The culture of Litopenaeus vannamei has been fairly popular since the late 20th century. Due to its intensification, many farmers are able to turn a quick profit with the culture of the shrimp. However, the production of the species is limited by its susceptibility to various diseases, including the notorious white spot syndrome, vibrio infection, and many more. It is not uncommon for farmers to profit for the 1-2 batch of culture, just to lose all their profits & capital during subsequent batches due to diseases. The popularity in culturing Litopenaeus vannamei has also resulted in the spread of infectious diseases, due to effluent discharge from infected farms. These pressing issues have driven the need for farmers to adopt technologies that could protect them from these devastating losses. One of the promising technologies have been gaining popularity with existing shrimp farmers is the Biofloc technology. In this post, we will be sharing how bioflocs might be a potential game-changer in the shrimp industry.
In open systems, water quality is primarily maintained by water exchanges that is convenient but compromises biosecurity. A practical approach in maintaining good water quality in ponds without compromising biosecurity is the adoption of Biofloc technology. Biofloc technology system originates from the activated sludge wastewater treatment system. It relies on the development of the heterotrophic microbial community to maintain water quality without the need for water exchange or biofilters used in recirculating aquaculture systems. Reducing the need for water exchange minimizes the risk of pathogens entering your pond system via incoming water. Furthermore, farms can be positioned inland, away from the coastal areas as zero water exchange can be achieved. Indoor shrimp farm ran on biofloc systems are often cheaper to set up then recirculating aquaculture systems. However, maintaining the biofloc systems requires detailed technical know-how and experience. Indoor shrimp farming ran with Biofloc systems help in ensuring a fully bio-secured operations protecting even against birds that will potentially bring pathogen in open ponds.
In traditional open system ponds, feed cost typically accounts for 50-60% of operating cost. The amino acid profile and digestibility of fish meal make it an ideal choice in aquaculture feed formulation. Fish meal prices have increased by 47% from 2009 to 2019 (with an annualized rate of 3.9%). Many have resorted to exploring alternatives protein sources like soybean, meat and bone meal as a fish protein replacement to reduce cost. Biofloc technology have shown promising commercial results in reducing feed cost in traditional ponds systems. Due to the assimilation of inorganic nitrogen of the heterotrophic bacteria, biofloc systems produce large amount of microbial protein. Under the right conditions, these bacterial aggregates together forming flocculation that traps other debris or particulate. Flocculation that have sufficient mass will settle and made available to the culture animal as an additional food supplement. In short, biofloc technology is able perform an in-situ conversion of waste into additional protein source available to shrimp. Commercial shrimp farms operating on biofloc technology have reported FCR values of 1.25 with yields of 20 ton/ha each cycle (Avnimelech, 2012), while traditional farms reporting values of 1.68. These aggregate of bacteria often contains good bacteria that can colonize the gut of shrimp having effects of a good probiotics. Accumulation in bacterial storage compound poly-β-hydroxybutyrate (PHB) that protects the cultured species from bacterial infections (De Schryver et. al., 2010). Up to 18% of the biofloc dry matter is reported to contain PHB which could be depolymerized in the gut of shrimps have shown to prevent vibriosis (Crab, 2010).
Recent findings suggest that biofloc or its by-products can regulate the virulence of Vibrio spp (Defoirdt et. al., 2008). Survival rates for shrimp cultured in biofloc technology are significantly higher than those cultured in recirculating aquaculture systems (Kim et. al., 2014). Biofloc produces quorum sensing antagonists or production of signal molecule-degrading enzymes that disrupt luminescent vibriosis. Bioflocs also triggers the nonspecific immune activity of shrimp, providing a warning sign on the impending diseases.
The benefits of biofloc on the shrimp cultures have led to the further intensification of the culture of Litopenaeus vannamei. Farmers previously avoided high intensification due to the risk involved, and now biofloc serves as a method to hedge against diseases.
In general, biofloc remains a viable technology for both indoor and open pond system. The is a potential game-changer for the industry, and many farms are rushing to adopt this novel technology.