LILLE, France (Reuters) - French fishermen blockaded Calais throughout Thursday, halting shipping movements at France’s busiest passenger port and a major entry point to Europe for British goods, in protest at losses inflicted by the practice of electric pulse fishing.

French fishermen block the locks of the port with their trawlers, as they protest the practice of electric pulse fishing, in Boulogne-sur-Mer, France, January 25, 2018. REUTERS/Pascal Rossignol

A flotilla of fishing vessels set out at dawn from nearby Boulogne, the biggest fishing port, and blocked the narrow shipping channel into Calais, said fisherman Stephane Pinto.

A spokeswoman for the port said the fishermen’s protest ended at about 1600 GMT though it would take several hours to clear a backlog of traffic.

“It is utterly unacceptable that a small number of individuals have been allowed to bring to a standstill a port on which thousands of businesses and tourists rely every day,” Janette Bell, the chief executive of P&O Ferries, said in a statement.

Some two million lorries, tens of thousands of coaches and 10 million passengers pass through Calais every year, Jean-Marc Puissesseau, the port’s general manager, told Reuters earlier this month as he detailed the risks to trade flows from Brexit.

“After sitting on Dover dock for 6 hours this morning our vehicle was finally loaded onto a ferry ... now circling outside Calais for hours ... why did this boat sail if there was no access to Calais,” one disgruntled trucker vented on Twitter.

Pinto said the protest was over losses caused by some countries’ practice of electric pulse fishing. French fishermen say pulse fishing in demarcated zones is depleting fish numbers. The technique uses electrodes to emit electric waves, stunning fish which then float upwards and are scooped up by giant nets.

“We’re at our wits ends. We feel abandoned,” said Pinto, who together with his colleagues already frets that Britain’s exit from the European Union will end their access to British waters.

The European Parliament on Jan. 16 voted in favor 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.