The World Wildlife Fund recently publicized a Congolese Institute for the Conservation of Nature survey of the hippopotamus population in the Democratic Republic of Congo. That survey estimates that the hippo population has declined from a high of 29,000 in the early 1970s to only about 1,300 specimens today.
Of course the Democratic Republic of Congo has been racked by war and corrupt governance during much of that period, so it is hardly surprising that poachers and others have been killing hippos with impunity. What is genuinely surprising is the perverse effect that the ban on the trade in ivory has had on hippo populations. According to New Scientist,
In recent years, hippo meat has become a delicacy in parts of central Africa. Furthermore, the present worldwide ban on the trade in elephant ivory has meant hippo teeth, which can grow to 60 centimeters or more long, have become a valuable substitute.
This switch is darkly ironic, because hippos are now much rarer than African elephants. The global hippo population is now estimated at about 150,000, but there are more than half a million African elephants.
African nations where elephants are plentiful have repeatedly petitioned for a resumption of the world ivory trade (limited lifting of the ban, usually to sell pre-ban ivory stocks, has taken place occasionally since 1989).
Sources:
Poaching causes hippo population crash. NewScientist.Com, August 29, 2003.
Poachers will wipe out hippos in Congo, WWF warns. Reuters, August 28, 2003.