West Africans get their protein mostly from fish and bushmeat. When they can’t get enough fish they eat more wild animals. Heavily subsidized European fishing vessels caught twenty times more fish in the Gulf of Guinea in 2001 than in 1950. Domestic fishing increased as well. As a result, fish stocks have declined by half since 1977 and per capita fish supplies have also fallen. That has led to more hunting. If something is not done soon, the fish and wildlife populations will both collapse, people will lose their sources of protein, and species may go extinct.

That is the sobering message of Justin Brashares and his colleagues in “Bushmeat Hunting, Wildlife Declines, and Fish Supply in West Africa”, a recent piece in Science focusing on Ghana. The authors based their conclusions on thirty years of data on fish supply and the biomass of 41 species of mammals, sixteen years of records on the number of hunters encountered by wildlife rangers in five nature reserves, and five years of monthly data on the volume and prices of fish and wildlife sold in 12 local markets in north, central, and eastern Ghana. They found that when less fish was available, fish prices and the number of hunters and volume of bushmeat sold all rose significantly, while wildlife populations declined; and the effects were stronger in places closer to the sea.

The good news is that people were able to use bushmeat as a safety net. When they didn’t have fish they could still eat meat. The bad news is they clearly can’t keep doing that forever. Hunting caused the population of the 41 monitored species to decline 76% between 1970 and 1998 in the five reserves and some species disappeared from the reserves entirely.

To address the problem, the authors suggest that European governments stop subsidizing fishing in African waters and Africans take steps to reduce over-fishing, particularly by foreign vessels. They would also like to see more and better-protected wildlife reserves, to build up the animal populations for people to hunt. Eventually, crops and livestock might provide alternative sources of protein. But time is running out.