Mamata said at Nagrakata in Jalpaiguri district that the losses occurred owing to rainwater flowing down from Bhutan through various rivers.
India has exempted Bangladeshi exports to Nepal and Bhutan as such trade facilitation is mandatory for landlocked countries under the framework of provisions of the World Trade Organisation (WTO).
The two sides are expected to ink an agreement on interim sharing of water of the Kushiyara river during Hasina's visit.
Bangladeshi Prime Minister Sheikh Hasina arrived in New Delhi on Monday on a four-day visit to hold talks with his Indian counterpart Narendra Modi following which the two sides are likely to ink pacts in key areas, including defence, trade and river water sharing.
The meeting was scheduled to be held in December, 2003, but was put back repeatedly although it is supposed to meet twice a year.
Bangladesh fears severe consequences for the country if India implements the project.