The cruise boom in Tasmania has sparked growing concerns that the Apple Isle is being overrun by visitors.

With a record 21 cruise ships disgorging 35,000 passengers to Port Arthur last year, local government authority is considering staggering the number of ships calling at the historic site.

“It’s like a sort of invasion,” said Sharon Sullivan of the Port Arthur Historic Site Management Authority.

“You could have 500 people at a site and, if they all go to the same place at once, you can have a lot of impact whereas, if you spread people and if you sequence your activities, then you’ll have a much better outcome,’’ she said.

A total of 95 cruise ships will visit Tasmania this year – a 68 per cent increase on last year’s 59 ships. Most ships will call at Hobart, Port Arthur and Burnie. On Tuesday (December 5), Hobart had more than 7300 visitors spilling onto the city streets when Ovation of the Seas carrying more than 4100 passengers and 1300 crew and Pacific Eden with 1260 passengers and 580 crew visited the port.

“Certainly across the state, industry communities and government are watching very closely the dramatic increase in cruise ship visitation, not only in our established ports but also especially in sensitive areas,’’ Will Hodgman, Premier and Minister for Tourism and Heritage told the local newspaper, Mercury.

The World Heritage listed Port Arthur site is the best preserved convict precinct in Australia and commemorates the 1996 massacre in which 35 people were killed and 23 wounded. Today, the 19th century penal settlement is an open-air museum.

The growing popularity of Tasmania as a cruising destination has also raised concerns whether the influx of tourists will further tax infrastructure at hot tourist spots such as Cradle Mountain.

Tasmania is not the only state considering limiting the number of cruise ships calling at its ports. Overcrowding by cruise ships has also prompted Venice to ban giant holiday vessels from its historic site this year. Cruise ships of more than 100,000 tonnes will now have to take the less glamorous route to the industrial port of Marghera, far from the Grand Canal.

In Dubrovnik, another city where cruise ships unload thousands of visitors at a time, the mayor has introduced cameras to monitor the number of visitors in its UNESCO-listed old town, so that the flow of people entering can be slowed – or even stopped – once a certain number is reached.