The captain of a ship that sank off the coast of Africa 'started applauding and cheering' when his vessel was entirely submerged, according to anti-poaching activists who saved the man and his crew. Crew aboard Sea Shepherd vessel Bob Barker, which had been pursuing the ruined vessel named Thunder for 110 days in an effort to stop alleged poaching activities in Antarctic waters, found themselves taking on the role of saviours when the boat's distress signals were sounded. 'What was incredibly strange was that the captain of the Thunder, when the vessel did actually sink, started applauding and cheering, which I took to be very unusual behaviour and further evidence that he deliberately sank his own vessel,' Captain Peter Hammarstedt told Fairfax media. Scroll down for video . Thunder, one of six vessels known to illegally fish vulnerable toothfish in the Southern Ocean, sunk off the coast of Africa on Monday . Crew on Sea Shepherd vessel Bob Barker, which rescued those on board Thunder, said the captain of the now submerged ship was seen cheering . Sea Shepherd claims that Thunder is one of six vessels known to illegally fish vulnerable toothfish in the Southern Ocean. The conservation organisation's ships collected and delivered to authorities over 72 kilometres of illegal gillnet that it alleges was abandoned by the vessel in December. Thunder's sinking is believed to be another deliberate move by the vessel to hide evidence of any illegal activities. 'When my Chief Engineer boarded the Thunder in the hours leading up to the sinking, he was able to confirm that there were clear signs that the vessel was intentionally scuttled,' Captain Hammarstedt said. 'What was incredibly strange was that the captain of the Thunder, when the vessel did actually sink, started applauding and cheering,' Sea Shepherd Captain Peter Hammarstedt said . He added: 'I took to be very unusual behaviour and further evidence that he deliberately sank his own vessel' 'Usually when a vessel is sinking, the captain will close all hatches so as to maintain buoyancy. However, on the Thunder, the reverse was done - doors and hatches were tied open and the fishhold was opened. It is an incredibly suspicious situation, to say the least.' The alleged poaching vessel  issued a distressing signal, claiming that the ship was sinking at about 4.00pm on Monday. 'The Captain of Thunder radioed us and said their ship was sinking. We  launched our small boat and did everything we could to assist,' Mr Hammarstedt said. 'It appeared as though the ship and crew were in a serious situation.' All 40 crew members, who abandoned the sinking ship, were safely rescued and are being taken to the Sao Tome, in the Gulf of Guinea after receiving food, water and medical attention . The rescue was made despite numerous reports of violent behaviour from the vessel towards Bob Barker, including that crew had thrown grappling hooks at the ship and tried to ram it on more than one occasion . The rescue was made despite numerous reports of violent behaviour from the vessel towards Bob Barker, including that crew had thrown grappling hooks at the ship and tried to ram it on more than one occasion. Mr Hammarstedt told ABC News they have been following the 'internationally-wanted poaching vessel for the past 110 days' as part of its Operation Icefish. 'Our suspicion is that the captain of the Thunder, knowing he's run out of fuel, has deliberately sunk his own boat in order to destroy any physical evidence,' he said. 'Our suspicion is that the captain of the Thunder, knowing he's run out of fuel, has deliberately sunk his own boat in order to destroy any physical evidence,' he said. All 40 crew members, who abandoned the sinking ship, were safely rescued  off the coast of Africa and are being taken to the Sao Tome, in the Gulf of Guinea after receiving food, water and medical attention. The conservation organisation's ships collected and delivered to authorities over 72 kilometres of illegal gillnet that it alleges was abandoned by Thunder (pictured) in December . Environmentalist group Sea Shepherd ship 'Bob Barker' has rescued 40 crew members from the sinking ship . Operation Icefish has been very successful in exposing the operations of the alleged poachers and making connections between them and fishing companies in Spain. The Thunder  lost its nets, its catch and its profits for the entire season during the pursuit as they face prosecution in whichever port it is forced to go to once short of fuel and supplies. This four month chase was the longest pursuit of a poacher in maritime history, surpassing the 21-day pursuit of a Uruguayan poacher in 2003 by Australian Customs. The four month chase was the longest pursuit of a poacher in maritime history, surpassing the 21-day pursuit of a Uruguayan poacher in 2003 by Australian Customs .
Conservationist group saved fishing ship's crew as boat sank on Monday .
Group's Bob Barker was chasing the ship collecting 'evidence of poaching'
40 crew were rescused as fishing ship Thunder sank off the coast of Africa .
Bob Barker captain said Thunder skipper cheered as his boat went down .
Peter Hammarstedt said scuttling would destroy evidence of poaching .