Biology Loss of great white sharks damages marine ecosystem, study finds
The disappearance of great white sharks in a bay of the Atlantic Ocean off South Africa has had serious consequences for the marine ecosystem. This was reported by a research team in the journal "Frontiers in Marine Science".
30.03.2025, 06:41
SDA
The loss of top predators has had a negative impact on the entire food web, from seals to smaller shark species and fish.
Over a period of two decades, the group from the US University of Miami studied the role of the great white shark (Carcharodon carcharias) in False Bay in the Atlantic Ocean, which borders the tourist metropolis of Cape Town. The data is based on shark sightings by boat, observations of Cape fur seals by local residents and recordings from remote-controlled underwater cameras of fish and small sharks.
The study provides empirical evidence of the impact on marine biodiversity when white sharks are absent from the top of the food chain. "The loss of this iconic apex predator has led to an increase in sightings of Cape fur seals and sevengill sharks, which in turn has been accompanied by a decline in the species they rely on for food," said lead author Neil Hammerschlag. This in turn has led to a decline in fish that seals and smaller shark species feed on.
White sharks important for healthy oceans
The results confirm the long-established theory that the disappearance of a top predator has a cascading effect on the marine ecosystem, according to Hammerschlag. They demonstrated the important role of white sharks in maintaining the health of the oceans. "Without these apex predators regulating other populations, we see measurable changes that could have long-term effects on ocean health," Hammerschlag said.
According to the researchers, the False Bay region, where the great white shark was once very common, has seen a dramatic decline in the animals since 2015. The apex predator has not been sighted in the bay since August 2018. According to the study, the reasons for this include the nets set up in the sea to protect bathers, in which the sharks become entangled. On the other hand, deadly attacks by killer whales - or orcas - have probably driven the white sharks out of the bay.
