Four Greenpeace activists have been released on bail after being arrested in the Netherlands for blocking a controversial super trawler destined for Tasmania.

The activists' actions postponed the departure of the 142- metre FV Margiris for almost a week.

The blockade ended overnight with police arresting the protesters.

Greenpeace spokesman James Lorenz says the ship is now en route to Devonport, where it will be based while fishing Commonwealth waters.

"It will be in Australian waters around about the 20th of August," he said.

The ship is being brought over by Seafish Tasmania, but has attracted widespread criticism with conservationists and local fishermen concerned about overfishing.

In a statement, the company says its 18,000 tonne quota for jack mackerel and red bait is only 5 per cent of the total fishery, leaving 95 per cent of stocks to maintain the wider ecosystem.

While the company is yet to be granted a licence by federal agencies, it says basing the Margiris in Devonport will boost the local economy by about $15 million.

Seafish Tasmania maintains the Margiris will be regulated through an onboard observer from the Australian Fisheries Management Authority.