Del Raye, Jorgensen and their colleagues assessed great white shark fat stores over long periods by examining depth records from pop-up satellite tags affixed to sharks in the Eastern Pacific Ocean. Changes in shark buoyancy served as a proxy for how much weight the toothy predators were packing.
As a shark's single largest organ, the liver, can account for 28 percent of an adult's body weight. Other fat is stored in the shark's muscles. While sharks fill up on fatty food after long journeys, no shark has ever been classified as obese. Their lifestyle is probably inherently too active for them to keep the pounds on.
Great white sharks go on long distance migrations covering over approximately 2,485 miles per trip. It's not certain why they undertake such lengthy journeys, it's likely foraging, mating or both.
"Our study is another piece of mounting evidence that the major feeding point in the shark's yearly cycle occurs along the coast," Del Raye said. He added that they may go offshore to mate or move away from the California Current when their main prey, juvenile elephant seals, are not present. And they "may be avoiding the seasons with the coldest water temperatures near shore."