A controversial trial to see if Falmouth Harbour can be expanded through dredging has begun today.
The £200,000 trial will measure the potential impact of the work.
Environmentalists fear it will damage marine life, including rare seaweed on the river bed. It's expected to last six months.
Mark Sansom, who is the Falmouth Harbour Master says the work is "vital for the future of the port".
But fisherman David Thomas argues that it "threatens the livelihood of all of the inshore fishing fleet".