Productivity of a seaweed farm is measured by the number of harvests a year and the biomass increase in weight (yield). Some seaweeds are harvested fully, meaning the entire biomass is removed from the site, while others are harvested partially, with some biomass remaining for further grow out. Yield is often stated in kilograms (kg) per metre (m) of line, since metric tonnes (MT) per hectare (ha) is not always a common measure among farmers.
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The number of harvests that can be done is highly dependent on the season.
In Indonesia, April to October (dry season) is the most productive time to cultivate Gracilaria in brackish water ponds. During those months, farmers report a daily growth rate of 4 –5%. During the transition of dry to rainy season, farmers report that Gracilaria grows better with the long line method in shallow areas at sea.
In China, Gracilaria is cultivated all year around. From April to May in South China and from May to October in North China. During the most productive months, when Gracilaria grows fast, the crop can be harvested after only 20 days.
Gracilaria can be harvested at any size. Usually farmers wait between 40 and 60 days before they harvest. A harvest conducted at 60 days will get high yield and gel strength.
In scattered pond culture, harvesting is done by picking up the seaweed and bringing it to shore, since farmers can walk in the shallow ponds. Depending on the amount of biomass, a boat is utilised for transportation to shore.