The seaweed industry is recognised by Indonesia's national government as one that supports tens of thousands of coastal households and has potential for modernisation and expansion. They are the world’s largest producer of carrageenan seaweeds and the industry contributes to the livelihoods of at least 66,000 generally low-income coastal households.
At the moment mainly carrageenan seaweeds are harvested, it’s use as a gelling or thickening agent in food processing, cosmetics and other applications. Currently Indonesia is a significant global exporter of this seaweed that is dried but otherwise minimally processed. South Sulawesi is the largest producer of the seaweed known locally as Sulsel.
As we have been sailing around we have been intrigued by the way they are able to grow and harvest 450,000 ton (dry weight) per year. It is a staggering amount of wet seaweed that is sustainably cultivated and harvested each year, that’s two-thirds of the global supply.
The farmers use a longline system where light rope is strung between lots of plastic water bottles. They are floated out in lines, and anchored to the seabed at each end, not unlike pearl farming. Most of the work around seaweed farming is done by the entire household.
Once grown, the seaweed must be harvested and brought to shore, removed from longlines, separated into cuttings for use in propagating for a new farming cycle (and the remainder for drying), the longlines cleaned, and then seaweed cuttings reattached, longlines returned to the sea and planted. This generally must occur on the same day since seaweed cuttings are highly perishable and cannot be out of the ocean for extended periods of time.
The drying process once the seaweed is spread out is simply done by nature. On bamboo rafts or outspread on netting placed on the ground, Mother Nature (the sun) takes care of the drying process. Then it is bound up into bundles, ready for export.
Using plastic bottles is a cost effective way to float seaweed long lines, this is seen by the locals as a good solution to the many water bottles that would normally be thrown away that they don’t have a recycling system for.
But together with the synthetic line used they might also degrade in water and contribute to more water-based plastic pollution. A study is currently being conducted and the inItial results suggest that on-farm bottle degradation is less significant than the post-use disposal plastics in marine environments. Prioritising end-of-life management of plastic waste is the important first step to reducing marine pollution associated with seaweed farming.
