The protest, which is demanding an end to destructive fishing methods, coincided with high-level negotiations taking place in Glasgow at the United Nations climate summit COP26.
Slogans in English and French were projected on the facade of Bute House, in the capital’s Charlotte Square.
Messages included “save the fish, Sturgeon”, “don’t touch my bottom” and “Boris is tangled in industrial fishing”, as well as “La mer est vide”, which translates as “the sea is empty”.
As well as the projections, three ‘mer-folk’, complete with tails and crowns made of sea litter, and a large sculptural fishing trawler trailing deep sea nets were used as visual symbols of the protest.
The demonstrators, who shed clothes for the demonstration, made a plea to Scotland’s Nicola Sturgeon to take the lead and help keep the ocean alive.
They are calling on the Scottish Government to “reverse years of neglect and harm” caused by trawling and dredging and “start to take the environment seriously, protecting it for the livelihoods and survival of the young”.
The protesters say the destructive harvesting methods are destroying the coastal waters of Scotland and state support for them must be ended.
They say the impacts of industrial fishing are “an environmental tragedy which decimates fragile coastal fishing communities” and Scottish fleets should switch to low-impact techniques such as creeling and diving, which they say will protect coastal waters and increase job opportunities in local communities.
A number of campaigners took part in the demonstration, including ‘off-grid millionaire’ and environmentalist Roc Sandford, a member of Ocean Rebellion.
He said: “Humanity has declared war on fish and we’re winning.
“The ocean is so depleted that small fishing communities are on the edge of survival and areas of former plenty are now empty.
“Over 100 million people rely on inshore subsistence and small-scale artisanal fishing for their daily food and livelihood, often using the same waters targeted by bottom trawlers.
“It’s a no-brainer to ban bottom trawling, both on climate breakdown and nature breakdown grounds.
“Climate breakdown and nature breakdown are effectively the same thing and both have to be stopped now.”
Another Ocean Rebellion protester, Rob Higg, said: “Imagine how much damage a net bigger than a jumbo jet causes as it drags across the seabed.
“It catches everything in its path – whatever that might be – destroys marine life and releases the ‘blue’ carbon stored there.
“Bottom-trawling emits more greenhouse gases than aviation. That’s a lot of gases.”
There should also be no expansion of fish farming in Scotland, according to the protesters.
They are appealing to ministers to take heed of findings from a Scottish Parliament inquiry and impose a moratorium on new salmon farms and limit expansion until the sector becomes more environmentally friendly.
Mr Sandford said: “Salmon farming is destroying Scotland’s coastline, loch by loch, and with it the jobs of countless local people who depend for their livelihood on clean and living seas.
“Our leaders are betraying us.
“No more excuses, Nicola – implement the settled will of the Scottish Parliament with a moratorium on salmon farms.”