16 Shrimp Culture
An industrialised vannamei shrimp farming model in China In Rizhao, Shandong province, light shaded algae ponds model is creating an impact. By Technical Support Team, Grobest Group Limited
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ince 2012, in the northern part of China, the industrialised farming of turbot was badly impacted due to low market price, disease outbreaks and drop in groundwater levels. Later, as farmers shifted to sea cucumber farming, they also suffered the same fate. Consequently, some of these turbot and sea cucumber farmers decided to renovate their concreate ponds and switch over to industrial farming of the white-leg shrimp Penaeus vannamei. After five to eight years of development, two common farming models have emerged; light shaded ponds with algae and dark shaded ponds using probiotics with water exchange. From our observation, such models have greatly contributed to farming success. In this article, we would like to focus on the basic infrastructure of these light shaded algae ponds.
Concrete ponds
Along the coast, south of Qingdao, the concrete ponds around Rizhao, Weifang and their vicinity are 5m x 5m and 6m x 6m square ponds. Going up north, around Haiyang, Zhushang and the vicinity, these ponds are larger at 10m x 10m and 20m x 20m. There are also smaller rectangular ponds of 3m x 6m and 3m x 7m which have been developed following the sea cucumber ponds in Hebei, Tongying, Yingkou and Dalian areas. Steel frames have been installed above these concrete ponds. In Rizhao and Haiyang areas, clear wrap films are used in two layers or in one layer with vinyl plastic. The overall structure resembles that of shading in a vegetable garden. While in Tongying and Hebei areas, polypropylene sheets are inserted between the steel structures, creating semi-transparent dark shadings.
Dark shaded ponds use probiotics with water exchange
September/October 2020 AQUA Culture Asia Pacific
Heating
Heating of pond water is by various ways: geothermal heat pumps, geothermal wells, gas turbines, biomass boilers as well as aluminum tubes in a central plate and steel with zinc coating. Coal-fired boilers have been phased out as a heating device.
Aeration
These are achieved using root blowers and nanotubes in the smaller ponds and paddlewheel aerators in larger ponds. The target is optimal aeration of 4.0 ppm throughout the culture cycle.
Pond design
Ideally, these should be circular in shape. Otherwise, it would be rectangular externally and circular internally, with a sludge pipe in the centre.
Water conditions
These vary with locations. In Shandong province, farms around Rizhao, Haiyang, Yentai and Weifang areas, use underground water at 10-25ppt salinity. Water is sandfiltered before channeling into the culture ponds. In normal, light shaded farms, the well water is sand filtered prior to use. In order not to disturb the shrimp, the water flow is controlled. Water is only added at 8 am to 3 pm. In the dark shaded ponds, the well water, after sand filtered is directed to boilers and flow into the ponds at 27~28°C. Around Tongying in Hebei province, sea water is used. Usually there are outdoor disinfectant ponds of various sizes, from 1,300m2 to 3,300m2. Water is sand filtered and heated before flowing into the ponds. Since there is no temperature difference, there is no limit on water exchange.
These light shaded ponds have algae, diatoms and chlorella.
In the big ponds, paddle wheel aerators oxygenate ponds.
