CONTROLLING floods in the plains is laudable, but it is not a harmless activity as far as near-shore fish are concerned. Almost all fish-harvesting in Bangladesh is near the shore. All the dams, culverts, embankments and river closures installed in Bangladesh to protect 3 million, flood-prone hectares, have led to a considerable decline in fish harvest, according to a study done by the University of Chittagong.

"This happens because of the obstruction to the natural migration of fish from fresh water to brackish water habitats and vice versa, for breeding and feeding," explained M J U Chowdhury, head of the university's marine science institute.

The reduced flow of rivers is also destroying mangroves in the country. Chowdhury estimates about 45 per cent of the Khulna mangrove forest was destroyed between 1959 and 1983. His studies also indicate mangrove destruction in Cox's Bazar because of increased shrimp farming.

The increase in tiger shrimp farming also has led to widespread destruction of other shrimp and finfish species.