Whale sharks populations are healthier than earlier estimated, suggests new study

December 26th, 2007 - 2:36 pm ICT by admin  

Washington, Dec 26 (ANI): A new study has suggested that whale shark populations in Ningaloo, Western Australia, are healthy, thus contradicting previous findings about the decline of the marine creature.

Brad Norman, a marine scientist from Murdoch University, along with US colleagues Jason Holmberg and Dr Zaven Arzoumanian, carried out the 12-year study.

The research team used astronomical software, originally developed for use with the Hubble space telescope, for the study.
A pattern-recognition software developed by Holmberg and Arzoumanian allowed the group to positively identify individual whale sharks. Like a human fingerprint, the speckles and stripes pattern on the skins of whale sharks are believed to be unique to each individual.
Photographs were taken while swimming alongside each whale shark, and photographing or video-taping the white lines and spots along the flanks of the animal.
Based on 5100 underwater images contributed by hundreds of researchers, divers, and ecotourists, the authors obtained almost ten times more data than any previous study.
To study whale sharks in a meaningful way, we really had to rethink how we collect data and how we analyze it, said Holmberg. The results surpassed our expectations, allowing hundreds of individuals to contribute and providing the necessary data to obtain a closer look at the populations health, he added.
The authors of the study found that more whale sharks are returning to the northern area of Ningaloo Marine Park from season to season, suggesting the population is growing. In addition they found that about two-thirds of the sharks were repeat visitors, while one-third were sighted only once during the study period.
The study also suggests that the management guidelines for whale shark ecotourism at Ningaloo appear to be on target.
The researchers hope others will apply their techniques to other whale shark populations, as well as to other species.

Listed as a rare species, relatively little is known about whale sharks, which live in tropical and warm seas, including the western Atlantic and southern Pacific.

As a rare and highly migratory fish, whale sharks are a big draw for Ningaloos ecotourism industry, where tourists pay to get close views and even swim with the sharks. (ANI)

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