Impact of fish stock enhancement on fish yield of floodplain wetlands in different agro-climatic zones of Assam, India

Floodplain wetlands located in Ganga-Brahmaputra basin are some of the major inland fisheries resources of India with substantial resource size of 554,213 ha. These resources are amenable to capture fisheries and fisheries enhancement. The Guwahati Regional Centre of Indian Council of Agricultural Research-Central Institute of Fisheries Research Institute, Barrackpore, West Bengal, India has developed protocols for scientific fish stock enhancement (through supplementary stocking) for floodplain wetlands (beels) of Assam. These enhancements aim to increase fish yield based on extensive field studies in the beels of the state during 2007–12. In order to assess the impact of fish stock enhancement following the Institute's guidelines, data on fish production of 183 beels under the administrative control of Assam Fisheries Development Corporation Ltd., Guwahati, India were collected and analysed for the period from 2007–08 to 2016–17. The data were analysed for two periods of 5 years each (2007–08 to 2011–12: period-I and 2012–13 to 2016–17: period-II) for unstocked beels (that are not subjected to supplementary stocking, thereby representing capture fisheries) and stocked beels (where supplementary stocking with Indian major and minor carps for fish stock enhancement is practised) in reference to different agro-climatic zones of Assam. The average fish yield from unstocked beels (96 no.) was 156.6kg ha-1yr-1 during period-I, which increased to 206.4kg ha-1yr-1 during period-II, showing an increase of 31.8% over the five-year period. As much as 47.5% of the beels (87 no.) of the state are now subjected to supplementary stocking for fish stock enhancement. The average fish yield rate of stocked beels was 258.5kg ha-1yr-1 during period-I, which increased to 455.2kg ha-1yr-1 during period-II. Thus, average fish yield rates increased as much as 76.1% over the five year periods in stocked beels showing that supplementary stocking resulted in significant enhancement of fish production from the beels of Assam after the Institute's intervention.