The male moor frog turns from brown to blue during the mating season. The red-eyed tree frog has three eyelids. Marsupial frogs have their young developing in pouches. The goliath frog can weigh up to 3.25kg. Frogs exhibit an incredibly advanced level of parental care. In short, frogs are very cool.
Apart from being amazing, anurans (and generally, amphibians) are vital for the functioning of a healthy ecosystem. Being predators and prey, connecting land and water, they are a key part of the food chain and sustain a rich biodiversity. Amphibians are also natural pest controllers, eating insects that can be a problem for crops or cause widespread disease. Alarmingly, according to the IUCN “nearly one-third (32%) of the world’s amphibian species are known to be threatened or extinct” and “at least 42 % of all species are declining in population, indicating that the number of threatened species can be expected to rise in the future”.
The main causes for this decline have been identified as habitat loss and diseases such as the chytridiomycosis, which is caused by a fungal infection. Additionally, the international trade for frog meat is putting immense pressure on populations, especially of the larger-bodied species. Frogs are a gastronomic delicacy of many countries, including France, Greece, Vietnam and the USA, and they are consumed by the hundreds of millions every year. In many countries in Africa and Latin America wild frogs are still collected for local sustenance. However, in the last 20 years countries like Indonesia, China and Taiwan have become major exporters of alive and dead frogs around the world. Unfortunately the rates of trade are considered by experts as unsustainable.
For centuries frogs have been part of the cuisine of many cultures, such as the Greek and the Roman (teixeira et al. 2001). Even the Aztecs were consuming frogs. In 2013, a team of archaeologists digging in Wiltshire, UK, found remains of cooked frogs dating back 10,000 years – long before the first records in France, despite the stereotype! However, In the last century the United States have seen extensive declines in their anuran populations due to overexploitation. During the 60’s and 70’s, France also saw a collapse in its native frog populations, consequently banning their harvest, and starting to seek market supply from abroad. Bangladesh and India became the main exporters of frogs, until they also experienced a major stock collapse. This lead to the 1985 CITES Apendix II listing of two of the most internationally requested species, the green pond frog (Euphlyctis hexadactylus) and the Indian bullfrog (Hoplobatrachus tigerinus). The listing preceded a total ban by these two countries on their exports a few years later, which allowed for frog population recovery.
The current situation
Nowadays Indonesia is the main exporter, with 5000 tonnes exported each year, and the EU is the largest importer followed by the USA. Between the main exported species we can find the giant Javan frog (Limnonectes microdon), and the American bullfrog (Lithobates catesbeianus). However, the EU does not record the imports to the species level, and export labels are often incorrect. Especially considering many frogs are exported skinned and frozen. Therefore, it is challenging to understand the scope of the effects of this trade. Moreover, often the state of the population in the country of origin is unknown, which complicates the assessment. Warketin et al. (2008) have underlined a parallelism between fisheries collapses and the frogs trade. People should be learning from past mistakes and avoid overexploitation, however the trade is continuing on the same path: first Bangladesh and India, and now Indonesia. “Will the extinction dominos continue to fall?”, they ask.
Is farming the solution?
It doesn’t look like it. Farming has proven economically unsuccessful in a number of countries, therefore only marginally alleviating the pressure on wild populations. Farms also tend to favour the spread of infectious diseases or pathogens such as the chytrid fungus in geographically distant areas, due to the trade in live specimens. Moreover, farmed frogs from elsewhere have the potential of escaping and becoming invasive, such as the American bullfrog in California and Europe.
Banned or certified?
The CITES listing and the subsequent ban in frog trade in Bangladesh and India and the harvesting of alive frogs in France were effective in allowing local frog populations to recover. However, it is known that bans have strong limitations, especially when the trade has a very high economic return, and might fuel a black market. A control in frog trade is problematic because reliable data on frog populations is scarce. To start with: how do we set a sustainable quantity allowed to be traded, if we don’t even know how many frogs are there in the first place? And how do we monitor that the regulations are actually implemented, especially when many frogs are unidentifiable when traded (e.g. only legs arriving at shipping points)?
I also see another issue here. Frog consumption is an important part of many cultures, all around the globe. Imposing a ban on the international trade, as well as on the local harvest, could be seen as an unfair imposition from international bodies over national customs. However, it is also true that even very limited, local consumption has severely affected frog populations (e.g. purple Indian frog).
Warkentin et al. suggested a certification, which would provide information on the country of origin and on the population conservation status, to be checked at processing points. The authors recognise this as a potentially costly regulation, however they regard it as possibly the best way of monitoring populations and developing a sustainable industry. I find this a very interesting idea, at the realisation that a total ban might not be efficient in the long run.
Sustainable diets: pest for pesto?
I think the frog trade is a complex matter that raises a wide discussion. Recently, there has been a lot of talk over the serious need for more sustainable diets, and not only from a biodiversity conservation point of view. The global food system requires a revolution. Globally 850 million people are starving while 1.5 billion people are overweight. Projects such as LiveWell for LIFE are working hard to raise awareness of the global impacts that our current diets are having in terms of greenhouse gas emissions, excessive land use and waste. However, with an ever increasing human population, and depleting food sources such as fish, it is likely that the pressure on frog populations will increase.
Perhaps the demand for frogs will always be there, and it will be difficult to render it sustainable by only focusing on regulating the current preferred species. So why not try and shift the consumption to pest species? This is what Professor Philip Hayward has suggested recently, suggesting that the Australian cane toads might be a good alternative. It would be a very economically profitable trade, and take pressure off some of the species mostly impacted by the current trade. Harvesting wild cane toads might also help the Australian ecosystems widely impacted by this invasive species. Fine food? I am not sure, but perhaps a grilled and spiced invasive cane toad might go down better than a grasshopper skewer.