A new study has highlighted the importance of sharks, especially large species, by showing how the disappearance of Great White Sharks (Carcharodon carcharias) from a part of South Africa led to a cascading effect in the marine food chain.
The study, conducted by scientists from the University of Miami Rosenstiel School of Marine, Atmospheric and Earth Science, spanned over two decades.
The researchers used a combination of long-term boat-based surveys of shark sightings, citizen science observations on Cape fur seals, and Baited Remote Underwater Video Surveys (BRUVS) of fishes and small sharks to show the downside of not having an apex marine predator.
Great White Sharks disappeared from False Bay in South Africa, where they were once abundant with potential causes being decades of unsustainable captures in nets intended to protect bathers and some recent instances of predation by Orcas, according to a statement by the Rosenstiel School of Marine, Atmospheric and Earth Science.
The absence of the sharks led to an increase in Cape fur seals (Arctocephalus pusillus) and sevengill sharks (Notorynchus cepedianus) and an associated decline in fish that the seals feed on and smaller shark species that the sevengills prey on. This, according to the study, illustrates the ripple effect of losing an ocean top predator.
According to the scientists, the study is proof of what can go wrong when in marine ecosystems when sharks such as Great Whites disappear.
“The findings emphasize the importance of global shark conservation efforts, as their loss could have long term consequences on marine ecosystems. Given the global reliance on healthy oceans for food, recreation, and ecosystem services, protecting large sharks is essential to maintaining biodiversity,” the statement noted.
The study, titled “Evidence of cascading ecosystem effects following the loss of white sharks from False Bay, South Africa” was published on March 25, 2025 as an open-access paper in Frontiers in Marine Science. The authors include Neil Hammerschlag and Yakira Herskowitz from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Chris Fallows from Apex Shark Expeditions, and Thiago B.A. Couto, from Lancaster Environment Centre, Lancaster University.