Manta Movement , call for manta

A few weeks ago, we sent you a call for manta sightings along east Australia as the mantas were not around at North Stradbroke Island for about 2 months in December and January. This is normally the peak aggregation period at this location. Your helpful replies informed us that the mantas seemed to have been in mass numbers around Lady Elliot Island and Heron Island, which is quite unusual for the season. Also few mantas were sighted further south (NSW), when they usually are only sighted in February.

We are really interested in any manta sighting information you can provide even without photos. It gives us good indication about the seasonality of the mantas in different regions.

Lady Elliot Island Field trip

Once again, we had an amazing field trip at LEI in early February 2010 with our EarthWatch volunteers. We encountered 25 mantas and identified 18 of them including 6 new individuals.

During this trip we also tested our acoustic receivers placed all around the island using a special acoustic tag (called range test tag). We tested whether the receivers can detect the signal from the acoustic tag continuously over a 24hour period and to what rang the receiver can detect the signal (around 500m).

We also downloaded the data from the listening stations, which revealed that some of the tagged mantas have been hanging around the island since June with short periods of absence while others totally disappeared after a certain period of time.

This is important as it shows that some mantas may be resident to Lady Elliot Island and use the habitat all year around while there may undertake longer migrations. A big thank you to AATAMS for access to equipment and expertise over the last year.

We also collected data on the temperature, current direction and current strength around the island relative to tidal cycles. This allowed us to confirm that manta rays tend to start feeding during the outgoing tide at LEI, when the current brings important concentrations of plankton to the island. Several mantas were sighted feeding during the trip and we had the opportunity to swim with them and observe their feeding behaviour.

In addition, plankton tows were conducted all around the island to monitor the plankton community in relation to the different tidal scenarios. Plankton tows were also conducted in the feeding trails of mantas, which shall help us to determine food preferences of these giants.

It was a very busy trip, but it didn’t stop us from having a lot of fun. The baby turtles hatching was an amazing sight to behold!

Our next trip to LEI will be from the 20th of June to the 3rd of July. It will be the peak season for manta rays aggregation. On the program:

• Lots of photos to ID as many mantas as possible (diving and snorkelling)
• Lots of current, temperature and other parameter measurement around the island
• Lots of plankton collection
• Taking tissue sample from manta rays (biopsy) for genetic and diet determination
• Documentary filming
• Acoustic receiver deployment around the island at specific sites
• Satellite tag deployment on mantas

If you would like to become a volunteer for Project Manta at Lady Elliot Island and be part of a great adventure, please contact EarthWatch Australia :

http://www.earthwatch.org/australia/exped/townsend.html
Contact Andy Donnelly at scienceprogram@earthwatch.org.au

Manta database

Our database keeps growing bigger and bigger, we now have 373 mantas identified in only 15 months, this is an amazing great effort and it is mainly thanks to all the photos you have sent us!

We recently received lots of photos from different part of the east coast, we really appreciate the effort you put in to help us, and one more time THANK YOU for your help, it is highly valued!

It is important to note that of the 373 animals, 333 were photographed at Lady Elliot Island, and that 20 of these individuals were also sighted at NSI. It would be great to be able to gather photos from animals observed in other regions along the east coast and to show that soe of these animals may be able to travel great distances from the northern Great Barrier Reef to southern NSW.

If you have any manta photos or information you would like to share with us please do at l.couturier@uq.edu.au or call at (+61) 073409058 / 0431545900. You can also join our facebook page: PROJECT MANTA-The manta rays of eastern Australia. This page is regularly updated and allow our contributors to easily communicate with us and each other. You can also upload your own photos to share if you wish to.

The Project Manta Team

Lydie Couturier
Fabrice Jaine
Dr Kathy Townsend
Prof Mike Bennett
Dr Scarla Weeks
Dr Anthony Richardson