The Columbian government has begun sterilising Pablo Escobar's infamous 'cocaine hippos'.
Before the drug lord was shot and killed by police in 1993, he had illegally imported four hippos to join his personal zoo in the 80s.
The government took control of his illegal zoo after his death, but didn't do anything about the hippos.
Due to not having any natural predators in the area, the animals were able to multiply to a population of over 80.
The BBC reports that the Columbian government has now sterilised 24 of the illegally imported mammals.
Explaining why the hippos were allowed to continue to live in the area surrounding Escobar's former ranch Hacienda Nápoles, Colombian biologist Nataly Castelblanco told the publication: "It was logistically difficult to move them around, so the authorities just left them there, probably thinking the animals would die."
Instead the hippos rapidly multiplied. Castelblanco explained that while hippo populations are controlled by draughts in Africa, the climate in Colombia is ideal for them, meaning they start reproducing at an earlier age.
Many have been campaigning against the mammals, with calls for culling or sterilisation, as they are believed to be 'very dangerous'.
The urine and faeces produced by the animals is toxic and contains bacteria that is dangerous to both other creatures and humans.
Hippos also kill more people annually in their native Africa than any other mammal, and last year one of the 'cocaine hippos' flung a cattle farmer in the air, breaking his hip, leg and several ribs.
Ecologist Nataly Castelblanco-Martínez told The Telegraph earlier this year: "Nobody likes the idea of shooting a hippo, but we have to accept that no other strategy is going to work.
"Relocation might have been possible 30 years ago, when there were only four hippos.
"Castration could also have been effective if officials had provided sufficient resources for the programme early on, but a cull is now the only option."
However, others argue that sterilisation is a better approach.
Enrique Ordoñez, a biologist at Colombia's National University, told CNN that castration is the right way to go about it, as the 'cocaine hippos' might actually be of some good to preserve global hippo numbers.
They are considered a vulnerable species by NGOs such as the International Union for Conservation of Nature (IUCN).
He said: "Right now, the authorities don't consider the species to be a problem, but in the future, when there are 400-500 hippos, it could represent a threat to the survival of other species that feed in the same areas."
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