Fifteen robbers were also arrested during the drive to rescue the abducted on Friday morning.
According to Commander Lt Borhan of Coast Guard in Hatia, 20 boatmen and 20 fishermen were abducted by the robbers from Kutubdia in Monpura two days ago.
On receiving the information, the Coast Guard conducted the drive, and found the boatmen, fishermen and the robbers in the Char Gangi area.
Six machetes and 13 bullets were also recovered from the kidnappers.
Lt Borhan also said that eight more firearms were cast into the river by the pirates after they had sensed the presence of authorities.
"These will be recovered soon," he added.