The coastguard's emergency tugs which patrol the waters around the Northern and Western isles are being withdrawn as part of public spending cuts.
They are two of four emergency vessels which will stop working around the UK coast, saving more than £32m.
They were brought in to help protect the coastline after the Braer oilspill off Shetland in 1993.
Shetland Islands Council's Harbour Board chairman, Alistair Cooper, said he was worried about the move.
He added that while the government seemed concerned to reassure everyone that oil and gas exploration was safe, it was prepared to remove one of the main planks if its safety regimes.
Western Isles council transport spokesman Donald Manford said he was shocked by the decision.
The tugs, which are at 30 minutes readiness to sail, will be withdrawn from September next year.
The four vessels work on a rotational basis, serving a few months in each of the operational areas around the UK. These rotations are usually based on engineering schedules.