Green anacondas can reach lengths of 29 feet. (Getty)
Green anacondas can reach lengths of 29 feet. (Getty)

A reptile specialist says that he was made to keep quiet by local officials about a 16 feet long anaconda on the loose in New Jersey's biggest freshwater lake.

There have been numerous local sightings of the serpent in Lake Hopatong, with most believing it was a boa constrictor that had escaped captivity.

Gerald Andrejcak, who was one of the team charged with recapturing the snake, says that he was made to swear that he would not reveal it was really a green anaconda, which are non-venemous but are more aggressive hunters than reclusive boas.

'I've known its species (since last week), but I was sworn to keep my mouth shut by local officials to avoid causing a panic,' he told NJ.com.

Now that there's a panic, I'm going on the record.'

He said that he saw the snake in a boat house on Thursday, but it slid into the water and evaded capture.

Andrejcak, who has a degree in zoology and more than 20 years experience handling and breeding large snakes, said he began following the snake sightings via news reports and Facebook.

After seeing it, he informed Hopatcong animal control officer Dale Sloat of its real identity.

"This big a snake would be aggressive," he told CBS.

Locals expressed their horror at the news.

'There's kids swimming in the lake, there's going to be people in the water this weekend, and my kids can't go in their backyard,' Tony Colantonio, who rents a property on the lake and says he has seen it, told NJ.com.

'It's a green anaconda, a predator, hunting all day every day. It's not a python that lives 80 percent of its life on land and only needs to eat once a month. It's one of the most aggressive snakes out there.

'It's been two weeks and (the township and state) have done nothing. Everybody I call just blows me off.'
Green anacondas can grow up to 29 feet in length, and can weigh up to 550 pounds.

Andrejcak said that it had probably been a pet, which was dumped in the lake when it became too large to care for.