01 — The basics
Across the world's coasts, one of the oldest forms of aquaculture is quietly becoming one of the most interesting. Growing kelp and other marine algae on ropes in the sea produces food, supplements and materials without the land, fresh water or feed that most farming demands. In Australia, the industry is still young — but interest is building fast.
What is seaweed farming and how does it work?
Seaweed farming, or seaweed aquaculture, is the cultivation of kelp and other macroalgae on ropes or lines anchored in coastal waters. The basic method is simple: young seaweed is seeded onto lines in a hatchery or nursery, those lines are deployed into the sea and held in place by anchors and floats, the seaweed grows out over a season, and a mature crop is then harvested.
What makes it remarkable is the biology. Seaweed is among the fastest-growing organisms on Earth, and it needs no fresh water, no feed and no fertiliser — it draws everything it needs from sunlight and seawater. That means a well-run seaweed farm can produce a substantial crop with a very light input footprint compared with land-based agriculture.
The state of seaweed farming in Australia
Compared with the long-established kelp farming industries of Asia, Australia's sector is still emerging. Production volumes are modest and much of the activity is early-stage or pilot work — but the level of interest, investment and research has grown considerably in recent years.
One distinctly Australian angle has drawn global attention: the cultivation of Asparagopsis, a native red seaweed. Research — including work associated with the CSIRO and companies such as FutureFeed — suggests that adding small amounts of this seaweed to livestock feed can reduce the methane cattle produce. Trials have shown promising results, and it remains an active area of development rather than a settled, at-scale solution. Alongside this feed application, Australian seaweed is also being explored for food, supplements and bio-materials.
- Low inputs
- Needs no fresh water, feed or fertiliser — just sunlight and seawater.
- Fast growth
- Seaweed is among the fastest-growing organisms on the planet.
- Many uses
- Crops span food, supplements, agriculture and feed, and bio-materials.
What seaweed is used for
The appeal of seaweed farming is the breadth of markets a single crop can supply:
- Food and sea-vegetables: seaweeds have long been eaten directly and used as ingredients, and demand for them as foods is growing in Australia.
- Supplements: kelp and seaweed supplements are valued as natural sources of iodine, minerals and other nutrients.
- Agriculture and feed: seaweed is used in soil conditioners and animal feed, including the methane-reducing feed additives now being trialled.
- Bio-materials: seaweed is a feedstock for bio-packaging and other bio-based materials being developed as alternatives to conventional plastics.
The environmental angle
Seaweed farming is often framed as a climate and ocean solution, and there is a genuine case for it — but it deserves a balanced read. Cultivating seaweed can take pressure off wild stocks by supplying material that might otherwise be harvested from natural reefs. And when farming is paired with active restoration, it can directly support reef recovery rather than simply extract from the sea.
That said, seaweed farming is still aquaculture, and like any sea-based food production it must be sited and managed responsibly. Poorly placed farms can affect local habitats, water flow or other marine users. The benefits depend heavily on choosing the right location, the right species and a sensible scale — which is why responsible operators treat siting and management as central, not an afterthought.
Where Ocean Greens fits
For most operators, seaweed farming is purely a crop. Ocean Greens uses it as two things at once: a restoration tool and a commercial engine. The model is a deliberate loop. We clear urchin barrens that have stripped reefs bare, replant native kelp on engineered farm lines to rebuild kelp forests along the Great Southern Reef, then harvest a sustainable share of that seaweed to sell as supplements, foods and bio-materials.
The revenue from those sales is designed to fund the next stretch of restoration — a self-funding loop intended to let reef recovery expand without depending on grants alone. It's part of a wider effort to make rewilding Australia's waters something that can pay for more of itself over time. Ocean Greens is an early-stage company, so the outcomes and figures we describe elsewhere on this site are 2030 targets and projections rather than results already achieved.
Common questions
What is seaweed farming?
The cultivation of kelp and other macroalgae on ropes or lines anchored in coastal waters. Seaweed is seeded young, grown out over a season, then harvested — needing no fresh water, feed or fertiliser.
Is seaweed farming established in Australia?
Not yet at scale. Australia's industry is emerging compared with established producers in Asia, but interest is growing — including notable work on Asparagopsis seaweed as a livestock feed additive.
What is seaweed used for?
Food and sea-vegetables, supplements (iodine and minerals), agriculture and animal feed, and bio-materials such as bio-packaging.
Is seaweed farming good for the environment?
It can be. Well-sited farming takes pressure off wild stocks and, paired with restoration, can support reef recovery — but it must be sited and managed responsibly to avoid local impacts.