Diving with Manta Rays

They are magnificent creatures and anyone lucky enough to have dived with manta rays can confirm this: they are very inquisitive too! They don’t have a stinging barb, so no chance of you getting ‘speared’ either. If you haven’t spotted them yet, you better try quick though, because manta ray populations have declined by as much as 80% in several regions over the last 75 years and by more than 30% worldwide.

Did you know manta rays are part of the shark family? Here are some other quick facts about these graceful marine creatures:

• How big do they get?

Manta rays (Manta birostris) are the largest rays and can grow to more than 7m (wingspan) and weigh 1000-1300 kilos. After whales and the whale sharks they are the next biggest marine species on the Great Barrier Reef.

• What do they eat?

Just like whales, Manta rays are filter feeders who feed on plankton and krill. This is consumed through their gills with the help of their gill ‘rakers’:, which are comb-like projections.

• Where can they be spotted?

Manta rays can often be seen along coasts and offshore islands. Giant manta rays are found in tropical, sub-tropical, and temperate waters of the Atlantic, Indian, and Pacific Oceans. In Australia there are quite a few places where you can encounter them in the water while scuba diving, with top spots being Ningaloo Reef, from Coral Bay or Exmouth and some places on the Great Barrier Reef. Mantas can even be spotted from a boat or shoreline because they occasionally leap clear of the water to land with a slap. It is believed they do this to get a female’s attention.

• When to go?

Between June and November is the best time to go encounter them in tropical Australian waters. How fast do they reproduce? Female manta rays are pregnant for a year and have one pup at a time. Babies are wrapped in a thin-shell that hatches inside the mother. On average they only give birth every two years. This is exactly the reason why the species is threatened by overfishing, because it takes a long time for Manta rays to reproduce.

Red List

The most recent estimation is that the worldwide value of manta-based tourism and filming is US$100 million per year. But this is not what is threatening them. Manta rays are under increasing threat from Asian demand for their gill rakers, which are used in Chinese medicine. So: fishermen actually target manta rays, as incredible as it sounds. And to do so is easy: they are huge, approach the surface often, they move slowly, and are very predictable. Some sub-populations now count just a few hundred individuals. At some locations manta rays are already depleted.

Manta rays are not currently protected by any fisheries legislation in Australia.The International Union for Conservation of Nature Shark Specialist Group, based in Canada, has added the Giant and Reef manta rays to its Red List of Threatened Species last month, an upgrade from the list of nearly-threatened species.

HAVE YOU EVER SEEN MANTA RAYS UNDERWATER? Tell us about your encounter below and/or post your photos on our Facebook wall!