"Lake Sebu tilapia farms" by fragment of angry candy via flickr
We've reported on farmed Atlantic salmon escaping into wild Pacific salmon habitat, and how farmed fish threaten marine life and human health . At the other end of the sustainability spectrum we've also highlighted the benefits of backyard aquaponics.
In Farming Fish For the Future Brian Halweil of the Worldwatch Institute looks at the state of aquaculture around the globe and offers insight into how farming fish can help feed people as well as facilitate the recovery of wild fish populations.
Fish farming has expanded to meet the soaring global demand for seafood. On average, each person on the planet is eating four times as much seafood as was consumed in 1950. The average per-capita consumption of farmed seafood has increased nearly 1,000 percent since 1970, in contrast to per-capita meat consumption, which grew just 60 percent.
In 2006, fish farmers raised nearly 70 million tons of seafood worth more than $80 billion-nearly double the volume of a decade earlier. Experts predict that farmed seafood will grow an additional 70 percent by 2030.
Poorly run fish farms can generate coastal pollution in the form of excess feed and manure, and escaped fish and disease originating on farms can devastate wild fisheries. For example, a fish farm with 200,000 salmon releases nutrients and fecal matter roughly equivalent to the raw sewage generated by 20,000 to 60,000 people. Scotland's salmon aquaculture industry is estimated to produce the same amount of nitrogen waste as the untreated sewage of 3.2 million people-just over half the country's population.
Making Fish Farms Sustainable
"The last wild ingredient in our diet is no longer completely wild," says Halweil. "This doesn't have to be a permanent situation, since wild fish stocks can recover. But as more coastal ecosystems are transformed into sites for fish pens, cages, and cultured seaweeds, fish farmers and the food industry will need to make ecological restoration as much a goal as meeting the growing demand for seafood."
Halweil defines six innovations that he says will help farmed fish feed the world, what he says "may in fact be the most hopeful trend in the world food system." These innovations are:
1. Ecological Aquaculture, including urban aquaculture;
2. Farming in the Warehouse, which amounts to closed systems that don't pollute habitat and ecosystems;
3. Cleaning Wastewater, farmed fish in Calcutta "feed on the 600 million liters of raw sewage that spews from Calcutta daily, turning a health risk into a key urban crop";
4. Restoring Habitats, "fish farming can help to restore degraded coral reefs and wetlands";
5. Eating Local Seafood, people who eat local fish, maintain local ecosystems;
6. Eating Little Fish to Save Big Ones, eat smaller fish like anchovies instead of feeding them to carnivorous farmed fish like salmon.
More on Fish Farms
Future of Food: Fish Farms in Condos
Deep Sea Fish Farm: Deep Trouble?
Fish Farm Taps Biodiesel From Fish Guts
More on Aquaponics
The TH Interview: Brian Naess of Snowcamp Aquaponics
Snowcamp Aquaponics: DIY Fish Farming With Zero Experience
DIY Aquaponics – A Video Round Up
Growing Power Milwaukee
The Urban Aquaculture Centre