Top world chefs launched a campaign Tuesday to protect over-exploited fish species by promoting alternatives such as the humble anchovy, sardine and herring in their restaurants.

A score of gourmet celebrities said they would serve sustainable fish options from June 8 in a campaign titled "Save the Oceans and Feed the World".

The star chefs included Spanish chef Ferran Adria and Britain's Ashley Palmer Watts, head chef of London restaurant Dinner by Heston Blumenthal.

Responding to a call by the marine environmental campaign group Oceana, they launched the initiative in San Sebastian, a major culinary hub in the northern Spanish Basque region.

The campaign aims to promote the culinary use of fish such as herring, anchovies and mackerel to protect other species threatened by overfishing and stimulate production of these smaller species.

Oceana says that better exploiting such species could also provide a cheap source of protein for tens of millions of people suffering from hunger.

Such so-called "forage fish" are plentiful but are typically made into powder or oil to feed other fish species or animals in farms, Oceana says.

More than a third of all fish catches worldwide are used to make such secondary products, according to the UN Food and Agriculture Organisation.

Oceana's chief executive Andy Sharpless said he hoped the big name chefs -- many of whom have Michelin stars -- would influence other cooks and the public to change their habits.

Spanish chef Pedro Subijana, who has three Michelin stars, said some types of fish were ignored in the kitchen because cooks did not know what to do with them.

"Our job is to teach them," he said.