Activists drop rocks on the seabed - filmed by Greenpeace
Greenpeace has begun sinking boulders in EU-protected cod fishing grounds to prevent what it says are destructive forms of fishing in the area.
The environmental group says it will drop 180 boulders off the Swedish and Danish coasts to prevent fishing boats from dragging nets along the sea bed.
Greenpeace says the bottom-trawling fishing method destroys both the sea bed and the marine environment.
Sweden's government described the group's action as "unnecessary".
Agriculture Minister Eskil Erlandsson said marine protection was already on the EU agenda.
Writing on Saturday in the Swedish newspaper Dagens Nyheter, Mr Erlandsson said the Greenpeace actions posed a threat to a Danish-Swedish agreement not to fish in parts of the Kattegat (waters between the two countries shared by the two countries) where cod spawn.
Greenpeace spokesman Staffan Danielsson told AFP news agency that the granite boulders, weighing as much as three tonnes, would be sunk over the next week.
They would have "no negative impact on the environment", he said.
The Greenpeace project highlights the ongoing debate over the environmental damage caused by over-fishing, in which the size of catches is not the only concern for campaigners.
The environmental impact of different methods of fishing is also a major issue, correspondents say.
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