South Africa is known for one of the world’s largest populations of great white sharks (Carcharodon carcharias). However, areas off the coast of the Western Cape province where sharks usually congregate have seen a significant decline. Researchers documented a peak of more than 300 white shark sightings at eight beaches in Cape Town in 2011, but have not recorded any sightings since 2019. This decline has raised concerns about the overall conservation status of this species.

Conservation of great white sharks is vital because they play an important role in marine ecosystems. As top predators, they help maintain the health and balance of marine food webs. Their presence influences the behavior of other marine animals, affecting the structure and stability of the entire ecosystem.

It was important for marine biologists to know whether the decline in shark numbers in the Western Cape signaled changes in the South African population as a whole, or whether sharks were moving elsewhere.

To investigate this issue, scientists conducted a large-scale study using data collected by tour operators and coastal fishermen. They examined trends in the abundance and distribution of sharks in Southern Africa over time.

The study found significant variation in abundance in primary collection areas. There were declines in some places; others showed increases or stability. An overall stable trend emerges. This shows that white shark numbers have remained unchanged since 1991. Scientists examining potential changes in shark distribution between locations found a shift in human-shark interactions from the Western Cape to the Eastern Cape.

“A stable population of white sharks is reassuring, but changing distribution creates its own problems, such as risks to fishing and the need for beach management. Better tracking of sharks’ whereabouts is therefore needed,” marine biologists say

“We recorded the biggest changes between 2015 and 2020. For example, shark sightings at Seal Island, False Bay (Western Cape) dropped from 2.5 sightings per hour in 2005 to 0.6 in 2017. To the east, to Algoa Bay “Only six sharks were caught by coastal fishermen in 2013. By 2019, that number had risen to 59. But the changes in each region are complex. Patterns remain difficult to understand.”

Scientists say white sharks can live more than 70 years. Each life stage is accompanied by distinctive behaviors: young people, especially males, tend to stay closer to the coastline, while juveniles and adults, especially females, venture out to sea.

Environmental factors such as water temperature, moon phase, season and food availability further influence their movements.

Changes in climate and oceans over long periods of time may also play a role.

As adaptive predators, they target a variety of prey and thrive in a wide temperature range, preferring temperatures between 14 and 24 degrees Celsius. Their migratory nature allows them to seek optimal conditions when faced with adverse environments.

Killer whales, who love shark liver, increase the difficulty of the move. Recently, scientists observed how these apex predators prey on white, sevengill and bronze whale sharks.

The cases were first documented off the coast of South Africa in 2015 and coincided with significant changes in the behavior of great white sharks in Gansbaai and False Bay.

Researchers believe that killer whales preying on sharks may be the cause of the migration of a large population of great white sharks. Finding a new place to live for the second
It can cause problems for both the sharks and the people living there.

While shark bites remain low, changes in shark movements can also impact beach safety. The presence of sharks can affect human activities, especially in areas popular for swimming and water sports. Current shark management strategies may need to be adjusted as their distributions change.

In Cape Town, for example, shark watchers concentrated their efforts on specific beaches. Following two shark deaths in 2022, their program was expanded to include Plettenberg Bay. Surfers and divers in the Eastern Cape are also encountering great white sharks more frequently than before. Scientists state that more research is needed to understand the factors behind shark movements. They are proposing long-term monitoring programs across the Eastern Cape and continuing work to reduce shark deaths. Source