The cultivation method and farm design – which are highly influenced by the individual site conditions – determine what type of equipment is needed on the seaweed farm. Anchors, ropes, culture lines and floats are essential equipment for all cultivation taking place at sea.The material the farmer chooses for each will not only depend on the site conditions, but also on the price and availability of equipment.
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In the past, bamboo frames were used to grow Pyropia in the mud flats and in the 1970s nets started to be used. Today, Pyropia nets are supported on poles or floating systems, depending on the water column depths. There are three popular cultivation methods:
Fixed net cultivation – This method is most suited for the intertidal zones of the Yellow Sea. At sites with lower water depths, the fixed net method or ‘pole’ method is preferred, as it naturally exposes the nets to air at low tide. This method is limited to the shallow sites on a coastline.
Semi floating net cultivation –Can be placed further away from shore where tidal range and depth is greater (7-8 m). Semi-floating systems are a combination of the fixed and floating system, where at high tide the nets float on the sea surface and during low tide the system stands on land.
Floating (turnover) net cultivation – This method can be used further offshore at water depths up to 15 m. Unlike the above methods, the nets won’t be above the water through tide cycles – farmers need to overturn the raft manually when necessary.
Based on tidal phenomenon over the intertidal zones, when the water level is rising the nets with the seaweed are submerged under the water and the water movement should wash the seaweed and remove any foreign material. When the nets uncover from the water at low tide, the sunshine dries of the filamentous algae or other materials to keep the Pyropia clean.
Farm designs are highly dependent on the location's characteristics
The size of each net and unit of measurement differs not only between countries and culture method, but even between farms in the same region.
In South Korea for example, the nets are called a “Gimbal” and the unit size of 10-15 Gimbals connected is called a ‘chaek’. Thus one chaek in South Korea is generally between 2 to 2.5m in width and 40 to 100m in length.