Snails fun to farm

Don Picken, of Wellington, asks: Is there any research going on concerning farming snails in New Zealand?

Fabrice Brescia, a zoologist in New Caledonia who is studying the conservation of snails for a PhD at Massey University, responds:

 I haven't heard of a scientist in New Zealand studying edible snails and their farming (heliciculture).

Several species of snails can be farmed using several techniques. Free-range snail farming is often used. This is based on the Italian method of breeding snails using the biological cycle of raising and growing them in open pastures of fresh vegetables in a natural environment, allowing them to grow as nature intended.

There is an organic farmer of free-range snails in Hawke's Bay.

Snails – terrestrial molluscs – are hermaphrodites, but they have to mate before laying eggs some days later. One snail can lay eggs up to five times a year, with between 80 and 140 eggs laid each time. The incubation period varies between 15 and 30 days according to climatic conditions.

The garden snail, Cantareus aspersa, formerly called Helix aspersa and sometimes known as petit-gris, weighs about 10 grams and is the species of edible snail usually farmed worldwide.

Petit-gris snails reach adulthood and can be harvested for eating 14 to 18 weeks after hatching. Adults are characterised by a shell aperture with a thick lip.

Sometimes, more intensive techniques are used, with reproduction and nursery raisingbeing done indoors, in climatised areas, and fattening being done outdoors in special pens.

Snails are fed with a dry meal, rather than a green fodder. It is more efficacious, hygienic and less expensive to produce.

Apart from these commercial farming considerations, some scientists also try to farm endangered snails for the conservation of rare species. For example, in New Zealand and New Caledonia, we have farmed flax-snail species of the genus Placostylus.

These snails are often threatened by loss of habitat, predation by introduced rodents or over-collection in the forests of New Caledonia because they are favoured as food.

Conservation trials are based on amplification of threatened Placostylus populations in captivity, with the idea to release these captive snails for reintroduction (to create a new snail population in areas where they are extinct), supplementation (to help very small snail populations by adding new specimens) or translocation (to create a new snail population in another place, such as a predator-free area).

Send questions to Ask A Scientist, PO Box 31-035, Christchurch 8444, or email questions@ask-a-scientist.net.

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