As the world population grows, and as people are lifted out of poverty and start to enjoy a healthier diet, the world is going to need more food. At the same time, soil depletion, climate change and unsustainable water use are making food production more challenging.
There’s no magic solution to increasing the amount of food the world can produce, but lots of promising avenues to explore. Solutions include making better use of what we already have by reducing food waste and choosing less meat, to new techniques such as urban intensive agriculture or precision farming.
Among the more unusual suggestions is ocean farming. By farming the seas, you can circumvent pressure on land and freshwater altogether.
Greenwave is a pioneering company that has researched techniques to farm the entire water column, making small scale but highly productive sea farms. They claim that their model can provide 20 tonnes of sea vegetables and 500,000 shellfish per year from an acre of ocean.
It works by trailing a network of ropes from buoys. Kelp and mussels grow on the ropes, with oyster and clam cages below them. These can all be harvested, but they also create habitats for other creatures, increasing rather than depleting marine biodiversity.
Sea farming promotes the growth of existing native species, requires no inputs of fertiliser, pesticides or freshwater, and it sequesters carbon and nitrogen. That makes it a step on from just being sustainable – it’s actually restorative.
It’s good for people too. Greenwave believe it could be a viable option for fishing communities that have lost their livelihoods to overfishing. By switching from fishing to farming, the sea would continue to provide jobs and maintain a way of life, and fish stocks would be gradually rebuilt. Since 90% of the world’s fish stock are under stress in some way, that could be a vital transition for coastal communities.
The downsides? We don’t eat a lot of kelp. Not in Britain at least, though they’re a staple food in many other parts of the world. There’s no reason why we shouldn’t eat more sea vegetables, given how nutritious they are. But it will take some smart marketing to get us there.
Fortunately, there are other uses that could still make sea farming viable on our coasts. Seaweed can be used for biofuel, animal feed, or fertiliser for more land-based farming.
There are others working on similar ideas. Greenwave are distinctive in open-sourcing their techniques, making it possible for anyone to set up in ocean farming. Moules, anyone?