Fishing leaders and politicians will bid to stop what has been called the "worst ever threat" to the white fish industry during talks in Brussels.
The proposals could threaten the white fish fleet
The European Commission wants to cut the number of days Scottish vessels can spend at sea by a quarter.
Trawlers may only be allowed to work for two-and-a-half days each week.
Fisheries Minister Ross Finnie said huge efforts already made by the fishermen should count in their favour in the crucial talks on Tuesday.
The Scottish Fishermen's Federation (SFF) said the plan made no sense because many stocks are in robust health.
The talks will decide the permitted days at sea for most vessels fishing for white fish.
The European Commission has rejected calls from scientists for a ban on fishing for North Sea cod but will consider a 25% cut.
The SFF has claimed this would have serious direct implications and also for those who catch cod as an unintended by-catch when looking for other species, such as haddock and prawns.
The sea fishing industry remains a highly important part of the Scottish rural economy. There are around 7,300 fishermen in Scotland with a further 8,600 working in fish processing.
In 2000, the total value of landings was around £300m. The industry is concentrated in the north east and the west Highlands.
The federation is looking for a roll-over of this year's restrictions, which reduced cod catches by 15%.
Chief executive Bertie Armstrong told BBC Scotland: "This proposal is the worst threat ever faced for days at sea and would take the fleet into unviability.
"That's a great frustration because these fleets are actually harvesting from perfectly sustainable stocks.
"We have made some monumental sacrifices over the last five years, a 65% reduction in the number of white-fishing boats."
Mr Finnie said the fishermen were under "real pressure" from scientists who favour a complete ban on catching cod.
"We have trimmed back so much, you get to a point where if you go too far you simply plunge the fleet into a non-viable position," he said.
"And that could have completely the reverse effect of trying to conserve stocks - you push fishermen and others into a completely impossible position."
The minister said he would be aiming for a roll-over but warned of the scale of the task.
"Despite the fact that there are better signs of recovery for cod in the North Sea, the fact remains that cod is below its safe biological limits," he said.
"That is quite a serious position and is the context in which these difficult negotiations will take place.
"We have made huge efforts in the Scottish fleet and that really is the substance of our argument. It's not as if we have ignored the science at all.
"We have taken very serious measures over the last three or four years."
RSPB Scotland applauded the fleet's "huge efforts" to reduce its fishing power.
However, it argued that the only cod which should be allowed to be caught should be the fish accidentally taken in other fisheries.
Marine policy officer, Kara Brydson, said: "We urge the ministers to have a vision of our waters as a fragile eco-system, and to show the political will to protect it."