The RMT trade union has declared a formal dispute with CalMac Ferries Ltd - raising the prospect of strike action disrupting Bute transport links.
The union issued a statement on Thursday announcing that CalMac had failed to provide satisfactory reassurances over job security, conditions of service, pensions and the continuity of lifeline services to the islands of the Clyde and Hebrides.
The union will shortly begin balloting members for both strike action and action short of a strike.
RMT general secretary Mick Cash said: “The clock is ticking and the union has no alternative but to ballot CalMac members for strike action and industrial action short of strike action, in order to secure our members’ rights during this period of increasing uncertainty and insecurity.”
The RMT represents crew members on CalMac’s Rothesay-Wemyss Bay ferries, though those on the Rhubodach-Colintraive crossing are members of a different union.
A spokesman for CalMac Ferries Ltd said: “We are disappointed that the RMT has outlined its intention to ballot for industrial action given the bulk of these issues were only raised with us on Monday.
“Discussions on pensions are due to commence next week but the RMT have chosen to act before we have had an opportunity to finalise pension reform proposals and consult fully with our employees.
“We have a timetable in place for formal consultations with our staff and unions, a process which is designed to help us reach a fair agreement on an acceptable set of proposals.
“These demands for assurances include a number of other matters which have not previously been raised with the company.
“While we would welcome discussion on all these issues, we believe it is far too early in the consultation process to be talking in terms of a potential dispute.
“Should the possibility of industrial action arise we will strive to minimise the effect on our communities and employees.
“Clearly we remain hopeful that any unnecessary dispute can be avoided and we don’t lose sight of delivering a lifeline service over a busy summer period.”
The RMT’s CalMac announcement comes just days after the union’s members working for Network Rail voted in favour of both strike action and action short of a strike in a dispute over pay, raising the threat of disruption to train services which link with Rotehsay ferries at Wemyss Bay.