Divers say a combination of spear fishing and the indiscriminate use of blasting has destroyed marine life off a remote South China Sea Island Exotic marine life at a prime diving site in the South China Sea is being wiped out by a lethal combination of mainland blast fishing and recreational fishing. Pedro Blanco - an isolated rock pinnacle 85km east of Hong Kong - was home to a colourful variety of exotic sea life including blue marlins, mantas, reef rays, octopuses and turtles until mainland fishing boats and Hong Kong spear fishers began targeting it. Fish stocks have now fallen to the point where it is in danger of becoming worthless as a diving location, according to marine experts Charlie Frew and Andy Cornish. The pair have appealed to the Guangdong government to stop mainland fishing vessels using bombs around Pedro Blanco and are writing to the Hong Kong Underwater Association to express concern about the number of spear-fishing expeditions. Mr Frew, who runs diving company Asiatic Marine and has dived at the site for seven years, said blast fishing had increased to levels where it was hardly worth diving at the 200-metre wide rock any more. 'Diving there used to be out of this world - now it's dismal,' he said. 'There is no selective fishing. They are going after everything. It's like the Wild West - it's a free-for-all. 'Just last week, two boats had been blast fishing just before we arrived. Large fish could be seen lying on the sea floor and hundreds of little reef and bait fish were floating on the surface, drifting with the current.' Blast fishing was a danger to divers if the crews did not know anyone was there. 'It's pretty frightening if you are not expecting it,' he said. Dr Cornish, an expert at the Swire Institute of Marine Science at the University of Hong Kong, said: 'If you were to rate them on a scale of zero to 10 from low to huge impact, spear fishing would be a seven or an eight and blast fishing would be a 10.' A large surge in the number of Hong Kong people diving with a corresponding increase weekend expeditions by spear-fishing teams had accelerated the decline of fish stocks at Pedro Blanco, Dr Cornish said. 'I have dived in a lot of places in Southeast Asia and the Caribbean, and Pedro Blanco was some of the best diving I have ever done,' he said. 'It's bathed in a current that passes the Philippines and had all sorts of tropical fish never recorded in Hong Kong waters.' Explaining why it was important to preserve marine life at the rock, he said: 'There are at least 10,000 divers in Hong Kong and most of them spend their time diving overseas. Here is a fantastic place on their doorstep and it is being trashed.' He described the activities of spear fishermen as 'underwater carnage' and said he had seen dive boats taking up to 40 people a day to the site. 'There has got to be a realisation by the operators that it is totally unsustainable,' Dr Cornish said. 'They are destroying things not just for everybody else but for themselves as well.' After Dr Cornish wrote to the Guangdong Marine Fisheries and Agricultural Bureau alerting them to the problem of blast fishing, patrols appear to have been stepped up but the area is too remote for regular patrols. Dr Cornish and Mr Frew are now seeking help from the Hong Kong Underwater Association to try to persuade spear-fishing tour operators to limit expeditions. Association chairman Simon Yu Kwok-kuen was not available for comment.