Compositional trends of fisheries in the River Ganges, India

Monthly surveys of local fisheries from five principal landing sites on the River Ganges at Bhagalpur, India, were conducted from 2001 to 2007. Fishes of a range of sizes with mostly periodic-type life-history strategies, including many catfishes and carps, dominated the catch. Average annual yield (total mean monthly catch in units of biomass) was highly variable but trended downward during the study. Statistical ordination revealed associations between assemblage composition and hydrological seasons. Overall yields in this reach of the River Ganges tended to be greatest when the annual flood pulse was sustained longer. Patterns of average stock yields and inter-annual variability of yields were associated with species life-history strategies, with the most abundant and least variable species having periodic-type strategies of seasonal spawning, high fecundity, small eggs and no parental care. Although not appearing to have declined precipitously during the study, many stocks in this stretch of the River Ganges, including those of the largest and most valuable species, nonetheless seemed to remain below historical yield levels because of multiple impacts, including chronic intense fishing and other anthropogenic impacts.