permaculture

[Robyn Francis <robyn@permaculture.com.au>]

The lessons from Bill's systems at Tagari are not encouraging or promising

The "chinampa" wasn't built in a swamp, it was excavated on dry land and only 
had water in the channels during the wet season, it soon became over-run with 
weeds and a maintenance liability. The lesson: chinampas are swamp-land 
systems, don't try to re-create them on dry land unless you've a constant 
supply of water coming through the system year-round.

The aquaculture system at Tagari was a series of standard fish farming ponds 
designed for controlling water levels, harvesting etc, and stocked to maximum 
density with aeration and feed inputs, with native freshwater fish, Silver 
Perch. It had to go through all the government licensing procedures for 
commercial fish farming. After a few good seasons and harvests disease got in 
and effectively shut the operation down. The disease was an endemic (locally 
occurring) freshwater disease, local species in streams seem to have 
resilience but in an intensive or semi-intensive aquaculture disease can wipe 
the entire fish stock out in no time.

More aquacultures fail than succeed, mainly from fish diseases. I see it 
again and again, also with aquaponic systems. A local organic aquaponic 
system integrating fish, earthworms and vegetable production after a number 
of successful years is now struggling with fish disease. Fish disease has 
shut down hundreds of fish farms in Taiwan as well as Australia.

It seems the only systems that don't readily go down with disease are with 
telapia, which seems to be able to cope with bad water quality better than 
most other fish species. 

BTW Telapia should NOT be introduced into systems in Australia.  
Unfortunately there are several river systems in Nth Queensland and Western 
Australia that had telapia introduced with devastating impacts on habitat of 
native species. 

Robyn

On 08/10/2012, at 11:08 PM, Cory Brennan wrote:

> 
> What lessons are there from Mollison's aquaculture/chinampas system at 
> Tagari? 
> 
>