The farmers choice of shrimp culture techniques is influenced by:
- Land, water, power availability and cost
- Transportation and cost
- Credit availability and cost and repayment terms
- Labor availability and cost
- Feed/Fertilizer/Probiotics availability and cost
- National planning regulations & environmental controls
- Import/export costs
- Proximity to existing market
AFT has technical experience with the following shrimp culture techniques:
- Semi-extensive systems
- Intensive systems
- Super intensive systems
- Super intensive nursery systems
- Multi-phase production systems
- Biofloc technology
- Integrated manure denitrification systems.
For all the described shrimp culture systems, AFT highly recommend the use of an Closed Recirculating System (CRS).
Closed Recirculation Systems (CRS)
A closed recirculation system can be used in existing semi-intensive systems and in super-intensive systems. The farming of shrimp in closed recirculation systems involves the installation and operation of a recirculation system for the water being used during the grow-out period. The culture water is continuously re-used and treated in order to regenerate a water quality suitable for the shrimp or fish to grow.
A closed recirculation system can consist out of the following components:
- Culture basin
- Solids filter removing suspended particles
- Denitrification reduction of nitrate products and stabilize the ph and alkalinity
- Reservoir & Bio filter, nitrification removing organic matter and ammonia products
- Sludge removal & discharge
The choise of system depends on the specie that is cultured but may consits out of: a hybrid system utilizing a combination of heterotrophic bacterial flocs and clear water supported by probiotics, also called SEMI-BIOFLOC.
A CRS System offers the following advantages
- Higher biosecurity against shrimp diseases and parasites, incoming water is disinfected and treated
- Higher yield, (more shrimp per volume water, higher grow rates, lower FCR, higher survival rates)
- Smaller area needed for your production
- Less water needed from a water source or sea
- Effluent water can be reduced to a minimum
- Location and climate independent
- Zero water exchange during culture
- Possibility of partial harvests, sales of fresh or live shrimp, fish for local market
- Full traceble end product
- The system is relatively advanced compared with traditional farming systems. It need a back up power supply and alarm systems
- Workers need to be trained
- The system is relatively expensive to set up, and requires a minimum production capacity for an economical operation
A Biofloc floccule is a miniature, loosely held collection of materials (uneaten feed, faeces, detritus, and other particles) and attached organisms (bacteria, algae, protozoea, rotifers, copepods, nematodes and other micro-organisms). They are the basis of the food chain in water. The nutritional value of organisms associated with bioflocs has been proven, even for larval stages of shrimp.
At intensive aeration the faeces of shrimp are assimilated by bacteria. These bacteria form colonies and take pollutants out of the water (ammonia) and convert them into proteins
Shrimp consume these bioflocs actively or passively. We thus obtain recycling of feed (similar to nature). Bioflocs have a gross size of about 0,1 to 3 mm.
Integrated manure denitrification System
The integrated manure denitrification system is fed with the concentrated waste flow from a shrimp or fish farm system containing dissolved and particulate faecal organic waste, bacterial flocs and inorganic compounds. In the sludge of the bioreactor the faecal particulate carbonaceous waste is digested by the denitrifying bacteria and results in: (1) the production of bacterial biomass (2)reduction of nitrate into nitrogen gas, production carbon dioxide (3) production of alkalinity (4) miniralization and reduction of the sludge. The particulate waste in the sludge bed serves also as media for the denitrifying bacteria to grow on. Sludge leaves the bioreactor through a patented filtration unit, and can be discharged from system when necessary.