The proper reaction to this is to remove the fishermen by force and then put some in jail for criminal behavior. If the Police and the Coast Guard won't do it, the Army and the Navy will.
The French State needs to start exerting some control over the destructively crazed portion of its population... god dammit.
The very reason we have government is so that people's issues are resolved in ways other than by violence of one part of society over another - especially, as in this case, over people who have nothing to do with it.
Governments exist to stop this very thing.
A government that doesn't is inept.
The French are exceedingly inept. And proud of it.