The Scottish Government has been accused of breaking promises by allowing harmful forms of fishing to continue in protected areas.
Environmental campaigners have discovered severe damage to the seabed around the Isle of Rum, even though it was designated the Small Isles Marine Protected Area (MPA) in 2014 in a bid to conserve its rich biodiversity.
However, no fisheries management measures have ever been put in place, meaning the area is being decimated by dredging and bottom trawling, which continues to be legal.
Phil Taylor, from campaign group Open Seas, said: “It’s not protected, it’s a line on a map that means very little.
“The government has made an active decision to allow this and, as a result, we’re finding harm like this is happening.”
In a joint operation, Open Seas and Greenpeace UK carried out surveillance work in the area, collating evidence of the damage being caused.
They want damaging forms of fishing to be completely banned from sensitive coastal waters.
The Scottish Government said it was committed to delivering fisheries management measures for the existing MPA network, including the Small Isles MPA, by March 2024.
But Mr Taylor said the approach would be too little too late.
He said: “There have been plans to establish management in this site since 2014.
“It’s totally inadequate to say there are plans and that those plans will solve what we’ve lost. These are habitats that will not return in our lifetimes.”
A Scottish Government spokesperson said: “We have also committed to designate 10% of Scotland seas as Highly Protected Marine Areas by 2026.
“This will prevent all extractive, destructive or depositional activities, including all fisheries, aquaculture and other infrastructure developments, while only allowing other activities, such as tourism or recreational water activities, at non-damaging levels.”