Using 30 years worth of census data collected monthly by rangers in six nature reserves in Ghana, the researchers have found a direct link between fish supply and the demand for bushmeat in Ghanaian villages. Bushmeat is any wild species taken from public land and sold for consumption.
The group's findings will be published in November 12 issue of the journal Science.
More than half of Ghana's 20 million people reside within 100 km of the coast, where fish are the primary source of dietary protein and income.
Looking at data for the years 1970 to 1998, researchers found that in 14 local food markets, when fish supply was limited or its price increased, residents substituted bushmeat as an alternate source of affordable protein and the number of bushmeat hunters observed by rangers in parks increased. Overall, the wildlife harvest has contributed to a 76 per cent decline in the biomass of 41 species of mammals in parks since 1970.
The bushmeat trade in Ghana is estimated conservatively at 400,000 tons per year. Species affected include several species of antelope, carnivores and small primates.
During the same period, trawl surveys conducted in the Gulf of Guinea, off Ghana's coast, since 1970 along with other regional stock assessments, estimate that fish biomass in nearshore and offshore waters has declined by at least 50 per cent. In the same period, there has been a threefold increase in human populations in the region.