The average size of whale sharks visiting Ningaloo decreased from over 7 m to 5.5 m between 1994 and 2004, and also declined in abundance by up to 40% (Bradshaw et al 2008). The exact cause of these declines are unknown though up to 10% of sharks have scarring consistent with boat strike suggesting this is a major source of mortality (Speed et al 2008). Once whale sharks leave Australian waters they are exposed to fishing pressure and are worth up to $200,000 US each. Historically whale sharks have been fished in Indonesia, India, Cuba, Phillipines, Bangladesh, Maldives, Pakistan and Iraq. For example, 1000 sharks were taken from Indian waters in 1998, and in 2000, 600 were taken. Although they were officially protected in 2001, illegal fishing is still likely (Hanfee 2001). Other human activities that cause whale shark mortality include incidental entanglement and entrapment in fishing gear. Whale sharks are often caught in ghost nets that have been lost by the fishing industry (Rowat unpub data). Also many individuals are taken for display in aquariums where most die within a year.