Boats are to be used in an attempt to herd a pod of northern bottlenose whales back out to sea.
Rescuers will attempt to shepherd the animals out of Loch Long amid concern over the impact a major international military exercise planned for the area could have on them.
The British Divers Marine Life Rescue Medics (BDMLR) have monitored the pod for the last month in and around the River Clyde.
A pair of whales first seen in Loch Goil were then spotted at the mouth of the Clyde near Millport on the Isle of Cumbrae.
Since then five whales have been spotted in separate locations in Loch Long, with some entering smaller lochs nearby.
The team, with the Ministry of Defence (MoD) and locals, has been carrying out routine monitoring of the whales to prevent any disturbances to them.
The MoD alerted the BDMLR to the planned Exercise Joint Warrior in the area and, as whales are particularly sensitive to underwater sounds, the rescuers hope to herd the animals out to sea using a number of boats on Thursday.
A spokesman for BDMLR said: “This will be a very carefully planned operation carried out under our licence from NatureScot for exactly this type of situation where we need to try to move free swimming cetaceans to safety.
“This of course does come with risks of its own and there is no guarantee it will be successful given the depth of water and distance that needs to be covered, so will be undertaken with as much care as possible.
“We will of course reassess our actions and options if the whales decide that they will not go.
“We are very grateful for all of the support the team has had from the local residents and boat operators who have offered their assistance with this, as well as the MoD, who will be joining the BDMLR rescue boat coming in from Fife to carry out this operation.
“All we can do now is wish everyone involved the very best and hope for a positive outcome.”
Northern bottlenose whales are a deep-diving species of cetacean normally found off the edge of the continental shelf to the west of the UK and Ireland.