Where gentle persuasion fails, shock therapy works. In an attempt to wean diners off shark fin soup, Singapore-based environmental group Sea Shepherd Conservation Society is planning to put up posters in schools and public places showing cooks in gas masks and chemical protection gear before serving bowls of the delicacy to guests.

The same image will be displayed on postcards and distributed free in Singapore, Hong Kong, Malaysia, Taiwan, San Francisco and China. The postcard will bear a warning: "Shark fins may contain high levels of mercury. Eat them at your own risk.'