Each year large numbers of Chilean devil rays, the largest of the mobulid rays, visit remote sea mounts in the archipelago of the Azores. The discovery of these aggregations has transformed the region from an important fishing ground into a Mecca for divers wanting to encounter these graceful rays, which have become a major target in the gill-plate trade. Ana Filipa Sobral is studying the mobulid rays of Santa Maria and has partnered with international organisations to ensure their protection.
It is 6.45 am and the sun has just appeared from behind the majestic Pico volcano as our boat leaves Horta marina and heads towards Princesa Alice, a sea mount located 45 nautical miles south-west of Faial Island in the Portuguese archipelago of the Azores. The sky is a mix of orange and purple and the sea is flat, its water the colour of platinum. A three-hour journey lies ahead.
Although I have done some diving before, this will be my first dive so far offshore. It’s a long trip but there is plenty to see on the way, from resident sperm whales to turtles and sunfishes. I have just started my thesis on Chilean devil rays Mobula tarapacana but haven’t come face to face with one yet, so a local dive operator has kindly offered to take me out to the sea mount. I’ve heard so much about Princesa Alice, my enthusiasm and expectations are at an all-time high as we get closer.
We finally arrive and there is no land in sight – we are in the middle of nowhere in the Atlantic Ocean. I feel incredibly small as I realise just how vast is the expanse of water around me. While the crew drops anchor, I give a short talk about the devil rays and ask the divers to try to get belly photos of them for photo identification. After the safety briefing everyone rushes to gear up before jumping into the ocean.
At last I am in the water and it is of the deepest blue I have ever seen, with a clarity that is unbelievable – from the surface it is possible to see the top of the sea mount 35 metres (115 feet) below us. I go down to it but ascend again rapidly, wanting to have as much time as possible to look for rays. Hanging onto the anchor line in a blue world, I wait for whatever may pass by. And I don’t have to wait long. Within a few minutes, four golden shadows glide gently up from below. They swim by, performing a perfectly synchronised ballet: three males chasing a female and mimicking her movements. I watch in astonishment.
At the time it didn’t occur to me that, exactly 116 years before, Prince Albert I of Monaco and his crew were probably experiencing the same sense of wonder. The leader of a research expedition aboard the Princesa Alice, Prince Albert was just starting a deep-water survey here. Expecting the sea floor to lie a few thousand metres below them, he and his crew discovered rocky ledges just 241 metres (790 feet) down. They explored the area and realised they were floating above an extensive platform that supported an amazing diversity and abundance of life, especially of commercially interesting fishes. The following day Prince Albert sent a telegram to Carlos I, the king of Portugal, announcing the incredible discovery and telling him about its importance to the Azorean fishery. The sea mount was named after his research vessel and the prince continued to study it on subsequent visits.
The Azores is one of the few places on earth where Chilean devil rays gather in large groups. We know that these rays are among the ocean’s deepest divers, but otherwise they remain a mystery to us. What will researchers discover with the use of remote underwater video stations?