Twenty species of abalone shellfish are threatened with extinction, including three found off Japan, according to an international nature conservation group.In its first global threat assessment of the world's 54 abalone species, the International Union for Conservation of Nature blamed unsustainable extraction, illegal poaching, climate change, disease and pollution for putting the shellfish, among the world's most expensive seafood, in danger of extinction.The three mollusk species found off Japan -- commonly called madaka abalone, disk abalone and giant abalone -- are designated as "enda…READ FULL ARTICLE
