Two sand sharks had been noticed off Jones Beach by lifeguards and New York State Police drones round 8:30 a.m.
The sharks had been feeding on bunker fish.
The seaside reopened to swimmers a number of hours later.
Three thresher sharks had been noticed off Area 5 at Robert Moses Seaside round 10 a.m.
Swimmers had been allowed again within the water there round 12:30 p.m.