The flood pulse and growth of floodplain fish in Bangladesh

The floodplain fisheries associated with the Compartmentalization Pilot Project, Tangail, Bangladesh, were monitored using a traditional length-based fish stock assessment programme from 1992 to 1998. The growth of Colisa fasciatus (Bloch & Schneider) and Channa punctata (Bloch) was significantly higher in years of high floods. Further, the annual yields of Puntius sophore (Hamilton), C. punctata and C. fasciatus were significantly higher in years with high growth rates. The increased growth rate resulted in the presence of two cohorts in the catches during high floods instead of one cohort during years of low flooding. The species studied had relatively short life spans with longevity of 2.4-4.6 years. The majority of fishes did not survive the first year of their lives because of the low survival rate caused by high fishing mortality, which suggests that the fishes in the floodplains of Bangladesh exhibit an annual cycle. Annual fish yields in the flood plains of Bangladesh, appear to be maintained, despite the high fishing effort, by the annual flood pulse providing the nutrient-rich environment needed for the remaining r-strategists to survive.