The discovery emerged in tests taken on the first day of a two-month scientific research voyage to assess the impact of plastic pollution on Scotland’s internationally important marine wildlife.
More than 150,000 gannets make their homes on the Bass Rock, alongside puffins, guillemots, razorbills, shags, fulmars and kittiwakes.
The area also supports the biggest puffin colony on the east coast of the UK.
But shocking pictures taken on the landmark island reveal plastic rubbish strewn across the ground, around nests and even in the beaks of seabirds.
The researchers have been dismayed at the extent of man-made pollution affecting the Forth and its resident wildlife.
“Being surrounded by tens of thousands of gannets on the Bass Rock is a stunning spectacle, but it’s seabirds like these which are acutely threatened by ocean plastic pollution,” said Willie Mackenzie, oceans expert at Greenpeace UK. “We found plastic bags, packaging, bits of old fishing gear and even crisp packets strewn across the island and surrounding eggs in nests.”
Experts from the Scottish Seabird Centre in North Berwick have been assisting with the studies.
Tom Brock, chief executive of the centre, highlighted the importance of the research and welcomed the opportunity to work with Greenpeace.
“Scotland’s amazing marine wildlife is of international importance. However, it is now facing a wide range of significant threats, including plastic pollution,” he said.
“Research and the raising of public awareness are vital to ensuring that our wonderful wildlife can be appreciated and enjoyed by future generations.”
The survey team will continue sampling as they sail up the east coast to Inverness, then cut through the Caledonian canal and Loch Ness to reach the west coast. Tests will be carried out over the course of the voyage, which takes in basking shark hotspots around Oban, Iona and Mull.
Divers will also be analysing the waters around the islands of Eigg, Rum and Skye, which are important for wildlife including dolphins, whales, diving birds and seahorses.
The team will move on to the Outer Hebrides, visiting the remote Shiant Isles – a mecca for puffins and razorbills.