Conservationists fear that forthcoming BBC programmes about the Galapagos islands will lead to a tourist boom that could damage the fragile ecosystem of the remote Ecuadorean islands.

From the end of the month, BBC Two is running three hour-long programmes on the Galapagos, while Equator, another BBC Two series, features the islands tomorrow. The current BBC Wildlife magazine features the Galapagos islands on its front cover, and Radio 4 is also planning coverage.

But the Galapagos Conservation Trust is worried that the islands will not be able to cope with more visitors. It says that the number of tourists has already more than doubled in the past decade from about 50,000 in 1996 to 120,000 last year.

The Trust believes that political instability in Ecuador has allowed tourism to grow too rapidly. This has led to the population on the islands doubling to about 30,000, most of whom are employed in the travel industry.

A spokeswoman said: “While the BBC’s new Galapagos series is going to help our cause, many of our gritty campaigns — on mass tourism, invasive species, shark finning — will be overlooked in favour of cute animals and amazing underwater footage.”

She added: “And will viewers say, ‘Now I want to go and see the Galapagos, aren’t they beautiful?’ Visitor numbers could rise even higher. People should be aware of the fragility of the ecosystem.”

The Galapagos — famously visited by Charles Darwin on the Beagle in 1835 — were the first place to be designated a World Heritage Site in 1978. They are home to thousands of rare species, including marine iguanas, giant tortoises, blue-footed boobys, sea cucumbers, flightless cormorants, woodpecker finches and Galapagos sea lions.

Felipe Cruz, technical director of the Charles Darwin Foundation, a conservation group based on Santa Cruz, one of the 13 main Galapagos islands, told Times Travel that the growing number of residents and tourists is putting a big strain on resources such as water and electricity.

He believes that the current visitor fee of $100 (£53), which goes towards conservation, should be increased to $500 (£267). This, he said, would limit numbers and help to tackle problems created by tourism.

“At the moment the Galapagos is extremely cheap,” he said. “People pay much more to visit places such as the Serengeti. We should increase our entry fees.”

He added: “The islands have limited resources. The more people we bring in the more strain there is on these. There is also the danger of introducing viruses such as avian flu or the West Nile virus.

“Earlier this year a cruise ship came with 500 people on board. Some locals welcomed this because of the money they spent. But the hardest part of our job is explaining that greater numbers will not, in the long run, bring greater economic benefits.”

Invasive species on the islands include cats and dogs brought in by local residents — some pets have been known to attack birds, tortoises and turtles. There is also an illegal fishing problem, with some fishermen supplying food for tourists.

Patrick Morris, series producer of the BBC Two Galapagos series, which begins on September 29, said that he is aware of the problems caused by mass tourism and that these issues will be addressed in an additional programme that will be shown on BBC Four on October 7.

He said: “It’s on the people of the Galapagos talking about the challenge of tourism, and about geological and climatic change. We discuss the new dangers of our growing presence on the islands.”

Details: Galapagos Conservation Trust (www.gct.org); Charles Darwin Foundation (www.darwinfoundation.org).