Majority of shark bites are a matter of mistake identity rather than predatory attacks. Studies have shown sharks to often confuse human silhouettes (surfers) with seals or sea lions.
Not all sharks must remain in constant motion, only sharks that rely of obligate ram ventilators must swim to survive, Nurse sharks, tiger sharks, and bull head sharks are all examples of shark species that use buccal pumping to breathe, allowing them to safely stay stationary.