The extension to the protection areas came into effect on Friday
Seabirds are being given greater protection in Scottish waters, the Scottish government has announced.
Protection areas on land have been extended out to sea to help birds such as the guillemot, puffin and gannet.
The 31 extension areas will reach between one and four kilometres out to sea, depending on the species.
They include St Kilda, an archipelago with World Heritage status, the Forth islands, parts of Shetland, Orkney and Highland and Aberdeenshire coastlines.
Environment Secretary Richard Lochhead said: "It is vitally important they receive suitable protection throughout their lives at sea and on land."
"A seabird's marine habitat is as crucial to its ability to survive as nesting sites on dry land."
Andrew Thin, chairman of Scottish Natural Heritage, said: "This is an important measure for the long-term conservation of seabird populations around our coasts.
"In recent years significant declines have been recorded in the breeding success and size of key Scottish colonies for many species."
Stuart Housden, director of RSPB Scotland, said: "Seabirds on RSPB Scotland reserves have recently suffered a run of terrible breeding seasons and, although this year was better, it's vital that we do all we can to protect them and the food resources they need to prosper."
The area extensions came into effect on Friday following consultation last year.