With endless nature documentaries being filmed out of the nation’s bays showing the sleek predators ambushing and breaching on fur seals, you would be forgiven for thinking that this little patch of the ocean is a haven for the creatures. But it seems not so.
Over six years, a team of researchers from Stellenbosch University have tracked many of the sharks that live in the region using biopsies and dorsal fin recognition in the largest study of its kind in South Africa. They have concluded that there are only between 350 and 520 great whites cruising the waters off the country’s coast. “The numbers in South Africa are extremely low,” says Sara Andreotti, the lead researcher of the study published in Marine Ecology Progress Series, in a statement.
The number they settled on is much lower than anyone had really considered. In fact, most thought that there were at least double the number the researchers found. The study places the blame for the sharp decline of the species on a number of causes, including trophy hunting, shark nets, ocean pollution, and baited hooks. All these factors have contributed to the species diminishing at an alarming rate, which is expected to have knock on effects to the marine ecosystem.
“The chances for their survival are even worse than what we previously thought,” continues Andreotti. “If the situation stays the same, South Africa's great white sharks are heading for possible extinction. We have come to the conclusion that South Africa's white sharks faced a rapid decline in the last generation and that their numbers might already be too low to ensure their survival.”
From this latest count, despite there being at least around 450 of the animals persisting, the researchers think that only around 333 of these are capable of breeding. This could be too small a population, the researchers warn, for the sharks to survive long term into the future, and this could have dire consequences.
The great whites are what is known as an "apex" predator, in that it sits at the very top of the food chain, keeping the numbers of many other species in check. For example, if there were no more sharks patrolling the waters off of South Africa, then the number of Cape fur seals would explode, potentially threatening the local fish stocks.
But the researchers do write that while things may not be looking great for those sharks living off the Cape of Africa, the numbers seen in other populations worldwide appear to be healthy, such as those off the coast in Australia, Canada, and the United States.