More than a fifth of CalMac ferry staff are absent due to Covid-19 with lifeline services facing “immense pressure”.
The surge in cases is more than twice as many of the frontline staff who were absent due to the infection on Hogmanay.
The ferry service said there was currently no way for it to operate full capacity due to more than 20% of crew now self-isolating.
The latest figures show that 151 crew and 35 port staff are currently unavailable because of Covid-19.
CalMac’s managing director Robbie Drummond said it was focusing on keeping essential deliveries going to affected communities.
“The absence of so much of our frontline staff is placing immense pressure on our ability to maintain a normal service,” he said.
There is a legal requirement for a minimum number of crew on board for ferries to operate under maritime law.
Positive cases on a vessel mean replacement crew must be sourced, resulting in sailings being cancelled if they cannot be found in time – meaning cancellations can take place at very short notice.
Despite introducing an essential services timetable on January 3 to help the ferry service cope with coronavirus absences disruption is likely to continue for some time.
Mr Drummond said: “There is a possibility that your sailing may be disrupted or cancelled, so please check the status before you start your journey to a port. As this situation is constantly developing, cancellations may also take place at very short notice.
“Help to protect passengers and crew by wearing a face covering in port offices and inside ferries, and please do not travel if you have tested positive and are still within the self-isolation period, even if you feel better.”