Biofloc method for Vannamei farming

Description

GS PAPER II: Conservation, environmental pollution and degradation, environmental impact assessment.

Context: The Kerala University of Fisheries and Ocean Studies (Kufos) is looking to deploy the biofloc method to farm Vannamei shrimp even as COVID-19 restrictions and job losses are turning more and more people to self-employment in agriculture and allied activities.

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It has found acceptance among aquaculturists with the Department of Fisheries offering support for the programme.
The fish that is now being widely cultivated using the technology is the genetically-modified farmed tilapia (GIFT).
Such ventures can be turned into economically-remunerative ones for farmers by switching the candidate species to Vannamei shrimp.

Biofloc technology

It is an intensive aquaculture system and is considered to hold an advantage over conventional systems, as the normally harmful waste produced in conventional aquaculture can be turned into feed for fish.
Those with limited land area could take up fish culture using the technology.
The exotic whiteleg shrimps are native to the Eastern Pacific Ocean and have been found to be suited to the brackish water conditions in Kerala.
Extensive culture of Vannamei has been undertaken in Andhra Pradesh, West Bengal, Orissa, and Tamil Nadu, among other coastal States.

Biofloc system was developed to improve the environmental control over the aquatic animal production.
In aquaculture, the strong influential factors are the feed cost (accounting to 60% of the total production cost) and most limiting factor is the water/land availability.
Biofloc system is a wastewater treatment which has gained vital importance as an approach in aquaculture.
The principle of this technique is the generation of nitrogen cycle by maintaining higher C: N ratio through stimulating heterotrophic microbial growth, which assimilates the nitrogenous waste that can be exploited by the cultured spices as a feed.
The biofloc technology is not only effective in treating the waste but also grants nutrition to the aquatic animal.
The higher C : N is maintained through the addition of carbohydrate source (molasses) and the water quality is improved through the production of high quality single cell microbial protein.
In such condition, dense microorganisms develop and function both as bioreactor controlling water quality and protein food source.
The biofloc technology has been implemented in shrimp farming due to its bottom dwelling habit and resistance to environmental changes.