Eco-friendly shrimp farming with ‘biofloc’

High-Density Polyethylene (HDPE)-lined shrimp ponds dot the landscape of Mahendrapalli, a small village on the banks of Pazhayar about 18 km from Kollidam.

Here, Suryakumar Boriah, is silently working on an eco-friendly, disease resistant shrimp farming called biofloc on his vast farm. Biofloc is a beneficial bacterial colony-based culture that keeps other bacterial diseases at bay, making it an ecologically sustainable symbiotic system. Biofloc shrimp farming differs from traditional plankton-based shrimp culture that often keeps farmers on tenterhooks due to the threat of disease outbreak.

Owning the only one-of-its-kind farm in the State, Mr.Suryakumar is one of the very few farmers in the country practising biofloc since 2011.

Zero-water exchange

The zero-water exchange of biofloc makes it eco-friendly. “pH and nitrogen levels in water are the biggest concern in shrimp culture,” says Mr.Suryakumar. The bioflocs keep the pH levels steady and feed on the nitrogen produced by the shrimps. “In conventional farming, nitrogen is flushed out through water exchange every 25-30 days to keep animals stress-free and disease-free. The bioflocs use up the nitrogen and convert it into proteins, for the shrimps,” says Mr. Suryakumar. This cuts down artificial probiotics for the animals. Traditionally, water exchange is often a contention between local land users and shrimp farms.

“The tightly HDP-lined ponds insulate the animals from diseases,” says Govindaraj, manager of Suryakumar’s farm. It costs about Rs.14 lakh per hectare for a biofloc pond, thrice as much as a traditional pond. But the capital investment is out-weighed by the benefits of the system. “There is no dry-out season, and the ponds are crop ready anytime. The HDP linings are intact for five years,” says Mr. Govindaraj. Biofloc cuts down on fish meal as shrimp feed. According to Mr.Suryakumar, the eventual goal is to bring down food conversion ratio to 800 gm of fishmeal to produce 1 kg of shrimp (FCR 0.8:1).

High production

Production per unit area is high in biofloc system. Production per hectare in a conventional pond is 10-15 tonnes, while a biofloc pond gives out 20-30 tonnes.

The stocking density of animals in HDP-lined biofloc pond is twice the density of an ordinary shrimp pond.

Mr. Suryakumar had picked up the system from Yoram Avnimelech, the man known to have founded the technology in Tilapea fish culture. Currently heading the International Working Group on Biofloc Technology, Professor Yoram has referred to Mr. Suryakumar’s innovations in biofloc shrimp culture in his publication.

However, constraints to adopting biofloc remain. This system requires continuous supply of oxygen through aerators, needs capital subsidy from Marine Products Exports Development Authority and demo-farms for exposure and institutional support for farmers, says Mr. Suryakumar.

Besides, Coastal Aquaculture Authority’s regulation on maximum stocking density of ponds, and general excise restrictions on use of molasses for carbon source should be revised for licensed farmers, says Mr.Suryakumar. According to Kandan, Assistant Director, MPEDA, it is a reversal to traditional knowledge. Traditionally moss was allowed to grow in ponds as fish feed. Biofloc draws from the same method. Just as the shrimp sector in the country finds itself on the brink of potential EMS (early mortality syndrome) outbreak, biofloc shrimp ponds ring in a ray of hope; provided there is institutional support for farmers.

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Printable version | Jul 28, 2021 3:42:32 PM | https://www.thehindu.com/news/cities/Tiruchirapalli/ecofriendly-shrimp-farming-with-biofloc/article5656204.ece

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