The two-month dispute over MyFerryLink has resulted in damage estimated to be as much as €2 million on one of the ferries they occupied.
The director of the Calais port said the industrial action has cost the port €10 million this summer.
During the occupation, all the alcohol in the bars was downed during parties. Televisions, sound equipment and fridges were reported to have been stolen, according to the owners Eurotunnel.
In addition, hundreds of seats were destroyed.
“Somebody systematically slashed every single seat, bench and armchair in the cafés, bars and public areas,” said John Keefe, Eurotunnel spokesman. The seats cost between €300 and €500 each, and the total amount of damage done to the ships could be more than €2 million.
He added that the bars were trashed, cash registers smashed and equipment taken.
The strikers used the lifeboats to bring people on board for parties. Replacing or repairing them, and the emergency evacuation chutes, could add several hundred thousand euros to the bill, he said.
“We know exactly who these people are and what they have done and we are not going to leave it there," said Mr Keefe.
Eurotunnel had been obliged to offload MyFerryLink and is about to hand the ships over to Denmark’s DFDS ferry operator.
About 50 French union members went out on strike over the feared loss of 600 jobs. Since July they occupied two ships in Calais. A deal reached last week will keep 402 of those jobs.
Over the August bank holiday, travellers were stranded in Calais when the workers used two lifeboats to circle the port exit which stopped ferries entering or leaving.
On land, the men were fond of burning tyres which blocked the roads and one time managed to get into the Eurotunnel forcing train service to be suspended.
The actions clearly have been a great example to the migrants huddled in Calais.
