Shrimp Culture-Innovation
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Securing the shrimp nursery with water recirculation system By Henry Cuong, Truong Ngoc Thao, Phong Chau and Van Thi Thai Nguyen
View of the BIOSIPEC model in ADM’s R&D centre in South Vietnam.
O
ver the last decade, as shrimp farmers continue to face increasing pressure from several diseases such as white spot syndrome virus (WSSV), early mortality syndrome or acute hepatopancreatic necrosis disease (EMS/AHPND) and white faeces syndrome (WFS), many of them started to add a nursery stage in their production system. The initial purpose of this nursery stage is to maintain post larvae in the best culture conditions for 3 to 4 weeks prior to the transfer to exposed grow-out ponds, where environmental conditions can be very challenging and unpredictable. More than 5 years ago, ADM developed the BIOSIPEC or Biosecurity Intensive Production Environmental Control model. This is an innovative shrimp farming model aimed at reducing water exchange, thanks to a recirculation pond that serves as a huge biofilter to manage waste and keep optimal conditions for the sensitive nursery stage (Table 1).
Figure 1. Schematic representation of the nursery system with the use of recirculation pond.
Today, the flow-through system is the main option for farmers in Asia. However, good water quality resources are scarce in Asia, especially with fluctuating water quality conditions brought about by rainy seasons and frequent disease outbreaks. Therefore, reusing water from a recirculation pond is a sensible way to reduce water usage and limit the risk of pathogenic infections from the external environment.
The recirculation model has three main parts, namely the recirculation pond, the nursery tanks and the wastewater pond as shown in Figure 1. The wastewater pond is both a place to accumulate suspended solids and reduce levels of toxic wastes (NH3, NO2) and pathogenic bacteria (Vibrio spp.). 1
BIOSIPEC WATER EXCHANGE system
Table 1. A comparison between a system with water exchange only and the total water recirculation model in the Biosipec system.
RECIRCULATION pond system
Nursery tank
BIOFILTER tank system
Nursery tank
BIOFLOC system
Nursery tank
Nursery tank
Waste management Recirculation pond
*Blue arrow: inflow of clean water *Black arrow: outflow of water effluent
§ Applicable conditions
§ §
Allows water a single pass through Areas have favourable water resources Water exchange rate : 12-15 times
§ § §
Water circulation with recirculating pond Adapted to areas with limited water supplies Areas are under high disease burden
Biofilter tank
§ §
§
Water circulation with biofilter tank Adapted to areas of extremely limited water supplies Needs high technical skills
§
§
Zero water exchange, waste is kept in water column by strong aeration Require very high technical skills and experience
