There are fears that 166 hippos that drug lord Pablo Escobar owned in the 1980s could become feral, so Colombia is planning to cull some of them in an effort to control their numbers.
Environment Minister Susannah Muhammad said that twenty people would be sterilized, some would be taken abroad and “some” would be killed.
Experts have been trying to control the hippopotamus population for years.
Escobar imported hippopotamuses for his Hacienda Napoles private zoo. When he was shot dead by the police in 1993, he was left to roam.
Authorities have tried a variety of strategies to reduce population growth in the Magdalena, Colombia’s largest river, including sterilization and transferring some species to neighboring zoos.
Despite best efforts, the herd continued to grow uncontrolled because the fertile, marshy Antioquia terrain and lack of predators provided the perfect environment for the native African mammal to thrive.
The demise of hippos was sealed last year when they were labeled as an invasive species, opening the door to genocide.
“We are working on protocols for exporting the animals,” local media quoted Muhammad as saying.
“We will not export a single animal if there is no permission from the environment authority of the other country.”
He said that as a last resort, the ministry is developing a policy for euthanasia.
Experts in Colombia have long warned that uncontrolled breeding of hippos threatens both indigenous animals and people.
If nothing is done, the population is projected to reach 1,000 by 2035. However, animal groups claim that sterilization causes pain to the animals and poses a serious risk to veterinarians.
Male hippos can weigh up to three tons as adults, making them one of the largest land mammals. They are one of the deadliest, killing about 500 people annually.
There have been attacks on fishing communities along the Magdalena River, and some hippos crossed into a school grounds, but no one has been killed.
Leading the Medellin Cartel, Escobar earned the nickname “Cocaine King” and amassed an estimated fortune of $30 billion (£25 billion) by transporting drugs across Miami and the southern United States.
During his more than ten-year reign of terror, he was involved in kidnappings, hundreds of murders, bombings, bribery, clashes with rival drug lords and a brief stint as an elected politician.
One of the most wanted men in the world, he surrendered to Colombian police in 1991 with the understanding that he would be held for five years in a prison called La Catedral, which he had built.
A year later, despite government efforts to transfer Escobar to a more secure prison, he escaped.
In his hometown of Rionegro, he was shot and killed on a rooftop while trying to escape from authorities on 2 December 1993, prompting a US$2 million bounty on his head.
In addition to leaving behind a 5,500-acre private fortress in Antioquia, called Hacienda Napoles, he also left a history of violence and a zoo that included four hippos, giraffes, camels and zebras.
After Escobar’s death, the government turned the property over to the poor residents, and the hippos were allowed to roam freely because it was believed that they were too difficult to capture.