This year, the ban was till May 31. On Tuesday, fisheries department officials will discuss whether the ban can be extended for a few more months from 2008.

Hilsa, a sea fish, is known to migrate 1,200 km upstream to spawn with the commencement of the south-west monsoon. A mature 30-55-cm-long hilsa lays 0.1-2 million eggs in fresh water and the hatchlings emerge in 23-26 hours. These start their journey to the sea, feeding and growing along the way. It can take up to six months and this is when a baby hilsa or khoka ilish falls easy prey to a fisherman with a small, meshed net.

This practice has led to a ban on the capture of hilsa till the end of May. But now, it seems there is a need to wait for a few more months before the hatchlings can reach the sea. Khoka ilish is normally sold at a lower price.

"A blanket ban may not be possible as this is the time when the adult fish is also available. So, we have to impose a ban on trawling further downstream," said a fishery department official.

Although the import of hilsa from Bangladesh has begun and the going rate is Rs 300-350 per kg, demand for the smaller variety is no less.