THE CONSERVATION COLUMN: Project Manta

Dr Kathy Townsend, Earthwatch scientist and chief investigator for Project Manta, Moreton Bay Research Station, University of Queensland, talks about her work with manta rays, from ascertaining behavioural patterns to protecting their future...

Manta ray - the name brings to mind an image of a large, graceful creature that seems to fly, rather than swim, through the water. Their beauty is featured in almost every marine documentary and divers spend thousands of dollars for the privilege of being in the water with them. With this in mind, you may be surprised by how little is know of these iconic creatures.

With a wing-span reaching between five and seven metres across, these gentle giants are closely related to sting rays, but without the stinging barb or crushing teeth. They are the largest bodied plankton-feeding species that forages in the warm waters of Australia’s Great Barrier Reef.

It was only two years ago that scientists discovered that there are two species of manta rays. Prior to that, it was thought that there was a single species only. This is equivalent to discovering a new species of elephant, and excited the marine biology community.

The oceanic manta (or Manta birostris) was the name originally given to the entire group. Ironically, it turned out that the newly described species, the reef manta (Manta alfredi), is the most common species and the one we most often see in Australian waters.

Unfortunately, very little is known about the biology of either species. Basic questions remain unanswered. Questions like: how long do they live? How often do they reproduce? At what age do they reach sexual maturity? How many of them are there? How many young do they produce? And how fast do they grow?

We know that mantas can be found around North Stradbroke Island, off Brisbane during the summer months, but then they disappear in the winter months. This leads us to questions of conservational importance such as: Why do they undergo seasonal migrations? How far do they go? Do they cross international boundaries?
 

While large, mantas are also graceful

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