Over-fishing Off Ghana Linked to Rise in Wildlife Hunting, Science Reports

A Ghanian wildlife ranger holds a waterbuck antelope (Kobus ellipsiprymnus) killed by bushmeat hunters weeks before. Image courtesy of Justin S. Brashares

[A news release on the study is available in French and Japanese on EurekAlert!]

The depletion of fish in the waters off of Ghana is leading to a dramatic increase in the trade and consumption of wildlife, including antelopes, elephants and monkeys, according to a 30-year study published today in the journal Science. Fish supplies are nearing collapse because of over-fishing by regional and foreign fleets—especially those subsidized by the European Union—and that is having economic, environmental and human consequences throughout the region, the report says.

The study, published in the 12 November 2004 edition of Science, points up the tenuous balance of natural ecosystems, and the close relationship between food supplies, population growth, poverty and conservation efforts. It is the first to provide evidence supporting conservationists' long-held suspicion that bushmeat increasingly is a supplement to fish as a source of protein for Ghana's rapidly growing population. But the trend apparently has contributed to the extinction of almost half the species studied in some reserves, the authors found.

"What we found was that years of below-average fish catches had greater declines of wildlife on land," said Science author Justin Brashares Thursday in a global teleconference with reporters. "We saw this correlation between fish supply and wildlife declines as providing evidence that people are turning to wildlife as a substitute for fish when fish becomes unavailable.

"This link is identified not only in other parts of West Africa now, but certainly in other parts of Africa—including Central, East and Southern Africa—parts of South and Central America and parts of Asia as well."

Brashares is an assistant professor of ecosystem sciences at the University of California, Berkeley's College of Natural Resources. He began the work as a post-doctoral researcher at the University of Cambridge in the U.K., and collaborated with researchers in Africa and from the University of British Columbia in Canada, the Ghana Wildlife Division and the Wildlife Conservation Society in New York.

The researchers analyzed records of fish supply, wildlife abundance and wildlife hunting dating back at least 30 years, concluding that stocks of both "may be overextended and near collapse," Brashares told reporters. The abundance of large mammals in Ghana's wildlife reserves has fallen 70 percent in the past three decades, the authors found, while fish stocks along the West African coast have declined by as much as 80 percent.

Among the fish that have declined are shark, snapper, anchovies, mackerel and tuna—all of which are popular on dinner tables in Europe and elsewhere.

The EU maintains the largest foreign fleet off the West African coast, the study says. Its fish catches increased 20-fold from 1950 to 2001, and its financial subsidies to the fishing crews jumped from $6 million in 1981 to more than $350 million in 2001.

"The continued overexploitation of fish stocks and wildlife resources will result in a great loss of biodiversity in the region, which would be of great global concern," said Brashares. "Perhaps more devastating will be the loss of this vital source of food and income for millions of Africans."

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.

Brashares, hopes the 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." Included in wildlife menu are primates, big cats, elephants, antelope, porcupines, giant snails, tiny songbirds—and most any other wild animal from the tropics that can be hunted, trapped, traded and consumed.

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 suggests that over-fishing in the region will further complicate biodiversity conservation on land. 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). Fish catches actually have increased during the study period due to greatly expanded fishing efforts, but that has been offset by gains in Ghana's population—from 6 million in 1957 to nearly 18 million in 1996. As a result, they found, supplies of fish per capita have declined.

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.

While there are some papers suggesting that conservation and poverty-eradication efforts can be balanced to produce a win-win situation, Adams told reporters in Thursday's briefing that there's also literature suggesting that conservation increases poverty, and that poverty-reduction efforts cut into conservation.

The problem "is simply expressed," Adams said, "and extremely difficult to solve."

In an earlier interview, 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," he explained.

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 Ghana's 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. For example, they say, efforts could be undertaken to build up regional livestock and agriculture. But, they write, such an effort could take decades to implement and faces "enormous economic, regulatory, and political hurdles."

More immediately, they say, limits could be imposed on the foreign fleets that fish off West Africa. "Over the longer term," they write, "intensive management to enhance fish stocks and stabilize harvests must become a regional conservation and economic priority."

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, the authors say, they likely offer the most immediate prospects for slowing the region's catastrophic wildlife decline.

— Daniel B. Kane and Edward W. Lempinen

11 November 2004