Whale Shark

7:30pm Sunday, 31 Jan 2010  Nature  CC G 

Whale sharks may well be the biggest fish in the sea but very little is known about them. Whale Shark follows the whale sharks on a year-long journey to try to find out more.



The
whale shark is the largest fish in the world and yet it remains a
scientific mystery. For the majority of the year they make their way
slowly though the oceans relatively unnoticed. However, on the eve of a
spectacular coral spawning event on Australia’s Ningaloo Reef, hundreds
arrive. Six weeks later, they disappear. Where do they go?



New
findings suggest that whale sharks from Australia, Africa and India
could all come from the same migratory population - meaning that this
would be the largest migration on earth. But how can we find out for
sure?



Australian marine biologist Mark Meekan, tags eight
sharks in Ningaloo. Thanks to specially designed on-shark cameras, DNA
testing and satellite tracking devices, we can follow their dramatic
journey. Mark’s theory is that the sharks are driven on their massive
journey around the world by major food events, such as occurs in the
Ningaloo Reef.



To test his theory further, Mark moves to the
tropical island of the Seychelles, where marine biologist David Rowatt
has spent the last 10 years building up the world’s largest database on
the whale shark population. Using the latest photo-identification
software, they start to compare the distinctive spot and stripe
patterns of over 3000 whale sharks - a single match would prove Mark’s
theory, and be invaluable in helping to understand more about their way
of life.



The information could also be used to save them.
Commercial fishing of whale sharks has only recently been banned in
South East Asia, but not before a substantial diminution of their
numbers. According to research whale sharks are now on average 2m
shorter than they were a century ago, highlighting the damage caused by
human action.