Food, feed and fuel: global seaweed industry could reduce land needed for farming by 110m hectares, study finds

An area of ocean almost the size of Australia could support commercial seaweed farming around the world, providing food for humans, feed supplements for cattle, and alternative fuels, according to new research.

But the authors of the research said there are a range of potential negative impacts on marine life that will need to be balanced with the benefits of a global seaweed farming industry.

The study looked at 34 seaweed species and where they could feasibly grow and then narrowed this down to places with calm enough waters and close enough to populations where farms could be established.

About 650m hectares (1,606 acres) was identified as plausible for seaweed farming, with the largest areas in Indonesia and Australia which both have large ocean regions under their economic control.

One of the biggest benefits, the study said, would be the cultivation and use of red Asparagopsis as a cattle feed supplement that has been shown to result in drastically lower methane emissions from cows. One supplement based on the seaweed reportedly went on commercial sale to farmers in Australia last year.

Spillias said introducing more seaweed into human diets could also deliver benefits. In parts of Asia, seaweed makes up 2% of diets, but scaling this up to 10% globally could spare 110m hectares of land currently used for growing food.

A review in 2019 of the risks of expanding seaweed farming in Europe highlighted concerns farms could upset the balance of marine ecosystems and could alter the way water around coastlines moves.

He said if there was a widescale push globally for seaweed farming, there could be social implications.