 With the establishment of the Galapagos National Park and the CDF in 1959 , a review of the status of the tortoise populations began . Only 11 of the 14 original populations remained and most of these were endangered if not already on the brink of extinction . The breeding and rearing program for giant tortoises began in response to the condition of the population on Pinzón , where fewer than 200 old adults were found . All of the hatchlings had been killed by introduced black rats , for perhaps more than a century . Without help , this population would eventually disappear . The only thing saving it was the longevity of the tortoise . 
