Town of Hempstead lifeguard patrolling the waters for sharks at...

Town of Hempstead lifeguard patrolling the waters for sharks at Lido Beach West in Lido Beach on Wednesday. Credit: Newsday/J. Conrad Williams Jr.

Sharks swimming too close to Long Island beaches temporarily halted swimming at Robert Moses State Park, delayed the opening of nearby Jones Beach State Park, and led Hempstead to limit swimmers to knee-deep only, officials said Thursday.

Swimmers were allowed to return to the Atlantic at Robert Moses State Park in Babylon just before 12:30 p.m. and Jones Beach in Wantagh shortly before 11 a.m. Thursday, said George Gorman, the Long Island regional director of the Office of State Parks, Recreation and Historic Preservation.

The two state parks are about 11 miles apart, and ever since last week, a spate of shark sightings has led state and county police, state park police and lifeguards and local officials to say they have increased their vigilance, adding patrols by land, sea and air.

The sand sharks, which were about 700 feet from the beach in front of the Central Mall at Jones Beach in Wantagh on Thursday, were seen by lifeguards before the park opened for swimming at 9 a.m. and confirmed by drones flown by a lifeguard and State Police, Gorman said.

Shark sightings are becoming more routine, as Long Island's waters revive from decades of pollution, though both the Great South Bay and the Long Island Sound still have areas where oxygen levels have been sorely depleted, scientists say.

On Wednesday, Hempstead limited swimming to waist-deep and wading to knee-deep after two blacktip sharks, much more commonly seen in warmer, southern waters, were spotted about 20 yards offshore, officials said.

That same day, Nickerson Beach in Lido Beach also was closed and in Long Beach, swimming was barred for about 90 minutes after a shark was seen near Pacific Boulevard.

From threshers to great whites, here are some of the sharks you might find off LI. Credit: Gabriella Vukelic / Newsday

"We continue our enhanced monitoring of the beachfronts so that we can ensure public safety," Gorman said.

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