The town's shark patrol said they spotted a significant number of cow-nosed rays in the waters, which are known to be a favorite feeding choice for sharks.
A total of 13 shark sightings since Monday have halted swimming at beaches on Long Island.
Two sightings were reported Saturday.
Lifeguards were forced put out red flags and clear the water at Lido Beach on Saturday afternoon after seeing a large dark fin emerge from the water, seemingly going after prey.
Hempstead Town Supervisor Don Clavin said the fin was spotted and a large splash was noticed. Some patrons in the water also noticed and began to run out of the water.
"The lifeguards immediately responded by 'red flagging' the waters and getting everyone out of the water," he said. "As of this time, our lifeguards are taking the precaution of prohibiting all swimming at Hempstead Town beaches until further notice."
A few hours later people were allowed to return to the water, but only up to their knees.
However, another sighting happened around 4 p.m. as all swimming at Hempstead Town beaches are closed until further notice.
*Beach Update (August 1st — 4:15pm)*— Town of Hempstead (@HempsteadTown) August 1, 2020
Due to a shark sighting by Nassau County Police, all swimming is now prohibited at Town of Hempstead ocean beaches from Civic Beach to Lido West beach until further notice.
The shark sighting was reported by neighboring city of Long Beach. The town ended up closing for the rest of the day in coordination with Long Beach.
Lido Beach was knee deep for most of Saturday due to the 1 p.m. shark sighting.
Lifeguards are also advising beachgoers to be aware for the potential of strong riptides as a result of Tropical Storm Isaias making its way up the Atlantic coast.
On Friday, a Town of Hempstead lifeguard with the newly formed Shark Patrol spotted the shark off Lido Beach just before 4 p.m., halting swimming at all Town of Hempstead ocean beaches from Civic Beach to Town Park Lido West beach.
The Shark Patrol consists of Jet Ski watercraft and the deployment of a team of lifeguards on a Bay Constable boat to monitor the waters as needed during this period of shark sightings. Nassau County also has enhanced helicopter patrols and intensified marine ocean patrols.
There were three sightings each day on Monday, Tuesday and Wednesday, along with one Thursday and the most recent one Friday.
"It's not yet known if these sightings are the same shark, or different sharks," Nassau County Executive Laura Curran said.
Meantime, TJ Minutillo, 21, of Manhasset, showed up to the press conference and shared his amazing story of reeling in a bull shark at Nickerson Beach in Nassau County.
He said he caught the shark using a Sea Robin Fly and hooked it right after sunset on Saturday, July 18. Then, he engaged in a two and a half hours long battle with the 8-foot-long beast, before reeling it in with the help of his friends.
"I've been doing a lot of land based shark fishing for five or six years," Minutillo said. "We hooked a bull shark and not a sandbar or sand tiger."
After posing for a series of photos, with both of the shark and Minutillo exhausted, he took the hook out with a pair of pliers and let it go.
"I didn't know the regulations on it," he said. "It wouldn't have been worth it to me, so I threw it back, catch and release, it's sport fishing."
The shark was confirmed by environmentalists to be a bull shark which they estimate weighed 300-400 pounds.
"I Think it's wonderful that you let it go, it was the kind thing to do," Curran said to Minutillo.
After he was done speaking, Curran posed for a photo with Minutillo.
Watch: Lifeguard describes shark sighting
"It's a very difficult time down here," Town of Hempstead Supervisor Don Clavin said. "It's a combination of factors, as I stressed to everybody. We have a pandemic, we have a 50% capacity at the beaches, we have the hottest days of the summer, and we have had shark sightings that are clear cut."
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On Saturday, one beachgoer took a video of an apparent shark in Hampton Bays.
Nassau County Police Commissioner Patrick Ryder said it's possible that sharks may not be out at the exact point when they are looking, so swimmers should always listen to the lifeguards.
"The lifeguards between the Town of Hempstead, the county, and the state are experts at what they do," he said. "They are professionals. If they tell get out of the water, get out of the water, don't hesitate."
"I just want residents to know a bull shark is an incredibly dangerous creature," Clavin said. "People always hear about the great white sharks, well a bull shark is even more dangerous really to the swimmers in the South Shore. Why? These predators like to go to the shallower areas. They like to be closer to the coastline, where the swimmers are."
He added, "We want you to enjoy yourselves. We know this is a very hot period, but we want you to be safe...and if we see or hear of any other sightings, we will take the precautions necessary."
The Tuesday sightings came one day after three shark sightings Monday afternoon, with the first being a Town of Hempstead lifeguard who reported seeing a significant sized shark near a lifeguard on a surfboard.
They weren't sure of the exact size, but the shark was just eight to 10 feet away from the shore.
Authorities released a photo of a sea ray that washed up with enormous bite marks.
"By the shape of the head, shape of dorsal fin, fitness of the body, we determined it as a bull shark," Chief Town Lifeguard Mike Romano said.
The water temperature is now close to 80 degrees, and experts believe sharks are moving closer to shore in search of food.
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There have been at least 26 shark sightings in New York in the past 12 months.
With more people boating during the pandemic, the thinking is that's why there's been more reported sightings, while the actual number of sharks in the water is likely similar to previous years.
Fortunately, no one was injured by the sharks in the New York area.
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