Around a dozen fishing boats have blocked the port in the northern French town this morning, which is stopping ferries from leaving and entering the popular port.
Protestors set out on a small flotilla of fishing boat at dawn from Boulogne and others are expected to join from Dunkirk.
P&O Ferries Freight said on Twitter: “The Port of Calais is closed due to a French fisherman blockade. Currently no ship movements in the port.”
A Calais port spokeswoman said negotiations are underway and that port authorities expected the blockade would be lifted by midday.
French fisherman Stephane Pinto said the fishermen are protesting against losses they have because some countries use electrified fishing nets.
Mr Pinto said: “We’re at our wits ends. We feel abandoned.”
Calais is France’s busiest passenger port and a major entry point to Europe for British goods.
Ferries will not be able sail to Dover from Calais as the fishermen stage their industrial action.
Some two million lorries, tens of thousands of coaches and 10 million passengers pass through Calais every year.
Adrien Boussemart wrote on Twitter: “At the moment, at the port of #Calais, we look at the blockage in the distance. These are the little white dots.”
There are 84 Dutch vessels that fish with electrified nets in the South of the North Sea, according to French media.
In January, the European Parliament called for a ban on this practice in the EU, but the fishermen are concerned that the European Commission will overrule this and keep on allowing it.
According to the ecologist Yannick Jabot, electric fishing “decimates the fish, sacrifices the fishermen and decertifies our coastal territories”.
Another French fisherman told Le Parisien: “Electric fishing is a method deemed destructive for the environment.
“Today, because of this practice, some fish species have virtually disappeared.”
According to P&O, two car ferries are waiting in Dover and there are two others in Calais.
Pulse fishing uses electrodes attached to nets to send electrical signal close to the surface of the seabed, driving some fish to move into the nets.
The European Parliament on January 16 voted in favour of banning commercial pulse fishing. Opponents say it is tantamount to putting a taser gun in the water.
Supporters, including The Netherlands which has issued permits to about 80 of its trawlers, say the technique reduces unwanted bycatch and avoids ploughing nets along the seabed.
The European Parliament vote was advisory but means the issue will now be debated with the European Commission and members states and could lead to legislation.