The most important aspect in developing a potentially productive seaweed farm is site selection. Farmers essentially look for good water motion that can replenish nutrients, keep the seaweed clean and prevent extreme fluctuation of temperature, salinity, pH and dissolved gasses. At the same time the farm shouldn’t be too exposed to strong winds, waves and currents. The exposure, location, water depths and substrate beneath the farm will determine the farm design and cultivation method applied.
Explore Site Selection by Species
Gracilaria can either be cultivated in land-based ponds or at sea. Sheltered environments like bays, estuaries, or river mouths are suitable if they have sufficient water circulation.
In Indonesia, pond-based culture of Gracilaria is more common. Gracilaria changii, a common species, grows well at temperatures between 25ºC and 30ºC, and salinity in the range of 20 – 30 ppt.
The main production areas for Gracilaria farming in ponds are East Java (Sidoarjo), Central Java (Brebes) and West Java (Karawang). The species, Gracilaria changii and Gracilaria gigas have been cultivated in the shallow sea water since 2003 in Takalar, South Sulawesi.
In China, the species Gracilariopsis lemaformis is most commonly farmed and the cultivation takes place at sea. The optimal conditions for its growth are water temperatures around 15°C and salinity levels below 33 ppt. During the winter months, Gracilaria farming takes place in Southern China (between October and May) and when waters are getting warmer and farm space available in Northern China (because Saccharina and Undaria is harvested), Gracilaria will be farmed in Shandong region between May and October).
In Indonesia many traditional brackish water ponds for shrimp farming are today used for Gracilaria farming. It’s due to the shrimp productivity decrease or white spot disease caused by white spot syndrome virus, that these ponds are not used for shrimp farming anymore.
Most Gracilaria species that have high economic value grow in warm to temperate waters between 15-32°C and can tolerate salinity in the range of 15 to 50 ppt.
Ponds are generally located in protected areas, not exposed to strong prevailing winds, and near sources of both freshwater and seawater, to allow the possibility of optimising salinity. They should have a degree of water exchange at least every 3 days during high tide.
A concession or licence to farm is mandatory in China and granted through application via the local government. Gracilaria is often farmed as fresh feedstock for Abalone farms and located in close proximity to them.
In Indonesia, corporate farmers should apply for a permit (concession) from the Ministry of Marine Affairs and Fisheries (MOMAF). Smallholder farmers are not required to have a permit (concession) from the MOMAF.