What is the largest illegal global trade after drugs and weapons? Animals, says Maryrose Fison, and it is putting some species on the brink: "For all the international treaties, police units, campaign groups and NGOs battling it, the trade continues to grow. The world's tiger population has plummeted from 100,000 at the start of the 20th century to below 4,000 today; 20,000 elephants are killed each year for their ivory; the number of rhino poached in South Africa doubled last year; sea turtles are being harvested at an astonishing rate, their shells turned into jewellery; and, over the past 40 years, 12 species of large animal have vanished completely in Vietnam."