Giant turtles (tortoises are terrestrial turtles) are synonymous with the Galapagos Islands. The islands' name is derived from a Spanish word for saddle reminiscent of the carapace shape of one of the races. Of the fifteen races unique to each island, four are extinct. Its likely that the only giant turtles a visitor sees are captive ones at Darwin Research Station. These are part of an on-going breeding program to replace the wild turtles that have disappeared from islands like Espanola. To see wild turtles, you either must be very lucky or trek to the interior of the big islands, Santa Clara or Isabela. Turtles were once numerous, but predation by humans and invasive herbivores such as goats have reduced their numbers drastically. The Ecuadorian government has made extraordinary efforts to eradicate the feral goat. It is a voracious eater that can survive in extremely rough terrain. Goats can compete more successfully than cold blooded reptiles. Flanks of the shield volcanoes that form Isabela have been denuded of vegetation by the mammal. The extermination program has cost Ecuador $20 million and has achieved some success. The last goat on Santa Fe was killed in the 1990s. Vegetation has recovered and the island's endemic land iguana is thriving. Goats were finally exterminated from the northern half of Isabela in 2005. As many as 100,000 were shot and their carcasses left to decompose. In this drastic way the island's nutrients were returned to the soil for use by indigenous species. 
Six hundred or more invasive plant species have been introduced to the islands. Eight introduced mammals ranging in size from cows and pigs to cats and mice now inhabit the islands and are competing very successfully against endemic species. Thirty years were required to eradicate the feral pig from Santiago island. I was an eye witness to the problem of invasive insects. Our yatch and another sailing behind us encountered a swarm of paper wasps at sea between the islands of Floreana and Isabela. Several of the passengers enjoyed killing as many as they could with their flip flops. The guide found the event disturbing enough to report it to park authorities. When we landed on Isabela, the paper wasps were there too. The native pollinator is the carpenter bee--a large, slow flying and solitary bee. An organized colony of wasps could probably make short work of the native. Darwin finches, "a most singular group of finches" according to the great naturalist, are also experiencing a vicious assault by an introduced insect. Flies, probably brought in with food supplies from the mainland, are laying their eggs in finch nests. When hatched, the maggots feed on the finch chicks. The mangrove finch, the rarest, is particularly hard hit. Scientists estimate that the species is down to 50 pairs of birds on the northeast coast of Isabela. The finches are a living example of adaptive radiation. To loose even one finch species because of man's modern impact on the islands would be a tragedy.
Human habitation of the Galapagos is a 500 year old fact. No one is suggesting putting the islands off limits to humans even if that were feasible. What is needed to be establish are strict control of the number of visitors to the National Park each year and limits on the total population of residents. Better enforcement of marine reserve regulations are also needed. Visitor sites that are suffering adversely from tourist use should be closed and allowed to recover. I was told that the large amount of money contributed each year to the private Darwin Foundation is not shared with the National Park for it's protection or
enhancement. If this statement reflects the current situation, the Foundation should consider helping the Ecuadorian government with contributions. The direct link between tourist revenue and park expenditures needs to be broken. Another criticism expressed was that scientific studies are often esoteric and of little practical value. The impacts of tourism on the Galapagos and it's wildlife should be closely studied and the results shared with responsible government officials. If international cooperation to protect the Galapagos is not increased to deal with the relatively new environmental dynamic of mass tourism, the isles will be enchanting no longer.