According to Taylor Chapple, a marine ecologist at the University of Oregon (United States), these animals they are fundamental to the marine ecosystem. For this reason, it is not only good news for white sharks, but also for the waters that wash the Californian coast.
White sharks are found in coastal waters around the world. However, according to the World Wildlife Fund, currently they are threatened by overfishing. Furthermore, its world population is in decline.
This team of researchers published a study of the shark population in northern and central California in 2011. Now, this new research updates the previous estimate with longer term observations. According to scientists, sharks usually spend half the year in the northeast Pacific, between Mexico and Hawaii. Then they spend the other half of the year closer to the coast, reaching as far north as Washington and as far south as Mexico.
Also, the largest populations of white sharks are found near Guadalupe Island (against Mexico) and in the current of California. This current runs from Monterey Bay (in the south) to Bodega Bay (north of San Francisco).
Likewise, from 2011 to 2018 the team of researchers has carried out observations from a boat at three different sites (Southeastern Farallón Island, New Year Island, and Tomales Point off the California coast). Thus, they were able to collect underwater images of great white sharks and more than 1,500 photographs.
To carry out the count the sharks looked at their dorsal fins. This is because, according to Chapple, Each white shark has a unique dorsal fin. In the words of the researcher “it is like a fingerprint with a barcode”. This individual identification also allowed the researchers to follow male and female sharks for a long period of time.