The Sea Shepherd director has been convicted in absentia in Norway, spent 80 days in a Dutch prison, and has had the Japanese, Icelandic and Danish navies trying to arrest him for trying to defend whales, seals and fish. But now the animal rights and environmental activist Paul Watson faces the ignominy of having the flagship of his fleet, the Steve Irwin, sold by Scotland unless he raises nearly £1m in the next two weeks.

Watson, a co-founder of Greenpeace and the director of the Sea Shepherd conservation society based in California, was about to leave Lerwick in the Shetland isles en route for the Faroes last week when Maltese company Fish and Fish lodged a complaint against him in the Scottish courts over alleged damage sustained when Sea Shepherd freed hundreds of bluefin tuna from the company's nets in a a clash off the coast of Libya last year. The Steve Irwin was impounded by the court on 15 July and now the man described by the Japanese as a pirate has just days left to post a bond for £860,000.

In a statement last week, Watson said that if the group fails to post the bond, "the Steve Irwin will be held indefinitely and possibly sold. This would not only be a financial hardship but more importantly, it could prevent us from reaching the Faroe Islands to protect pilot whales and threaten our ability to defend whales in the Southern Ocean Whale Sanctuary from the Japanese whaling fleet this December."

"Fish and Fish are claiming damages for the bluefin tuna we rescued from their nets in June 2010, fish that we believe were illegally caught after the season has closed, without an inspector onboard, or any paperwork documenting the legality of their catch".

The group has reportedly raised £185,000 so far.

Watson, who has been to the Faroes twice before, plans to deploy acoustic devices to lay down "a wall of sound" in the path of migrating whales to prevent them from approaching the islands. Earlier this year, two of his ships harried the Japanese whaling fleet in the Southern Ocean near Antarctica, forcing them to suspend their hunt and return with far fewer whales than they intended to catch.

Watson told the Guardian that he intended to go to the Faroes and expected to be arrested. "Sometimes you just have to say 'what the hell' and go for it. We shall see what develops."

He added that Sea Shepherd crew members were forced to flee Namibia recently after the president declared the group "a threat to the national security".

"Apparently taking pictures of the slaughter of seals is a threat to national security! Our crew escaped through the dark, using night vision to navigate across the desert until we gained the safety of South Africa."