Unlike most of the bheries (shallow fish ponds) spread over the Minakhan block in West Bengal’s North 24 Parganas district, the 12 bigha pond of Pintu Das in Chaital village is dotted with trees. Rows of trees form clusters at various places in the pond and occupy the raised earthen embankments, which become slippery after every spell of monsoon rainfall.
A group of experts visiting Chaital village on the eve of the International Day for the Conservation of the Mangrove Ecosystem, observed on July 26, were impressed by the flourishing trees. “In just three years, the tree has outgrown me,” K. Kathiresan, Honorary Professor at Annamalai University, Tamil Nadu, an expert on mangroves, said pointing at a bain tree (Avicennia marina ).
Explaining that the Avicennia is the best suited among mangrove species for plantation in the region, Dr. Kathiresan said the salinity under the root of the Avecinia plant is higher than the salinity in the water and soil, and the plant absorbs salinity from the soil. Other mangrove species with which the shrimp cultivators are experimenting include Heritiera fomes (sundari tree), Nypa fruticans (nipa palm) and Rhizophora mucronata (garjan tree).
As the shrimp farmers calculated the salinity of water at different places in the fish pond, Ravi Shankar Thupalli, an international mangrove management specialist, said that not only the leaf litter from the mangroves but the presence of more trees will invite more birds to the pond, and bird droppings would increase the yield of shrimp.
Both the experts told the shrimp farmers to plant more mangrove trees for dense foliage and high shrimp yield.
About 35 farmers in the Chaital village have turned a leaf in sustainable aquaculture by integrating shrimp cultivation with mangrove plantation. “For the past three years, we are not purchasing fish feed — the leaf litter from the mangroves is turning out to be food for the shrimp,” Mr. Pintu Das said.
Another shrimp farmer, Ashok Das, who has about four bighas of fisheries, agreed that using mangrove leaf litter has helped farmers save money without affecting the yield of shrimp.
For shrimp farmers, the biggest challenge has been a viral infection that hit shrimp yield. Both Mr. Pintu Das and Mr. Ashok Das said that after they started using mangrove leaf litter, there had been no viral infections in the shrimp.
The fish species cultivated by the shrimp farmers in Chaital include Penaeus monodon (tiger prawn), Penaeus indicus (chapra chingri) and Macrobrachium rosenbergii (golda chingri), which bring high economic benefits to farmers along with local fish like parshe and bhangon.
After the interaction, the experts were invited to the house of the fisherfolk, where a young girl performed a song on the sundari tree, which gives Sundarbans its name. Locals emphasised that mangroves are the key to the lives of people in the Sundarbans.
“This is a very good initiative and can be implemented in other parts of the country as well,” Dr. Kathiresan told The Hindu.
Animesh Roy, another fisherman with about 20 years of experience, said the biggest challenge in shrimp cultivation in the Sundarbans was frequent cyclones and high tides during which sea water breached the embankments, resulting in high losses. Mangrove trees with their elaborate root system hold the soil and abate the storm surges in the region dotted with shallow fish ponds, Mr. Roy added.
Conservationists have been stressing the importance of sustainable shrimp cultivation in the ecologically fragile Sundarbans for a long time. Earlier this month, during a national symposium in Kolkata on ‘Building synergies for healthy mangroves and robust value chain around the mangrove ecosystem in Sundarban’, an entire day was dedicated to sustainable aquaculture in the mangrove ecosystem.
The initiative of integrating shrimp cultivation with mangrove plantation was taken up by the Nature Environment and Wildlife Society (NEWS), an NGO working for the protection of natural ecosystems under the SAIME (Sustainable Aquaculture In Mangrove Ecosystem) project started in 2020 and funded by the Government of Germany (BMZ) and the Global Nature Fund.
Prasanta Kumar Biswas, Professor, Food Technology and Biochemical Engineering, Jadavpur University, said that with the nature-based attempts at Chaital, shrimp cultivation in Minakhan was coming full circle. Prof. Biswas, who hails from the region, said aquaculture had begun with paddy cultivation in the region in the 1980s, following which paddy farming was replaced with shrimp cultivation by locals, ignoring traditional methods.
“When we expanded aquaculture in the Sunderbans, it came at the cost of the mangroves as we cleared the mangroves and excluded the plants from fishery farming. Under this initiative, we are going for nature-based solutions and trying to integrate mangroves with fisheries again,” Ajanta Dey, joint secretary of NEWS, said.
