Sustainable freshwater aquaculture in the mangrove-dominated Indian Sundarbans

 
P2Porteresia collectionWest Bengal India c University of Calcutta2007

Porteresia collection, West Bengal, India © University of Calcutta, 2007

Objectives

This project examined the protein content of salt marsh grass with a view to developing an eco-friendly, nutritious feed for freshwater prawns. It adapted feed preparation technology to local conditions by using locally sourced floral pulp as the main feed ingredient, and assessed the impact of this floral feed on prawn biomass, survival rate, condition index and feed conversion ratio. The goal of the project was to determine whether floral feed can offer better aquaculture nutrition and cleaner, more eco-friendly prawn farming than commercially available feed.

Background

Aquaculture farmers in the Indian Sundarbans are increasingly using organic fertilizer and feeds for freshwater culture of scampi (Macrobrachium rosenbergii), a species of prawn that commands high export prices. In recent times, interest has grown in the nutritional quality of coastal flora as an alternative to the trash fish and mollusc flesh used in commercially available feeds, which degrade water quality, reducing the survival and growth of prawns. The key elements of this project included developing an alternative feed from salt marsh grass (Porteresia coarctata) to make scampi culture more sustainable and environmentally friendly, and raising awareness among farmers of the importance of maintaining water quality.

Target beneficiaries

Local freshwater aquaculture farmers of the Indian Sundarbans.

Outputs

  • Water quality was tested in experimental scampi ponds using floral feed and the results compared with those from control ponds using commercial meat-based feed.
  • Locally appropriate feed-preparation technology was developed using locally sourced marsh grass pulp as the main feed ingredient.
  • The impact of formulated feed on prawn biomass, survival rate, condition index (length and weight) and feed conversion ratio was investigated.
  • The relationship between protein-rich feed and protein levels in prawn tissue was tested through regular monitoring.

 

Accomplishments and challenges

The project successfully used science to enhance traditional aquaculture practices. By demonstrating improved productivity and pond health from using the new floral feed, the project won support from local prawn farmers. At the same time, the new feed enhanced water quality, which will in turn protect the existing mangrove habitat and help stabilize mudflats. Prawns reared on floral feed also exhibited greater weights and redder colouring (both attributes with high consumer appeal), and grew more quickly than prawns in control ponds.
Demonstrating the increased effectiveness of locally sourced floral feed has motivated aquaculture farmers in the area to adopt the practice on a larger scale. The survival rate of floral-fed prawns is 76%, compared with 70% for prawns fed on commercial meat-based feed. The project also found that using floral feed produces less waste and so helps to improve water quality. The project had the dual benefit of developing an eco-friendly prawn culture practice and creating an alternative livelihood for women through feed preparation and establishment of a nursery of P. coarctata grass to provide raw material. The government of West Bengal has agreed to train local communities in feed production, thus guaranteeing project sustainability.

Challenges

The challenge for this initiative lies in marketing the floral feed product to encourage its uptake by aquaculture farmers regionally and nationally, and to ensure it can compete successfully with commercial feeds.

Contributions to cross-cutting themes

Communications and gender equality

A guide (in Bengali) was developed to create awareness among local communities of scampi and the benefits of rearing them on floral feed. The project provided an alternative livelihood for women in the form of preparing feed and developing a P. coarctata nursery to provide raw feed material.

Lessons Learned

Thanks to intensive participatory testing with local communities and other stakeholders, this small-scale aquaculture initiative was readily adopted and has strong prospects for alleviating poverty, being environmentally sustainable and locally appropriate. Full ownership and participation by beneficiaries and land owners are vital if such scientific exercises are to be sustainable.

Project Facts

Country

Location

Sundarbans, West Bengal, India

Topic

Duration

2nd Dec 2009 to 1st Jan 2011

MFF Grant Amount

US$12,000

Implementing Partner

Dr Abhijit Mitra
Project Leader
Department of Marine Science, Uni-
versity of Calcutta, 35 Ballygaunge Ci
Circular Road, Kolkata 700 019, India
Email: abhijitmitra@hotmail.com

“Commercial feed contains trash fish and shrimp dust as a source of protein. The residual commercial feed degrades water quality by increasing the organic carbon, nutrient load, biochemical and chemical oxygen demand, and total coliform bacteria.”
— DR ABHIJIT MITRA
PROJECT LEADER

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