Diet composition and seasonality of Chrysochir aurea (Richardson, 1846) along Digha coast, West Bengal, India

Abstract

A pioneering study on food and feeding habits and seasonal variation in diet of Chrysochir aurea was conducted along the Digha coast of West Bengal, India, from October 2021 to September 2022. The analysis involved a total of 562 specimens with lengths ranging from 124 mm to 417 mm that were collected by commercial trawlers. The indices of preponderance and relative importance revealed that the crustaceans dominated the stomach content of C. aurea, followed by fishes, unidentified digested matter and molluscs. Among crustaceans, the important food items recorded were penaeid shrimps, Acetes spp., crabs, Squilla spp., and semi-digested shrimps; among teleosts Secutor spp., Bregmaceros sp., Stolephorus spp., ribbon fish, flatfishes, Coilia spp., and semi-digested fish bodies were recorded; whereas, among molluscs Octopus spp. and Sepia spp. were recorded occasionally. Relative length of gut for both sexes was less than one, indicating C. aurea is a carnivore fish. Males and females had the highest gastro-somatic index during the monsoon (2.716 %) and pre-monsoon (2.856 %) seasons, respectively; whereas, the highest hepato-somatic index (male: 1.134 %, female: 1.080 %) was observed during the monsoon and lowest during the post-monsoon (male: 0.777 %, female: 0.769 %) seasons. Based on the overall vacuity index (31.14 %), C. aurea could be categorized as a ‘relatively edacious feeder’. During the monsoon season, the feeding intensity observed was low compared to the other seasons, as revealed in the stomach fullness index (males: 0.656 %, females: 0.907 %). Cluster analysis performed with seasonal percentage gravimetric values of the prey groups revealed that the similarity of food items between monsoon and post-monsoon varied between 87.5 and 90.0 %, respectively. The current findings would abridge an existing knowledge gap in the feeding biology of C. aurea, and, thus, will aid in fisheries management.