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.