World Rainforest Day: Goliath frogs need urgent conservation measures

Goliath frog population is estimated to have halved in the last 15 years

By Abhijit Mohanty
Published: Monday 22 June 2020
The Goliath Frog, found in the rainforests of central Africa, is the largest amphibian in the world. Photo: istock

Frogs are perhaps the least-studied species in the diverse ecosystems of Central Africa. Many amphibian species are still waiting for their scientific discovery.

According to the International Union for the Conservation of Nature (IUCN) Global Amphibian Red list Assessment of 2008, about 1,856 species of amphibians are globally threatened, making them the most threatened species, compared to mammals and birds.

In Cameroon, 57 of these species are endemic, predominantly found on the highlands, while 63 species are threatened with extinction, according to IUCN, 2012.

Goliath frog

Conraua goliath, also known as ‘goliath frog’ is the largest frog in the world, with some adult individuals weighing as much as 2.99 kilograms and measuring more than 33 centimetres (cm) in length, excluding their legs, when fully grown. And their eyes are about 2.5 cm wide, which is larger than the average eye size of humans. 

They are found only in the tropical rainforest of central Africa, within the south western part of Cameroon and north of Equatorial Guinea. Scientists believe the goliath frog has been around for over 250 million years.

One of the most interesting behaviours of this species was discovered in a recent study, which revealed that they build nests for their eggs and tadpoles by moving rocks more than half of their body weight.

This species has a limited geographic distribution, narrow ecological requirements and is largely hunted by the local communities in Cameroon and Equatorial Guinea for consumption and pet trade.

Goliath frogs are exported to the US for participation in frog jumping contests. Climate change, deforestation, commercial agriculture, and over-hunting are some of the prime causes driving this species to extinction.

As a result, the goliath frog has been classified as an ‘endangered species’ by IUCN and as a protected species of class ‘A’ according to wildlife law in Cameroon. According to a recent estimate, the total population of goliath frogs has dropped by at least 50 per cent over the last 15 years. They are on the brink of extinction, warn local amphibian conservationists. 

Mount Nlonako

Mount Nlonako in Cameroon harbours 93 types of amphibian species, including the goliath frog. The 93 species constitute 32 per cent of the 236 amphibian species recorded in Cameroon. Biologically, Mount Nlonako has been termed as a veritable hotspot of African amphibian diversity.

The area is characterized by high amphibian, mammalian and reptilian species richness and therefore ranked amongst the top 10 mountain ecosystem biodiversity hotspots in central Africa. Due to lack of employment and livelihood opportunities, locals in and around the Mount Nlonako area often engage in hunting and poaching of wildlife.

On an average, the local hunters hunt twice a week and harvest an average of 10-15 frogs a week, resulting in an estimated harvest of 19,440 frogs every peak season, mostly during the dry season, revealed a study conducted in Mount Nlonako by the Environment and Rural Development Foundation (ERuDeF) in 2016.

ERuDeF is the recipient of the Whitley Fund for Nature Award for significant contribution in conserving the critically endangered cross river gorilla and endangered Nigeria-Cameroon chimpanzees.

“Earlier, in one night, I used to catch 8 to 12 goliath frogs,” Julius Nde, a frog hunter from Magamba village, Mount Nlonako, Mungo division, Littoral Region, Cameroon, told me. “But now, catching even 2 to 5 of them in a night is difficult. They are not plentily available now in the area”, adds Nde. Hunters like Nde mostly use poisons, nets, traps and snares to hunt goliath frogs.

“It tastes like chicken,” says a local farmer, who often buys frogs from Nde. Even their tadpoles are harvested by the locals for consumption. “We have been eating goliaths for years. It is good for children and pregnant women. But you should eat it when it is fresh,” he adds.

Some local journalists also reported that many of these live frogs are actually trafficked to neighbouring countries like Nigeria, Congo and Gabon. “We get a higher price of bush meat in Nigeria,” Philip Nja, a bushmeat hunter, told me. “But, you need to be very careful. If the forest department catches you, you will need to pay a fine.” 

Photographer Cyril Ruoso, spent a month documenting the goliath frog in Cameroon. He says, “All the hunters I talked to said they need to go farther and farther to find the frogs. And the average size of the frog is going down.”

Habitat lost and encroachment has significantly contributed to the dwindling population of goliath frog in the tropical rainforest of Mount Nlonako.

Human encroachment and deforestation

“Increasing human encroachment in the area for agricultural farmland has resulted in deforestation and habitat degradation,” Tim Killian from the Amphibian Conservation Initiatives at ERuDeF, told me.

Deforestation is one of the principal causes for shrinking habitat and fragmentation in this area. About 90 per cent of the local population depends on agriculture as a source of primary livelihood. Large portions of the forest are being frequently converted into farmlands and to open new ones. Hydroelectric dams are also a potential threat to this species.

To make the situation worse, excessive application of chemical agro-inputs and toxic waste disposal such as pesticides, fertilisers and effluents from agriculture harms herpetological species through mortality and reduced reproductive success rate.

“Earlier, the farmers used to practice subsistence farming and supplement their household incomes by collecting forest-based resources,” Kari Jackson, executive director at SURUDEV, a not-for-profit organisation, working with the indigenous and forest-dwelling communities to conserve threatened species in the Northwest and Southwest regions of Cameroon, told me.

“Recently, farmers have started cultivating cash crops including cocoa, banana, pineapples and applying chemical inputs. This is negatively affecting the biodiversity of the area,” Jackson says.

Killer fungus

The status of goliath frogs in Equatorial Guinea is even more pathetic. In addition to threats from poaching and habitat destruction, the species now facing a deadly pathogenic chytrid fungus which has caused fatal fungal infections, leading to a significant drop in their population.

As a result, the government of Equatorial Guinea has limited their exportation to only a maximum of 300 frogs per year.

Today, very little information is available on the ecology and parasites of goliath frogs. Conservationists say that amphibians host several hematophagous vectors in their aquatic and terrestrial habitats which infect them with a wide variety of intra and extra-cellular blood parasites. This includes viruses, rickettsiae, species of several genera of protozoa, yeast and microfilariae.

Conservation practices 

Daniel Ngulffo Nguete from Centre for Research in Infectious Diseases and Chares S Wondji from Liverpool School of Tropical Medicine observed in their research that, “The environmental conditions and habitat play a critical role in microfilaria infection dynamics of goliath frogs populations.”

Thanks to some promising ex-situ conservation efforts in Cameroon, an attempt has been made to rear this species in captivity, local amphibian conservationists, said.

Gonwou Nono LeGrand, a herpetologist from the Cameroon Herpetology Conservation Biology Foundation, is partnering with scientists from the Museum für Naturkunde in Berlin to launch the first captive breeding programme for the species. In this context, a better understanding of the genetic diversity and population structure as well as evolutionary relationship of this species is crucial to improve future conservation initiatives.

However, the importance of in-situ conservation is equally critical, local civil society organisations emphasised. There is an urgent need to promote multi-stakeholder engagement and community-based outreach programmes.

Livelihood and sensitisation

Poachers, hunters, farmers, traditional rulers and members of village forest management committees should be sensitised and empowered to become local custodians of biodiversity. There is a need to develop an integrated ecological model using remote sensing systems, that will further enhance our understanding of the distribution and density of goliath frogs in their habitats.

“We need to provide alternative livelihood opportunities to the local hunters,” Tansi Godwill Tansi, founder and executive director of ECoDaS, a not-for-profit organisation, working in collaboration with the World Wide Fund for Nature and Arcus Foundation in Cameroon, told me.

“There are so many cases where die-hard hunters are being transformed into dedicated conservationists,” he said.

According to Tansi, people can substantially reduce the rate of frog hunting and bushmeat trade in the region by providing skill-building programmes to the local communities on sustainable agriculture, bee-keeping, poultry and piggery farming.

“Often, there are solutions in the problem itself,” Agbor Njingo Nkeng, a PhD scholar studying wildlife ecology management, at the University of Dschang, told me. “If empowered and sensitised, the local communities, who have been hunting goliath frogs and other amphibian species, could become the guardians of these endangered species in the future.”

Strengthening the conservation culture in communities will initiate awareness and commitment to the conservation of threatened species. “Promotion of local stewardship is key to conservation,” says Nkeng.

Goliath frogs play a vital ecological role in the food web by regulating the population of many species, as well as being food for others. They are often considered to be good indicators to wider ecosystem health. Therefore, the extinction of this species will cause an ecological imbalance in and around its habitats.

“We need to act now. Or we may lose this spectacular creatures of our planet,” concludes Nkeng.

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