Sushi is edging the pacific bluefin tuna toward extinction. The swiss-based international uion for conservation of nature's (iucn) issued a warning yesterday that placed the fish on its 'red list' of threatened species along with the chinese pufferfish, american eel, australian black grass-dart butterfly and chinese cobra. Pacific bluefin tuna is used in sushi and sashimi dishes,is at risk as the globle food market places "unsustainable pressure" on the species and others. As most of the fish caught are juveniles that have not yet reproduced , the population has dropped by 19-33 percent over the past 22years.