Living Machines

THE LOKO KUAPA WAS a simple system. Ancient Hawaiians
piled lava rocks in shallow seawater to form walled pools. The
small fish that swam in at high tide got trapped and grew to
harvest in a natural cage kept clean and balanced by the washing
waves.

Today?s high-volume industrial fish farming is not so benign.
The fish produce a lot of waste that pollutes the surrounding
water, and when they escape, they can spread their inferior (or
perhaps even genetically engineered) traits into the wild. What?s
more, in order to taste good, the farmed fish are fed meal made
from large amounts of the wild fish they eat naturally.

But, as Melissa Pasanen writes in The Art of Eating
(#61, 2002), environmental designer John Todd and his colleagues at
Ocean Arks International (OAI) are working to invent better fish
farms far from the ocean. As president of OAI in Burlington,
Vermont, Todd leads an effort to devise new ?ecotechnologies? for
raising fish, complete with a series of linked, miniature
ecosystems for purifying their water and producing some of their
food. Often called ?living machines,? Todd?s recent projects
include a system for growing a popular African freshwater food fish
called tilapia.

In an early step, Todd and his crew mix straw with spent grains
from a local brewery to grow organic mushrooms, the first of
several crops that can be produced by the process. After the
mushrooms are harvested, the remaining material is ready to be used
to raise worms for feeding the tilapia.

The tilapia live in a tank whose water circulates
through three other tanks, each holding a different but related
aquatic community. The tanks nurture plenty of duckweed and algae
that the fish will eat along with their worms. This second food
source creates a highly efficient system that actually consumes
less animal protein than it produces. (Conventional fish farms tend
to use far more.) Meanwhile, other rooted plants in the tanks are
naturally processing waste from the fish. Compost from the system
can also be used to fertilize various crops grown in nearby
plots.

The system isn?t perfect, yet. As tropical fish,
tilapia need water heated to 82? F?an expensive
proposition in Vermont. The team has tried raising yellow perch, a
cold-water fish, but their greater need for animal protein upsets
the system?s efficiency.

The real solution may lie in tying these living machines into a
larger system. One example is Burlington?s Intervale project?the
nation?s first agriculturally based ecopark. Once a wasteland of
old cars and other junk, the 700-acre area known as the Intervale
is now a patchwork of small farms, composting facilities, and open
space. It will soon include food processing facilities and
greenhouses for winter farming, reports Jill Bamburg in
Yes! (Fall 2002). One greenhouse will house an OAI
fish farm, this time warmed with excess heat generated by a
neighboring electrical power plant that runs on wood waste from
Vermont?s mills.

?The more biological complexities you develop in a system, the
more robust it becomes,? explains OAI?s David Demarest. The
Intervale system will use straw from nearby fields and grains from
the local Wind Harvest Brewery?s homegrown hops and fruit. The
larger facility and inexpensive heat should double the harvest of
both mushrooms and tilapia, and perhaps reach its goal of
financial viability. Simple, smart, and sustainable?just like a
loko kuapa.

Lisa Hamilton is a freelance writer living in Mill Valley,
California
.

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