Impact of River Salinity on Fish Diversity i n the South-West Coastal Region of Bangladesh

ABSTRACT Saline water intrusion is a major problem and conflicting issue in south-west coastal region of Bangladesh. Thepresent study provides an asses sment of changes of fish div ersity with the cha nges of salinity lev el i n the nearby riverover the last thirty years . This study is carried out through semi-structured questionnaire survey i n selected villagesof different salinit y prone areas such as high s aline zone and moderate saline zone , namely Paikgacha a nd Rampal,respectively. The increased salinity has negative impact on fish diversity in this region. Local people’s perception,experts’ judgment was used in detecting decreasing of fish diversity with increasing in river salinity. The study hasrevealed that in Paikgacha, the salinity varies approximately within the range from 20,000 to 45,000 micromhosand in Rampa l it is from 10,000 to 30,000 micro-mhos. D ue to in crea sed sa linity, t he fish spec ies in Paikgacha andRampal have been reduced from 29 to 12 and 24 to 19 species respectively during the period 1975-2005.Dominancy of very few sali nity tolerant species is increasing in both areas but it is more visible in Paikgacha thanRampal.