More than 85 percent of the world's fish supplies have already been fully exploited according to scientists - and by 2050 the stocks will be entirely exhausted. Jonathan Baillie, director of the Zoological Society of London (ZSL) said today: "More than one billion people use fish as their primary source of protein. "15 percent of the world's fish are already endangered and most of the top predators like tuna and salmon have experienced declines of 90 percent of higher. "Currently we are fishing to a rate where the fish cannot replenish themselves and we are drastically depleting the biological diversity in the ocean. "If we continue, in the future there will be fish in the ocean but they will be smaller and not the fish we are used to.

We are fishing to a rate where the fish cannot replenish themselves and we are drastically depleting the biological diversity in the ocean Jonathan Baillie, director of the Zoological Society of London

There will be more jellyfish and crustaceans instead of larger fish. What we will be able to get out of the ocean will change a lot." The figures come as scientists launched Project Ocean - a campaign to prevent overfishing and other methods such as bottom trawling which destroys thousands of kilometres of seabed each year. Professor Baillie added: "Currently only 1 percent of the world's oceans are protected, we would like to increase this figure to 30 percent. "Some 85 percent of the world's fish stock is already fully or over-exploited and by 2050 the world's fish stocks will have collapsed entirely, if we don't take action."

He went on: "There will be 9.2bn or even 10bn people on the planet in 2050, those people will need to be fed and if we destroy the fisheries that will only put more pressure on the landscape which means remove the remaining forests to grow crops and increasingly biofuel usage." Greenpeace also today backed the campaign. Biodiversity spokesman Willie MacKenzie said: "If we don't change our ways a world with no fish is where it is going. "Atlantic Salmon is commercially extinct, cod off the Grand Banks and eels are now hugely endangered. What used to be relatively common species of fish have got down to very low levels.

"We hunt fish rather than harvesting them - the ones we like to eat are high up on the food chain which has a drastic impact on the eco-systems. "There are solutions and ways to do it better and this is something which we can effect. One of the biggest things we can do to change the situation, is as a consumer by being selective." Tuna and salmon are two of the most endangered fish species in the world's oceans. Years of badly managed and over-fishing has left tuna in trouble and even previously healthy fisheries are now under pressure. Of the 23 commercially exploited tuna stocks globally, at least nine are classified as fully fished, four are classified as overexploited or depleted. Three stocks are classified as critically endangered and a further three a vulnerable to complete extinction.

The UK is the second highest consumer of tinned tuna in the world. In 2006 alone, the country consumed the equivalent of more than seven hundred million tins of tuna, a total of over 130,000 tonnes and worldwide, the tinned tuna trade is worth around US$ 2.7 billion per annum. Small fish species are also often targeted, Prof Baille added: "As humans we have become such effective hunters, we used to think that fish was inexhaustable but we are just hoovering up all the major fish sources in the ocean. "As larger fish become extinct, there is more and more pressure upon smaller fish to fill the void."