Engineering firm BiFab has notified staff and the Scottish Government of the potential for redundancies.
Union leaders warned on Monday that 260 jobs could go at yards in Fife and Arnish on Lewis by the summer.
In November, the yards were threatened with closure over a dispute with a major sub-subcontractor on the Beatrice wind farm contract for the Cromarty Firth.
The Scottish Government brokered a deal to stave off administration until the end of the project but BiFab said work is almost complete with no future contracts currently in place.
The company said it was working with the government, Scottish Enterprise and unions "to do everything possible to avoid redundancies within the business".
A BiFab statement said: "As we approach the end of the current project - and no further work is currently secured beyond, BiFab are going through a natural down-manning process and as such, through our statutory obligation we issue HR1 forms to notify the government of potential redundancies to permanent staff, where numbers proposed could exceed 20 employees.
"Issuing of the HR1 is part of the collective consultation process to inform staff about potential planned redundancies and not a decision that redundancies will take place.
"This type of action is typical to previous positions we find ourselves in being a project orientated-type organisation."
The company has bid for new contracts which remain under tender in the renewable and oil and gas sectors.
Scottish Labour leader Richard Leonard said BiFab was a "nationally important strategic asset" for the Scottish economy and needed to be saved.
"When there's such a large amount of public money being invested in renewable energy it's about time we made demands that the job benefits from that investment stay in Scotland," he said.
"I don't think it's unreasonable for us to be calling, on a cross-party basis, for a whole new approach to industrial strategy so that we have more planning in the economy and avoid this almost incessant lurch from one industrial crisis to the next."