"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.

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."

Source:  http://news.bbc.co.uk/1/hi/world/europe/8194105.stm

Anyone know how effective this tactic will be? The boulders will provide surfaces for vegetation and corals to attach to whilst at the same time acting as a physical deterrent to those that wish to trawl the area. A three tonne boulder will no doubt ensnare or rip a net open.

Perhaps the same could be repeated in waters elsewhere if this is successful?