Food selectivity and reproductive biology of small indigenous fish Indian river shad, Gudusia chapra (Hamilton, 1822) in a large tropical reservoir

Assessment of life history strategies of economically important small indigenous fishes (SIF) which are rich in nutritive values is essential and imperative to artisanal and subsistence small-scale inland fisheries of Indian tropical reservoirs. The present investigation aims to estimate the food selectivity in juveniles and adults, reproductive traits such as sexual maturity, gonadosomatic index, ova diameter, and fecundity of Gudusia chapra from a large impounded ecosystem of India. A total of 668 (Juvenile 129, adult 539) specimens, 37 to 142 mm standard length and 0.89–25.68 g body weight were collected during October 2014–September 2015. The qualitative estimation of the stomach contents revealed herbi-omnivorous feeding behavior of fish. The mean relative gut length (mRGL) of the species was 1.557 ± 0.024 in juveniles and 1.154 ± 0.012 in adults. The sex ratio was 1:1.30 with dominance of females in the population though insignificant. The total length at which 50% individual attain maturity (TL₅₀) was estimated as 80.50 mm based on the logistic curve. The absolute fecundity of the individuals ranged from 749 to15044, and ova diameter ranged from 0.10–2.00 mm. The gonadal indices (GSI, MGSI, and DI) indicated that spawning extended throughout the year with peak reproductive activity in October, March–April, and July (mean absolute fecundity ranged from 4000 to 6000). The present study characterized biological and reproductive traits of G. chapra from a large reservoir ecosystem and demonstrated a new trend of reproductive pattern which will serve as benchmark data for future assessment and management planning of this species in impounded waters. The study also suggested some specific management measures for sustainable exploitation and conservation of small indigenous species.