should they stay, or should they go

I put this here because I figured it would end up here

http://news.nationalgeographic.com/2016/05/160510-pablo-escobar-hippos-colombia/

Pablo Escobar's Escaped Hippos Are Thriving in Colombia
Can the dangerous animals be stopped from taking over more territory?

1. invasive non-native and must be removed
2. dangerous and must be removed
3. Columbia's ecosystem is perfect and no further improvements are possible

or
4. they give Nature another tool to further evolution
5. they can provide the onetime non-native, invasive, but currently, indigenous humans another source of income