Besides his or her own relatives, the shark's biggest predator is man's appetite. Many sharks are endangered because they have been overfished. While they may be speedy feeders, they are slow to reproduce. It generally takes sharks about 10 to 20 years to mature. Large sharks eat only once every week or two, smaller sharks eat every day, according to Wilga, who notes that most sharks are picky eaters and don't hanker for humans.
Most sharks give birth in warm water during the late spring and early summer.