Colombian officials on Monday authorized a plan to cull dozens of hippos roaming freely through a region in the center of the country, where they threaten villagers and displace native species years after notorious drug lord Pablo Escobar brought in the first ones.

Environment Minister Irene Vélez said previous methods to control the population of the so-called "cocaine hippos" have been expensive and unsuccessful, including neutering some of the animals or moving them to zoos. Vélez said up to 80 hippos would be affected by the measure. She did not say when hunting would begin.

"If we don't do this we will not be able to control the population," Vélez said. "We have to take this action to preserve our ecosystems."

Colombia is the only country outside of Africa with a wild hippo population. The hippos are the descendants of four brought to the country in the 1980s by Escobar as he built a private zoo in Hacienda Nápoles, a gigantic ranch in the Magdalena River valley with a private landing strip that served as his rural abode.

A study published by Colombia's National University estimated that around 170 hippos were roaming freely in the country in 2022.

Colombia has declared them an invasive species and experts have said sterilization alone is not enough to control the growth of the animals, which is why the government previously arranged for the possible transfer of hippos to overseas sanctuaries. But the cost of deporting the hippos is also expensive — an estimated $3.5 million.

Recently, hippos have been spotted in areas that are more than 60 miles north of the ranch.

Environmental authorities in Colombia say the mammals pose a threat to villagers who have encountered them in farms and rivers. They also compete for food and space against local species such as river manatees.

Independent journalist Audrey Huse, who has lived in Colombia for years, previously told CBS News that because the hippos roam freely, they end up killing fish and threatening endemic species like manatees, otters and turtles.

"Because they have no natural predators here, as they would in Africa, the population is booming an it's affecting the local ecosystem," Huse said. "Because they are such large animals, they consume considerable amounts of grassland and produce significant waste, which then poisons the rivers."

Despite the challenges, the hippos have also become a tourist attraction, with residents of villages surrounding Hacienda Nápoles offering hippo spotting tours and selling hippo-themed souvenirs.

The hippos are also one of the main attractions at the Nápoles ranch, which was confiscated by Colombia's government as it seized Escobar's properties. It now functions as a theme park, featuring swimming spools, water slides and a zoo that includes several other African species.

Last October, Colombian President Gustavo Petro announced the country handed over a chunk of Escobar's ranch to women caught up in the nation's armed conflict.

Animal welfare activists in Colombia have long opposed proposals to kill the hippos, arguing they deserve to live. They say that addressing the problem through violence sets a poor example for a country that has gone through decades of internal conflict.

Andrea Padilla, a senator and animal rights activist who helped draft a law against bullfights in Colombia, described the plan to cull the hippos as a "cruel" decision, and accused government officials of trying to take the easy way out.

"Killings and massacres will never be acceptable," Padilla wrote on X. "These are healthy creatures who are victims of the negligence" of government entities.

Over the past 12 years, spanning three presidential administrations, Colombia has tried to neuter some of the hippos in a bid to reduce their population. But the initiatives have had limited scope due to high costs that come with capturing the dangerous animals and performing surgeries on them.

Because Colombia's hippos come from a limited gene pool and could carry diseases, taking them back to their natural habitat in Africa has been considered unfeasible.