Hippos descended from pets of Pablo Escobar keep multiplying. Colombia has started to sterilize them.

Colombia on Tuesday began the sterilization of hippopotamuses, descendants of animals illegally brought to the country by late drug kingpin Pablo Escobar in the 1980s.

Two male hippos and one female underwent surgical sterilization, environmental authorities said. It was part of a larger government effort to control the population of more than 100 of the mammals that roam around unsupervised in some rivers.

The plan includes sterilizing 40 hippos each year, transferring some of them to other countries and, possibly, euthanasia.