Under recently announced plans, the reduced sailings would continue until at least February 6.
As a result of positive Covid tests and staff isolating, CalMac is unable to operate to full capacity, with 203 members of staff unavailable due to Covid.
With numerous staff testing positive or self isolating, a temporary timetable was introduced on January 3 running until at least January 23rd. This is now been extended with the number of ferry services reduced by around 15 per cent.
In addition to reduced services, Stornoway, Ullapool, Uig, Lochmaddy, Lochboisdale, Castlebay, Armadale, Mallaig, Coll, Tiree, Ardrossan and Brodick will be operating reduced hours.
Robbie Drummond, CalMac managing director, said: “We fully appreciate the difficulties these changes will cause for some of our customers, and we apologise for any disruption to their journeys over the next few weeks. I am very grateful for their continued patience and understanding at a time of intense pressure.
“We will continue to review the temporary timetable on an ongoing basis and will add services back in as soon as we possibly can. However, a return to a full service will require a significant reduction in the level of staff absence.
"In the meantime, we will continue to operate as flexibly as possible to ensure we restore sailings where and when we can. Over the past week we have restored a full timetable to the Gourock-Kilcreggan and Colintraive-Rhubodach routes.
“Community feedback is also important at this time. In response to recent feedback, we altered the temporary timetable on the Portavadie-Tarbert route in Argyll to ensure that local schoolchildren could get home from school, a change we were happy to make for the local community.
“All services, irrespective of timetable or service change, are subject to change, cancellation, or interruption at very short notice. We would ask all customers to check service status before commencing their journey to ports, but sailings may be cancelled right up to the point of departure.”
Affected routes are:
Largs - Cumbrae
Oban - Coll - Tiree
Oban - Colonsay
Mallaig - Lochboisdale
Wemyss Bay - Rothesay
Tarbert (Loch Fyne) - Portavadie
Gourock - Dunoon
Oban - Craignure