Monday, April 25, 2016

Possibility of Pomacea as Temperate Micro-livestock.


Pictured is a tropical water snail, which I believe to be Pomacea bridgesi, which has grown to 1.75 cm over two years, possibly less, in an outdoor aquatic plant tub in temperate Wellington, New Zealand (hardiness zone 9). This species is harvested for meat in tropical and subtropical regions (1), no doubt when it has grown to its much more impressive full size of 4-6 cm. 

Growth appears to be dependent on heat, seems to be very slow in winter, much faster in hot weather, and it has been an unusually long, hot summer. Based on reports of growth rate in tropical countries growth is much slower here than there, but I will be watching with interest the progress of this and around 100 babies, in the coming years.  At this stage I'm only reporting on them as a potential temperate micro-livestock, since I was so surprised they even survived and reproduced outside not to mention one growing to an almost respectable size. 

Slaughtering snails for meat might raise fewer ethical and psychological issues for people who would normally avoid slaughtering complex animals for meat. I'm not sure I'll ever be slaughtering them for meat myself. I'm more interested in the potential for others who want to produce their own meat, especially in squeamish suburbs (or perhaps even apartment blocks, they could conceivably grow in tubs on balconies) .

Another advantage is it appears to require little care or feeding, I have it in tubs with edible aquatic plants, such as Nymphaea odorata, and Aponogeton distachyos, they seem to mainly eat the algae growing on the plants, though the Aponogeton occasionally looks pretty mauled. There might be potential to supply them with foods that make them grow faster.

An additional advantage is they don't need elaborate containment structures like gourmet land snails, they seem to stay in, or very near the water. Though it appears they can attach themselves to animals that visit the water and escape that way, presumably this explains how a number ended up looking quite happy in my dog's water bowl some distance away inside!

A disadvantage is they often lay eggs on, and cling to the underside of the edible aquatic leaves I harvest for dinner. It can be fiddly getting them all off. I understand some water snails have extremely toxic eggs, I believe these are species with very brightly colored eggs, showy displays are usually a sign of danger in the animal, plant and human worlds. The eggs of my snails are transparent, indicating they are "hiding" because they are non-toxic, probably I have eaten a few of them by accident with no noticeable effect. But plants are more my area than snails, I strongly encourage doing your own research or find an expert on this subject. 

Another disadvantage is they would be difficult to remove from a tub or pond once established, I tried with chlorinated water which kills many fish, they loved it. Perhaps a traditional fish toxin like saponins from various plants would be worth a try, otherwise complete draining might work, but they actually have lungs as well as gills so might even survive that, at least for a while.  

I discovered they could survive outside entirely by accident, I was raising them indoors in a tank, it didn't seem to be going well, the older large ones, purchased at a pet shop, kept dying. So I gave up on the project and dumped the water, containing a few tiny baby snails, into some of my outdoor water plant tubs expecting that to be the end of it. Much to my surprise I noticed eggs everywhere shortly after. So they are able to go through their full reproductive cycle when very small, they do not need to grow large for this.

1) Apple Snails in the Aquarium. Dr G Perera, J Walls 1996

    

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