Before engaging in any sort of strenuous activity the last thing a person would want to do is stuff themselves with fatty food; you don't see a lot of people pigging out at an all-you-can-eat fried chicken place right before they run a marathon. A new study of the migration patterns of great white sharks shows that this is exactly how they behave before a trip, according to Wired.
Researchers found that before making migrations that cover distances as far as 4,000 kilometers that sharks will gorge themselves on as many young, fat seals as they can. While on migration the sharks depend on the high-energy fat to fuel them while traveling in the open ocean. Researchers studied satellite data from tagged sharks to learn how quickly they burn off all of their stored fat, according to Wired.
Gen Del Raye, one of the authors of the report, spoke to Discovery News about the shark's ability to eat massive amounts of food in order to prepare for a journey.
"We know from researchers observing white sharks feeding on whale carcasses that one shark can eat more than 30 kg (66 pounds) of blubber in a single feeding," Del Raye said. "This has been estimated to be sufficient energy to allow a shark to survive for 1.5 months. One of my co-authors, Salvador Jorgenson, for example, has identified the same shark feeding on three juvenile elephant seals in the course of one week."
Sharks rely on stored fat in their liver to avoid sinking to the bottom of the ocean; sharks don't have gas bladders like fish. Researchers were able to study how quickly they burned off the fat in their liver by measuring the rate at which they would drift to the bottom of the ocean. They learned that as the shark's journey wore on the rate of sinking would increase, according to Wired.
"I'm hoping that these kinds of creative adaptations of the data we have will be able to tell us more about the physiological adaptations that allow sharks to undergo these migrations, and what role it plays in their life history," Del Raye told Wired.
No one is really sure why exactly sharks go on their epically long trips; it could be for mating or foraging purposes. One thing that they have observed is that when they reach the end of a trip they tend to return to the same places to stuff themselves full of seals, according to Discovery News.
"One shark, for example, has been observed to return to the same northern elephant seal rookery every year for 26 years," Del Raye said. "So it is clear that the sharks are relying on a dependable food source at the end of their journey."
