Fishermen have been protesting in their boats in response to an "unacceptable situation" about landing their catches.
The entrance to St Helier Harbour was blocked on Wednesday morning as Jersey fishermen sounded their horns and set off flares. They say they have not been allowed to land their catches in France since Brexit, but the French still have access to island waters.
Jersey's environment minister says the new rules have impacted both sides.
Jersey Fishermen's Association says fishermen are being prevented from landing shellfish in France and is calling on the States to do more. The president of the association, Don Thompson says he wants a discussion with ministers about this "unacceptable situation".
"I have to say fishermen would rather be fishing than holding a peaceful demonstration in the harbour, but fishermen's backs are up against the wall and we're losing boats from our fleet."
Mr Thompson said fishermen were getting "desperate" and they needed a solution to protect their fleet. "I suspect this may just be the start of a show of force," he added.
Jersey's environment minister John Young said he was not "making light" of the issue and did understand the "feelings and passions" of the fishermen. The changes caused by Brexit have caused "major issues for Jersey and for our French neighbours", he said.
Prior to the protest, Deputy Young told the BBC: "We're not the only community affected by this, the EU is calling the shots... we're all trying to find ways through this so we can get to a stable place." The minister for external relations, minister for environment and the assistant minister for environment have signed a statement saying they will do "everything possible" to protect and sustain the industry.
It says there will be a meeting between ministers and some fishermen next week.
Also, if French vessels were banned from Jersey's waters it would "apply equally to Jersey vessels" it read.