Tidal bore induced upward shift of marine fish species in Hooghly estuary, India

Abstract

A total of ten different marine/brackish water fish species was recorded at Tribeni, a completely freshwater region located 212 km upstream from the sea in Hooghly estuary just after tidal bore, a natural high wave and high flow regime created during the spring tide around full moon/new moon days. A range of 85 – 179 km upstream shift of recorded marine fish species from their normal distribution range may be attributed to high turbulence, flow, and wave associated with bore tide as there is no sign of saltwater ingress in the Tribeni area as revealed through the analysis of associated environmental parameters. In addition to salinity, such extreme climatic events like tidal bore should also be considered to explain the fish species distribution in a tidal estuary.