In West Africa, declining fish harvests have led to upswings in the hunting of wild animals for food, further endangering already rare species in the region. A study published in today's issue of Science is the first to show a statistical connection between smaller fish harvests off the coast of Ghana and increased hunting in that country's nature reserves. The authors suggest that efforts to protect wild animals on land can't afford to ignore larger economic issues--for example, the heavily subsidized foreign fleets that fish the deep waters off the West African coast.
Hunting and eating wild game, or bushmeat, is a major issue for conservationists in developing countries. In many areas, increased numbers of hunters--and increased firepower--have driven species that have long been consumed for food by traditional societies to the brink of extinction. Industrial logging, which opens up remote forests to hunters, has been blamed as one of the biggest culprits, but in recent years some have argued that falling fish harvests in coastal areas might also play a role.
Justin Brashares, a bushmeat expert at the University of California, Berkeley, and his colleagues studied records of Ghanaian fish harvests from 1970 to 1998 and compared them with estimates of the biomass (the number of animals observed multiplied by the species' body weight) for 41 wild animal species in six of the country's nature reserves. They found that in years of lower-than-average fish harvests, biomass declined faster, and the number of reported hunters increased. In a monthly survey of 12 local markets across the country between 1999 and 2003, the researchers also found that when fish were scarce and more expensive, the supply of bushmeat rose.
That suggests, says co-author Andrew Balmford of the University of Cambridge in the U.K., that hunters are responding to an increased demand for bushmeat in the face of higher fish prices. The effect was stronger near the coast, Balmford notes, but because dried and smoked fish is sold far inland, the impact was seen across the country. Fish harvests had a bigger impact on the year-to-year size of land mammal populations than any other factor the team tested, Balmford says, including climate patterns and civil or political unrest.
The study is a clear signal that narrowly focused attempts to address either overfishing or bushmeat hunting will not work, says independent consultant and fisheries expert Ian Watson. "We need to look much broader to see how all the economic factors work together," he says.
That picture is complex. Although Brashares and his colleagues point a finger at agreements that allow subsidized fleets from the European Union to fish in the Gulf of Guinea, off the West African coast, Watson says that simply eliminating E.U. boats won't solve the problem. Vessels from Asia and pirate vessels without licenses would quickly fill any gaps they left, he says.