An emergency meeting is being held on Inis Mór tonight after a fresh threat to transport to the island emerged.
Residents said they have been told Aran Island Ferries will cease operations to Cill Rónáin harbour in mid January.
It would leave the island without a scheduled daily service. Ferries currently run to and from the mainland twice a day, all year round.
The island co-operative said the company made the decision after it lost a Supreme Court Appeal against passenger levies imposed by Galway County Council in 2012.
The council imposed an 80c charge on tourists landing on the island, along with an annual charge of €5 for residents.
The local authority voted to introduce the charge in January 2012, following an extensive redevelopment of the harbour, costing almost €50 million.
Aran Island Ferries now plans to cease sailings from Ros a Mhíl to Inis Mór on 17 January.
This evening, Cathy Ní Ghoill of Comharchumann Forbartha Árann said residents were dismayed by the latest developments and would discuss the matter in detail at tonight's meeting.
The threatened withdrawal of ferry services comes just months after islanders were engaged in another protracted campaign over the future of air services to and from the mainland.
