Declining fish supply linked to wildlife consumption in West Africa
The authors of a 30-year study suggest that declines in fish supply in Ghana can lead to regional increases in the hunting, trade and human consumption of wildlife in this West African nation. Declining fish stocks suggest marine resources are nearing collapse due to overfishing by regional and foreign fleets, most notably fleets subsidized by the European Union. A fisheries collapse would have widely felt consequences for regional economies, human food supply and efforts to conserve nature on land, a new study suggests.
These findings appear in the 12 November 2004 issue of the journal Science, published by AAAS, the nonprofit science society.
The authors call for improved fisheries management from local nations and from the European Union in order to protect biodiversity and promote both food security and poverty eradication. They also emphasize the need for ecologically sound, inexpensive protein alternatives to wildlife and better conservation measures to protect remaining wild animal populations.
The researchers analyzed records of fish supply, fish abundance, wildlife hunting pressure and wildlife abundance. They found that years of poor fish supply coincided with increased hunting in nature reserves and sharp declines in wildlife abundance. "Our study presents very strong evidence showing how human food supply can be directly related to conservation of wildlife," said Science author Justin Brashares from the University of California-Berkeley in Berkeley, California and the University of Cambridge in Cambridge, UK.
Brashares hopes this work will increase awareness of the idea that conservation can not occur in a vacuum. Local efforts to conserve a given species or system requires, for example, an appreciation of the ways in which humans and their resources interact across ecosystems.
Wild animals from the tropics that are hunted for eventual human consumption are often grouped together under the label "bushmeat." Primates, big cats, elephants, antelope, porcupines, giant snails, tiny songbirds – and most any other wild land animal from the tropics that hunters kill and sell or consume themselves – can be considered bushmeat. The multi-billion dollar bushmeat industry is a key contributor to local economies throughout the developing world. It is also among the most immediate threats to tropical wildlife.
The new Science study links escalations in the bushmeat trade to declines in fish supply and suggests that overfishing in the region will further complicate biodiversity conservation on land. Connections between the over-harvesting of fish and increased pressure on terrestrial wildlife are probably not restricted to Ghana or West Africa. Other industrialized nations need to recognize the consequences of their subsidized fishing ventures on terrestrial ecosystems in the developing world, according to Brashares.
The authors calculated the total catch of the European Union foreign fleet in Africa using fisheries harvest data from the Food and Agriculture Organization of the United Nations (FAO). The declines in per capita fish supply the scientists cite are largely caused by increases in human population size. Fish catches have increased during the study period due to greatly expanded fishing efforts. "We need people working together across disciplines to look at how losses of marine resources are impacting land resources, and vice versa," Brashares said.
Brashares first became interested in the bushmeat trade when he saw its impact on the West Africa ecosystems he was studying as a doctoral student. When a former vice president of Ghana made the observation that political and social discontent nearly always occurred in bad fishing years, Brashares considered other phenomena that could be linked to bad fishing years. "I wondered if I could uncover a signal linking fish supply to wildlife declines and the bushmeat trade," said Brashares.
While scientists had previously considered this possibility, there were no clear data linking fish supply to terrestrial conservation issues at large scales. Brashares and colleagues began to pull the pieces together using long-term records of wildlife declines and hunting activity collected by wildlife rangers working in terrestrial wildlife reserves in Ghana.
The scientists report that the abundance of 41 species of wild carnivores, primates and herbivores (measured as biomass) in six nature reserves in Ghana declined by 76 percent from 1970 to 1998.
From 1976 to 1992, Brashares and his colleagues also saw that the number of reported bushmeat hunters in five wildlife reserves increased when regional fish supply dropped. In addition, bushmeat sales in 12 rural markets increased when fish supply in those same markets dropped. Together, these findings suggest that people substitute wildlife for fish in years of fish scarcity.
The researchers also report that fish supply and wildlife declines were related most closely in the wildlife reserves nearest the coast – a finding that further strengthens the link between fish supply and the bushmeat trade. With nearly half of Ghanas human population of 20 million living within 100 kilometers of the Atlantic coast, the widespread loss of jobs and income associated with fishing harvests draws people to bushmeat hunting for both income and food, the authors concluded.
The authors propose the politically and ecologically difficult task of establishing alternative protein supplies in West Africa.
They also propose increases in the size, number and protection of wildlife reserves in Ghana and other parts of West Africa. While these protective actions may not offer a long-term solution to concerns over human livelihoods and protein supply, they are likely the most immediate prospects for slowing the regions catastrophic wildlife decline, the authors write.
A "Review" article by William Adams from the University of Cambridge in Cambridge, UK and colleagues, also in the 12 November 2004 issue of Science, takes a closer look at the connections between biodiversity conservation and the eradication of poverty. With hopes of promoting clearer understanding, the authors offer four different ways that people and organizations often look at the relationship between biodiversity conservation and poverty elimination.
"The larger challenge is to allow human society to meet its potential and share the fruits of economic growth while sustaining a biosphere that not only sustains full ecological functions, but which retains its living diversity," the "Review" authors write.
Jessica Lawrence-Hurt | EurekAlert!