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Gastronomic gastropods

Snail farming can be a very good business in areas where the local market is strong and where, as a result, over collecting from the bush has led to a shortage and boosted prices. Snails fit in well with other farming activities, helping to fertilize the soil prior to cultivation of other crops. And those of unmarketable size can be fed to pigs, shells included. But snails are not without problems, especially when exotic species are introduced, whether for farming or for biological control of a local 'agricultural pest' species. As with any livestock, mini or macro, it is easy to slip on the trail to success.

African snails on a plate!West Africa is home to several edible snails, but the most popular are the giant snail (Achatina achatina) and the big black (Archachatina marginata). The former reaches a bodyweight of between 80 and 250g in 18 months to two years, whereas the big black adult weighs about 350g or more. These are far larger than the European, Helix species which, perhaps undeservedly, have a reputation for superior taste and texture. It is not unknown for unscrupulous traders to stuff the shells of European species of snail with pieces of meat from giant African snails, thereby deceiving the consumer to enhance their profit. This practice will not, of course, work in the market places of West Africa where snails are usually sold live!

Snaileries can vary from a patch of fence-protected ground, sheltered from the wind, to a wooden box or movable pen. Also widely used are trenches or pits which, provided they protect the snails from predators (rats, lizards, centipedes etc.) also work well. Ash, neem or tobacco leaves help to deter natural predators and a site close to the home helps to deter human thieves.

Breeding stock can be obtained from a nearby market or collected from the bush. In either case, this at least ensures that the species is adapted to local conditions. Snails need food plants and, if on open ground, shelter plants as well. It seems that snails change their eating preferences as they age, the younger snails preferring leaves whereas the more mature enjoy fruit. Giant African Snails are apparently unwilling to tackle the skin of fruit or vegetables, which the grower must therefore slice or quarter in order to avoid excessive waste. A source of calcium is also important for shell formation. Ordinary school chalk works well but is expensive. Powdered oyster shells or poultry eggshells can be used if there are no other readily available sources of natural calcium. Humidity is essential at all times and snaileries must be watered when ambient humidity drops.

Even the best-fed snails may fail to grow well. One of the problems is their sensitivity to traumatic shock. The growing shell is very fragile and, if damaged, the animal's growth pattern is upset. The shell itself is protected by a membrane or cuticle and this does not regrow if removed by abrasion. The exposed shell is then vulnerable to attack by anything acidic. Most vulnerable are the hatchlings which, in the case of A.achatina, are tiny. This species may lay a clutch of several hundred eggs of about 5mm in length and the newly emerged snails are about the same length. In the case of A.marginata, there are fewer, larger eggs of about 1cm in length and the hatchlings have a better survival rate being more robust. Again, as with any livestock, management that is sensitive to the particular needs of the species, together with standard good practices of hygiene and protection, should ensure a reasonable success rate.

It may be that recognition of the need to conserve threatened wild species will change attitudes more effectively than the demands of would-be commercial growers for information. Research by CIRAD (Email: brescia@cirad.nc), on conserving a snail indigenous to New Caledonia (Placostylus fibratus), is leading to the development of controlled rearing methods in order to conserve wild stocks, now much depleted by over collection. In the last five years, it is estimated that stocks have been reduced by 45%. P.fibratus is an important source of protein and income, and to outlaw its collection from the wild would pose serious problems. By developing ways of farming the snail, the natural population can be both conserved and reinforced and the people maintain their supply of snail meat and their income.

There is still much need for research on snail farming and one of the challenges to be overcome is to convince government authorities that such research is necessary. Snails may be a delicacy but regrettably not everyone thinks of snail farming as an activity indicative of progressive agriculture.

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