Exploring polyculture of small indigenous fishes with major carps in pens as a climate-resilient adaptation strategy for northeastern wetlands of India

Pen aquaculture technology, a low-cost aquaculture system for floodplain wetlands of India, was evaluated through a pilot study as an alternative livelihood for increasing adaptive capacity under changing climatic scenario. Five pens (100 m2 area each) were constructed in a floodplain wetland and provisions were made to adjust heights during the monsoon to prevent escapement of fish due to flooding to make it climate-smart adaptation system. Feasibility of culturing high-value locally preferred small indigenous fishes (SIFs), viz. Amblypharyngodon mola, Gudusia chapra and Puntius sophore, along with Indian major carps (IMC) was assessed. Five different species combinations were tested, i.e. P1 (IMC only), P2 (IMC + A. mola @ 30 no./m2), P3 (IMC + G. chapra @ 20 no./m2), P4 (IMC + P. sophore @ 20 no./m2) and P5 (IMC + all three SIFs @ 1/3 of stocking density of each species). The IMC (Labeo catla, L. rohita and Cirrhinus mrigala) were stocked @ 3 no./m2 in all the pens. After 5 months, highest net fish production was obtained from P2 (124.86 kg/pen) followed by P3 (120.19 kg/pen), P5 (105.15 kg/pen), P1 (89.91 kg/pen) and P4 (87.38 kg/pen). The range of water quality parameters recorded during the experimental period was in favourable concentration for fish culture. Economic feasibility analysis of the pen culture operation indicated that culturing IMC with G. chapra or A. mola was more profitable compared to other combinations. The study also showed successful natural recruitment of all the three SIFs in pens indicating that they could breed and continue to support their fishery unlike large carps. With successful culture of fish during flood season, encouraging growth of carps and recruitment of SIFs in pens, it emerged as a potentially effective climate-resilient system which could enhance income and livelihood of the fishers besides providing nutritional security in developing countries.