Exploring the reproductive features of Clupisoma garua from Ganges River, Bangladesh: insights into eco-climatic factors for sustainable management and advancements in aquaculture practices.

ABSTRACT

The Garua bacha, Clupisoma garua, holds considerable commercial and nutritional significance as a fish species. This study investigates the relationships between GSI (gonadosomatic index) and eco-climatic conditions, and provides comprehensive insights into several facets of reproduction, such as size at first sexual maturity (Lm), spawning season, peak spawning period, and proposes sustainable management strategies for C. garua in the Ganges River, northwestern, Bangladesh. Since January to December 2017, 570 female individuals have been gathered from the Ganges River using cast nets, gill nets, and square lift nets on a monthly basis. The total length (TL) of the specimens varied from 3.90 to 26.30 cm. Lm was estimated as 14.30 cm based on the results of the TL vs. GSI, MGSI (modified gonadosomatic index), DI (Dobriyal index), 14.00 cm through TL-FL regressions, and 15.18 cm depending on Lmax for this species. Furthermore, the spawning period was observed from May to August, peaking in June and July, based on greater GSI, MGSI, and DI values. Throughout the peak spawning season, there was not a significant differ from a value of 100 in the relative weight (WR) of the female species. During the spawning season, a substantial association between temperature and GSI (p = 0.0038); rainfall and GSI (p = 0.0043); DO and GSI (p = 0.0043); pH and GSI (p = 0.0002); and alkalinity and GSI (p = 0.0001) was detected. Analyzing a 55-year data series (1964-2018), it became clear that an increase in average air temperature of 0.0289 °C and a decrease in rainfall of 2.988 mm per year might possibly delay the spawning season of this species. As a consequence, the results of this study provide crucial information for developing management strategies to safeguard C. garua populations in the Ganges River and its adjacent ecosystems.