Study of Australian Great white sharks’ diet reveals fascinating feeding habits
FirstforNews reports on this captivating study, the first of its kind detailing the complex feeding habits of great white sharks off the eastern Australian coast.
The study found that the great white’s diet relied on comprised mostly of Pelagic, or mid-water ocean swimming fish, such as Australian salmon, comprising around 32.2% of their total diet, with fish usually confined to the ocean bed including flatheads, sole and stargazers comprising of 17.4%, rays, including stingrays and eagle rays accounted for 19.9% and reef fish, such as eels, mullet and the large blue groper accounted for 5%, with he remainder being unidentified fish species, cuttlefish and squid.
The study examined the stomach contents of around 40 young great white sharks, with researchers comparing the results with other dietary studies in South Africa, providing detailed data on what the sharks are eating.
The report was published the day after a great white attacked and killed a surfer off the northern New South Wales (NSW) beach, the attack being the third fatality from sharks in Australia this year.
“The stereotype of a shark’s dorsal fin above the surface as it hunts is probably not a very accurate picture”, said lead researcher Richard Grainger, from the Charles Perkins Centre, School of Life and Environmental Sciences at the University of Sydney.
“Within the sharks’ stomachs we found remains from a variety of fish species that typically live on the seafloor or buried in the sand. This indicates the sharks must spend a good portion of their time foraging just above the seabed”
Dr Vic Peddemors, a fellow contributor from the NSW Department of Primary Industries said: “We discovered that although mid-water fish, especially eastern Australian salmon, were the predominant prey for juvenile white sharks in NSW, stomach contents highlighted that these sharks also feed at or near the seabed.”
“Understanding the nutritional goals of these cryptic predators and how these relate to migration patterns will give insights into what drives human-shark conflict and how we can best protect this species,” said Dr Gabriel Machovsky-Capuska, an adjunct Senior Research Fellow at the Charles Perkins Centre and a co-author of the study.
“The hunting of bigger prey, including other sharks and marine mammals such as dolphin, is not likely to happen until the sharks reach about 2.2 meters in length” said Mr Grainger.
The scientists also found that larger sharks tended to have a diet that was higher in fat, likely due to their high energy needs for migration.
Co-author of the report, Professor David Raubenheimer, Chair of Nutritional Ecology in the School of Life and Environmental Sciences went on to conclude;
“This fits with a lot of other research we’ve done showing that wild animals, including predators, select diets precisely balanced to meet their nutrient needs”
Establishing diets and dietary generalism in marine top predators is critical for understanding their ecological roles and responses to environmental fluctuations. Nutrition plays a key mediatory role in species-environment interactions, yet descriptions of marine predators’ diets are usually limited to the combinations of prey species consumed.
Credit: “Diet Composition and Nutritional Niche Breadth Variability in Juvenile White Sharks (Carcharodon carcharias)” by Richard Grainger, Victor M. Peddemors, David Raubenheimer and Gabriel E. Machovsky-Capuska