In the last several years, scientists studying great whites in False Bay, South Africa, have confirmed that this apex predator switches his feeding patterns from deeper waters around Seal Island to locales closer to shore as summer approaches.
“It has become generally accepted that white sharks are common close to the shore over the summer periods in Cape Town,” Alison Kock, shark researcher, told Clifton Shark Files recently.
The theory only crystallized in the last four years as scientists analyzed recent research data and studied older fisher records.
According to Thomas Peschak, author of South Africa’s Great White Shark, he noticed this trend when “my friend and white shark biologist Michael Scholl discovered (in 2003) large numbers of great white sharks in extremely shallow water (less than 2m deep) very close to some of South Africa’s bathing beaches, we initiated a research project to establish what brings so many sharks so close to shore.”
Peschak believes that white sharks come inshore in big numbers to socially interact with others of their species, perhaps even to mate or give birth to their young.
“We have observed many sharks interacting with one another at close range, following behind or swimming tight circles around one another for extended periods of time.”
During his research, he snapped one of the most famous shark photographs of the 21st Century showing a huge great white tracking a researcher in a yellow kayak.
Many mistakenly believed it was a hoax, which it was not.
The Mean Season of 1976
Clifton Shark Files, an online project dedicated to uncovering new insights into great white behavior in 1976, suggest that the seasonal shift theory may offer a partial explanation as to why a blue pointer may have swum into Fourth Beach, Clifton in November of that year.
On that day Geoffrey Kirkham Spence was bitten by a great white after he imitated a scene from the movie ‘Jaws’ he seen the day before.
His violent thrashings in water were picked up by a nearby great white, interpreting these strong vibrations as prey.
Spence would luckily survive the encounter.
Generally, it was thought then, and by many Capetonians today, that great whites did not like the freezing cold water of the Atlantic zone between Table Bay and Llandudno.
Instead, they gravitated towards the warmer waters of False Bay with its abundant seal colonies.
In November 1976, the Cape Town press published several alarming stories of great whites attacking ski boats in the False Bay.
The reports suggested that this aggressive behavior could be due to a suspension of sealing operations – the first in 10 years – that was initiated earlier that year.
Since disposed seal carcasses were no longer being thrown back into the water great whites had lost a reliable, consistent food source.
Great whites, according to the theory, were thus starving and turning ‘mean.’
An attack, suggested the press, was imminent.
However, when a bite finally took place, it was on the wrong side of Table Mountain, at Clifton, in cold water.
The 1976 great white shark bite thus offers an interesting lens in which to explore great white behavior and examine the seasonal shift theory.
Curiously, the water at Clifton on the day of the attack was close to 18-degrees Celsius, which is unusual for this sector of the Atlantic Ocean.
Many non-scientists have suggested that this may be a contributory cause for drawing a great white closer into shore. However, scientists are not so sure, saying the data is not conclusive.
The Clifton Shark Files confirmed that this bite bore uncanny similarities to another attack that took place in 1942 in virtually the same conditions.
In this incident the swimmer was dragged out to sea and never seen again by great white estimated to be over five meters in length.
The seasonal shift theory was not yet known in 1976 but it appears some fisherman and local Capetonians may have intuitively discovered it.
Shortly after the great white incident at Clifton a local resident made an insightful comment to The Cape Times newspaper.
“In his view, the sharks followed periodic warm currents into Table Bay. When these disappeared, taking the fish with them, the sharks began to forage for food close inshore. The temperature at Clifton at the time of the latest attack was 18 C,” said the Cape Times Report.
Over 40 years later shark researchers are still not entirely sure how many great whites swim in the Atlantic zone between Table Bay and Llandudno.
The seasonal shift theory, however, may offer some clues as to why there is an increase in shark attacks over the summer season in Cape Town.