Despite its name, the whale shark is actually the world’s biggest fish and not a whale at all. It is a peaceful, inquisitive animal that feeds by sweeping up small ocean life in its huge gills.
In recent years there has been a growing eco tourism industry in Australia, Africa, Ecuador and the Philippines to cater for people that want to swim with them.
Although this has led to a surge in sightings, much remains unknown about them and the World Conservation Union labels them vulnerable to extinction.
However, a new report based on sightings at Ningaloo on the west coast of Australia has actually shown a slight increase in whale shark numbers. The 12-year study, published in the journal Ecological Applications, has used a pioneering photo recognition system to analyse 5,100 underwater images. The photographs were taken between 1995 and 2006 by researchers, divers and eco tourists.
Brad Norman, an Australian marine conservationist was awarded the prestigious Rolex award for his part in developing the system, which compares the unique pattern of spots on the skin of a whale shark.
Mr Norman, along with US colleagues Jason Holmberg and Dr Zaven Arzoumanian used astronomical software developed originally by Nasa to map stars.
The population models also showed that about two-thirds of the whale sharks visiting the northern part of Ningaloo reef are returning visitors.
Mr Norman wants to encourage tourists and divers across the globe to submit whale shark photos to his global identification library, called Ecocean.
The system allows anyone who has photographs of whale sharks, anywhere in the world, to upload them to the site. They have just announced the identification of the 1,000th specimen.
“It’s a major milestone, for science and for conservation,” said Mr Norman, “And it was achieved with the help of ordinary people who want to study and protect this wonderful creature.”
The 1,000th image was provided by Simon Pierce, a marine biologist studying whale sharks in Mozambique.
It is hoped, that as this database grows it will help to answer key questions about the biology and ecology of the whale shark. These include the size of the current population, the identification of critical habitats such as breeding areas and the presence or absence of migration pathways.
Due to their large size (up to 15 metres long), they have few natural predators but their fins and other body parts are often seen in Asian markets. The meat is highly valued and sells in some countries for large sums, while the cartilage is used in Chinese medicine.
Mr Norman is confident that his system can be used for other animals. “It’s going to open up a new world in animal recognition. Manta rays have dark markings on their undersides; even the pattern of whiskers on big cats can be used in identification. This will be very helpful in studying their population dynamics.”