Beels or floodplain wetlands are low-lying areas along large rivers in India that flood seasonally due to spill over from the rivers. These are valuable fishery resources in India as they provide nutrients, livelihood, and opportunities for rural entrepreneurship . Assam has approximately 3,513 wetlands, which are often the sole source of fish for local underprivileged populations nearby . Notwithstanding the immense potential for beel fishery, very limited scientific effort has been made to evaluate the potential of beels for fish production in Assam, particularly in lower Assam . The Sareswar beel in the Kokrajhar District of Assam, India, is a freshwater beel with immense potential for developing beel fishery in the region. Information on the biodiversity, ecology, and various biotic and abiotic factors affecting them are essential for the conservation and development of sustainable beel fisheries. This study, therefore, evaluated the diversity, abundance and species richness of fish, and the water quality of Sareswar beel.
Samp ling was conducted fortnightly for three consecutive years (2021-24) covering all the seasons viz., premonsoon (March-May), monsoon (June-August), retreating monsoon (September-November) and winter (December-February). Altogether 76 different fish species under 27 families were recorded, indicating a rich diversity of fish species in the beel. Family Cyprinidae recorded the highest number of species (27 species) followed by Bagridae (6), Ambassiade (4), and Channidae (4 ). Nearly 63% of the recorded species were small indigenous fish species (SIFs). The species richness was highest in monsoon (53 species) , and the least during retreating monsoon (44 species). The overall Shannon-Wiener diversity index (H’) was 3.15 , and its value was maximum during premonsoon (H’ = 3.00). Maximum species (86.84%) were found to be ‘Least Concern’ (LC), while five species were ‘Near Threatened’ as per IUCN (2024).
Majority of water quality parameters were found to be in the permiss ible range. Water depth was 129.88-298.72 cm during different seasons, while Secchi depth ranged between 113.92 to 146.45 cm. The mean water temperature range d from 19.99-27.98 ⁰C . The DO and FCO2 ranged between 8.05-8.41 mg/L and 4.06-6.58 mg/L, respectively, while the mean water pH was 6.72-7.82. Results of other water quality parameters were: conductivity 104.39-120.00 μS/cm, total alkalinity 26.95-53.25 mg/L, total hardness 28.97-41.96 mg/L, turbidity 5.93-11.66 NTU, Nitrate-N 4.21-7.09 mg/L, calcium 6.85-13.86 mg/L and fluoride 0.07-0.10 mg/L. Additionally, correlation between fish diversity and water parameters was also observed. Results of this study may be useful for development of beel fishery in the region.
Keywords: Fish diversity , Sareswar beel, small indigenous fish species , water quality.