There is a real danger that cutting fishermen's days at sea could leave them unable to catch all of their allocated quota, industry leaders have warned.
Bertie Armstrong, chief executive of the Scottish Fishermen's Federation (SFF), said measures in Europe's Cod Recovery Plan were a "big issue" for the sector.
The plan, agreed in Brussels in 2008, includes further automatic cuts in days at sea for Scottish fishermen. Despite an increase in cod stocks, it also seeks to cut the amount of the fish that can be taken from the North Sea by 20% next year.
With key European talks to determine fishing quotas getting under way in Brussels next week, MSPs are to debate the issue on Wednesday.
Ahead of that the SFF warned the fishing industry is facing a significant threat from further cuts to the number of days that fishing vessels can put to sea.
Mr Armstrong said: "The big issue facing the industry is the EU's long term plan for cod, which is widely recognised by scientists, fisheries managers and the industry as simply not working. Indeed, even the EU's own scientific advisory body states that the cod plan is flawed.
"It is very easy to focus on the longer term and hope that the introduction of regional management under the new Common Fisheries Policy will be the panacea that will cure the current framework of ill-fitting fisheries management regulation. But this will only be the case if the EC totally loosens its grip on fisheries control, and there is still great uncertainty whether that will ever happen.
"Our most pressing concern is the prospect of further cuts in the number of days that fishing vessels can put to sea for next year. There is very real danger that our fleet will not have enough time available to catch its fish quota."
The debate comes after Fisheries Secretary Richard Lochhead branded the Cod Recovery Plan a "legal straightjacket which threatens to cause yet more obscene waste in our seas". He told MSPs last week that the European Commission had "stubbornly insisted on its rigid requirement" to impose further automatic cuts in days at sea for Scottish fishermen this year.