After a lot of research and testing, scientists have discovered that lipids stored in the shark's liver is what enables them to travel such a long distance without prey.
There are tons of different great white shark migrations around the world, and many of those migrations involve going through a long stretch of open waters, where prey is scarce for miles. Scavenger-like sharks would be inefficient, slow, and sometimes flat out not viable. This is the reason that sharks have a system in their body that allows them to survive for a long time without food. There is a specific route that many sharks take that starts in the coast of central California and it goes out all the way to seasonal food hot spots in the Pacific Ocean near Hawaii. These sharks travel through 2,500 miles of open ocean where food is scarce. Thanks to their special adaptation, these trips are possible.
The impact a shark's liver has on its physical state is staggering. A well fed shark's liver is made of of 90% of lipids and contributes to 25% of the shark's total body weight. In order to fill their livers for a long trip, sharks tend to target seals and whales. They choose these animals because they have lots of blubber, and blubber is rich in fat. Fat is a huge part of lipids and it is great for cell function and health.
So how can scientists tell when sharks have lots of lipids being stored in their bodies? The answer lies in their buoyancy. Sharks swim in two kinds of ways. They swim by using their own energy to propel themselves, and they also drift dive. Drift diving is when sharks use their own momentum and the underwater currents to propel themselves forward without having to use a lot of energy. This is an especially important tactic when travelling long distances with low reserves. Something interesting happens when sharks are drift diving. Depending on how many lipids they have in their liver, they will descend at a certain rate. Lipids are less dense than water, and because of this, sharks with more lipids in their body will descend at a slower rate than sharks that lack them. With mathematical formulas, scientists can accurately predict how many lipids sharks have in their livers at any given moment in time.
Unfortunately, we don't have the gift that sharks do. So remember, next time you go out for a long time, maybe on a hike or to go camping, bring lots of food and water, because you never know what can go wrong.