綠化的一角來養魚

Fish Farms, With a Side of Greens

綠色的一角來養魚

Jeff Redmon 報導

Sweet Water Organics, a company in Milwaukee, raises perch and grows leafy green vegetables in a former factory.

Sweet Water Organics, Genevieve Roberts攝影

Aquaponics-a combination of aquaculture, or fish cultivation, and hydroponics, or water-based planting -utilizes a symbiotic relationship between fish and plants. Fish waste provides nutrients for the plants, which in turn filter the water in which the fish live. Cuttings from plant are composted to create food for worms, which provide food for the fish, completing the cycle.

“Aquaponics is a method of delivering multiple crops with minimum input, through a closed-loop method of farming,” said Charlie Price, founder of Aquaponics UK, the nonprofit organization that runs the farm.

A kilogram, or 2.2 pounds, of fish food, produces at least 50 kilograms of vegetables and 0.8 kilogram of fish, he said. “As the ecosystem becomes self-sustainable, the fish food comes from the worms, so the entire cycle is free.”

Mr. Price’s organization is working internationally with food production projects in India, Afghanistan and several African countries, including Uganda, Kenya and Namibia. But it also works closer to home. Its next project is a city farm shop in London at which people will be able to pick their own salads and choose fish for their supper from giant tanks.

The store, called Farm:shop, in the Borough of Hackney, was created by Something & Son, a design company, working with the local council. It hopes to make direct links between the city neighborhood and the realities of farming. A location has been secured, and the project is in the late stages of acquiring funding.

The potential for urban farming is being explored in Milwaukee, where some of the leading aquaponics entrepreneurs are based. Sweet Water Organics, an urban aquaponics company, raises perch and leafy green vegetables in an old factory that housed a mining company until the 1950s. The farm, founded by James Godsil and Josh Fraundorf in January 2009, has sold thousands of fish and produces about 70 kilograms of vegetables a week. It is expanding rapidly, and plans to produce between 360 and 450 kilograms of greens a week and to grow tens of thousands of kilograms of perch in coming years.

Mr. Godsil and Mr. Fraundorf learned the techniques largely from Will Allen, an urban farmer and winner of a MacArthur “genius” fellowship, and through trial and error.

“We believe this is the world’s first effort to turn a factory into a fish and vegetable farm, and it’s a complex proposition,” Mr. Godsil said. “We’ve experimented with 40 types of lettuce, settled on three or four, and we’re now trialing spinach.”

The farm started with a $50,000 investment but has attracted about $1 million in funds over the past 20 months and partnerships with the Milwaukee School of Engineering and informally with the University of Stirling in Scotland. It is discussing the prospect of a $30 million concept for Sweetwater villages, which would have community-scale manufacturing, restaurants and cafes with food produced from aquaponics.

The farm is receiving support from the University of Wisconsin and Sea Grants, a U.S. government program, to grow yellow perch and possibly blue gill, species indigenous to the Great Lakes but in decline. “The fish it produces are a 21st century form of protein that won’t harm planet earth,” Mr. Godsil said.

Industrial aquaponics is still in its infancy, with only five facilities of more than 0.4 hectare, or one acre, operating in the world, although interest is growing, particularly in areas with water shortages. Aquaponics use between 80 and 90 per cent less water than traditional growing methods.

In Barbados, where fresh water is scarce and 80 per cent of food is imported, according to the Inter-American Institute for Cooperation on Agriculture, a project known as “Aquaponic island” started last year, with a goal of educating farmers about the benefits of aquaponics to make it their technology of choice in four years. The project has funding from the United Nations Development Program, the Barbadian Ministry of Agriculture, the institute and a community group, the Baird's Village Aquaponics Association. A commercial-scale system was set up at Baird’s Village, and this year aquaponic systems are being introduced to many of the island's schools.

In Australia, where farmers have struggled with drought for the past decade, backyard aquaponic systems have grown in popularity. Joel Malcolm, who opened the world’s first aquaponics retail store, Backyard Aquaponics, in the Australian city of Perth, sells about 300 systems a year.

“With water restrictions enforced in almost every city around the country, people just can’t have their traditional vegetable garden,” he said. “Being able to produce your own chemical-free fish and vegetables in your own backyard not only saves money but also provides enjoyment and satisfaction. Lately there have been quite a few schools installing systems here as learning tools for the kids.”

While backyard systems are in their infancy in the United States, they are growing in popularity, with estimates that there may be 800 to 1,200 aquaponics setups in American homes and yards and as many as 1,000 more in schools, according to the Aquaponics Journal.

Could this almost-waste-free food production method be the miracle solution to tackle worldwide food shortages that some expect? Brett Roe, who investigated ecologically integrated production systems at the University of Queensland in Australia, cautioned that it might not be a cure-all. “Aquaponics offers decentralized food security on a small scale, and reuse of resources,” he said. “Every little bit helps. But in developing countries it may make better sense to culture fish in ponds and use the wastewater on land-based crops; a simple linkage of aquaculture and crop farming that has the same general effect of reusing resources and can be practiced in a larger scale of economy.”

While still in its fledgling stages, Mr. Godsil said the potential of aquaponics was “breathtaking.”

“Aquaponics has inspired pragmatic utopian visions, that keep getting validated by the facts. We need solutions to what could be a Pearl Harbor moment for the species, if global warming trends continue the way Al Gore and scientists predict,” he said referring to the former U.S. vice president.

Mr. Price of Aquaponics UK said: “Given our requirements to provide significantly more energy and food in the next 20 years, aquaponics can play a vital role. It isn’t a new technology – in fact it was first documented by the Aztecs-but when adopted in our new climate it provides a highly profitable and sustainable food production system.”