Four fishermen were arrested by CISF personnel for entering the Paradip Port harbour on Saturday. The fishermen were handed over to the Marine police station at Paradip. Reports said the fishermen entered into the port harbour as their fishing trawler went out of operation in mid sea. They reached at port harbour swimming across seawater, but the security CISF personnel who were present at the site picked them up as the harbour area falls under high-security zone.