The giant river catfish Sperata seenghala has huge demand in South Asian countries due to its low number of intramuscular bones and nutritive value. However, the culture practises for this fish have not been standardized and the current demand for this fish is being met by capture fisheries only. Unregulated and indiscriminate fishing would lead overexploitation of fish stocks subsequently stock depletion. Genetic diversity between populations would give insight about population structure and demography. In the present study, S. seenghala stocks from three rivers, namely Ganga, Brahmaputra and Mahanadi were characterized using cytochrome b gene and D-loop region. Moderate to high haplotype diversity and low nucleotide diversity values were observed in all populations. Analysis of molecular variance and pairwise F values showed significant genetic differentiation among populations. Patterns of diversity, haplotype networks and mismatch distribution strongly suggest a historical influence on the genetic structure of S. seenghala populations. S. seenghala stocks from these three rivers are genetically distinct units and management measures should be formulated separately for each population.
Pen culture for in situ raising of stocking material was conducted in Sareni Jheel, located in the Rae Bareli District of Uttar Pradesh. Sareni Jheel, being rich in organic carbon (4.5%) and nutrients, higher values of silt (29%) and clay (15%) were recorded. Rich oxygen levels, alkaline pH, high organic matter, moderate to high chemical parameters suggested moderately productive nature of this wetland. Pen with high-density polyethylene (HDPE) net was installed in an area of 0.1378 ha and stocked with advanced fry of the Indian major carps, rohu Labeo rohita and catla Catla catla in the ratio of 1:1 @ 25 nos. m-2. No significant changes in water quality parameters were noticed within and outside the installed pen. Mean weight at stocking of rohu and catla was 2.88±1.41 g and 2.1±1.16 g, which increased to 57.2±13.84 g and 67.38±25.79 g respectively, in 120 days. The average feed conversion ratio (FCR) recorded was 1.08 with overall survivability of 69.52% in rohu and 74.74% in catla. Benefit-cost ratio and return on investment were calculated as 1.69 and 0.69, respectively. Intervention through pen culture resulted in the increase in fish productivity of Sareni Jheel from 310 to 833 kg ha-1.
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