Central California is thought to support one of the largest populations of the great white shark in the world, yet as few as 219 great white sharks may exist in the waters there, according to a new study.
In what is likely to be the world’s first detailed count of great white sharks, scientists took advantage of the unique arrangement of notches, cuts and flat sections on the dorsal fin of the sharks to identify different individuals in the region. Similar to a human fingerprint, no two dorsal fins of the great white shark are alike.
The scientists were able to estimate the number of sharks in the area by using digital photography, information from a database and mathematical models.
The results found that numbers of the great white shark were much lower in Central California than was expected, prompting fears that this charismatic marine predator may be more endangered than previously thought.
Currently, great white sharks are considered to be ‘Vulnerable’, according to the IUCN Red List. However, if the kinds of counts found by the researchers in this study can be supported elsewhere, then the great white may be reclassified as ‘Endangered’, or even ‘Critically Endangered’, in the future.
Great white sharks, along with other sharks and many top marine predators, are threatened by overfishing and destructive fishing practices, such as shark finning. In addition, habitat loss and pollution are also contributing to global declines.
Sharks are large ‘apex’ predators, meaning that they are found at the top of the food chain. According to Taylor Chapple, lead author of the study, declining great white shark populations are likely to have “significant negative effects on the health and functioning of marine ecosystems. Even the loss of a single individual could have serious consequences.”
The decline of sharks in oceans worldwide underscores the need for careful assessment and monitoring of remaining populations of these captivating creatures.
Read more about the study in Biology Letters.
Find out more about the great white shark on ARKive.
Helen Roddis, ARKive Species Text Author