If you guessed the seabed, then you've got it right. Researchers reveal in a first-ever detailed study of a great white shark's diet that they spend most of their feeding time hunting for food just above the seabed.
According to Richard Grainger, the lead author of the study, they found a variety of fish species that typically live on the seafloor or beneath the sand inside the sharks' stomachs. Additionally, Grainger, a candidate at the Charles Perkins Centre and School of Life and Environmental Sciences at the University of Sydney, said that it was not what they expected at all.
The study examined the stomach contents of 40 adolescent white sharks, particularly of the species Carcharodon carcharias. Furthermore, the sharks were caught in the NSW Shark Meshing Program. The scientists used their data in comparison with published data, mainly from South Africa, to establish a nutritional scheme for the shark species.
The authors claim that their findings would be an essential contribution towards recognizing sharks' feeding and migratory habits. The study was published in the journal Frontiers on World Oceans Day on June 7, 2020.
Sharks as Bottom Feeders
According to Dr. Vic Peddemors, a co-author from the New South Wales Department of Primary Industries Fisheries, the team found that although mid-water fish, like eastern Australian salmon, were the prevalent prey for juvenile white sharks in NSW, their stomach contents also revealed that these sharks feed at or near the ocean floor.
Grainger added that their evidence correlated to data they gathered from tagging white sharks. Moreover, it did show them spending a lot of time, many meters below the surface.
Dr. Gabriel Machovsky-Capuska, an adjunct Senior Research Fellow at the Charles Perkins Centre and a co-author of the study, explains that understanding these predators' nutritional goals and how these relate to migration patterns will give a more in-depth understanding into what stimulates human-shark conflict. Moreover, it could also help us learn how to protect the species best.
Diet of a Great White Shark
The study found that based on affluence, the sharks' diet was mostly comprised of 32.2 percent of pelagic or mid-water ocean fish, such as Australian salmon, 17.4 percent of bottom-dwelling fish like stargazers, 14.9 percent of batoid fish such as stingrays, and five percent of reef fish, like eastern blue gropers.
According to Grainger, the remainder of the diet was unidentified fish or insufficient prey. He adds that underwater mammals, other sharks, squid, and cuttlefish were eaten less frequently by sharks.
Furthermore, the scientists also found that larger sharks were most likely to have a diet that was higher in fat. Experts think it is expected because of their high energy needs for migration.
Professor David Raubenheimer, the Chair of Nutritional Ecology in the School of Life and Environmental Sciences, says that the findings complement other research they've done. Evidence suggests that wild animals select their diets squarely to meet their nutritional needs.
Peddemors says that the findings of their research would provide a lot of information in assisting the process of protecting sharks and managing safe interactions they have with humans.
