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Closing the aquaculture loop

(post, Twilight Greenaway)

I enjoyed Tom Philpott's [initial observations http://gristmill.grist.org/story/2009/2/3/165311/7959] from the Seafood Summit, which he describes as a "complex dance between the fish industry and the NGOs that monitor them."

Like Philpott, I am very interested in the idea of integrated multi-trophic aquaculture (IMTA). Now taht many of us understand the dangers of monocropping on land, it's time to start drawing people's awareness to the ways that large-scale aquaculture "tend to require huge amounts of inputs and throw off massive amounts of waste." 

On the other hand, he points out: The best sustainable-minded farmers figure out ways to "close the loop" through on-farm biodiversity." 

It's a simple idea: "rather than let huge concentrations of fish manure from, say, salmon cages foul coastal waters, you place shellfish, which filter and are nourished by the manure, slightly downstream from your salmon cages; and then seaweed further downstream still, which takes up remaining nutrients from the manure."

And, while very few fish farms appear to have this approach, it strikes me as such a no brainer.