Schooling shortfin devil rays at Pulau Si Amil in Sabah, Malaysia, have seen the location formally recognised as an area of interest for shark and ray researchers, following a new study published in the journal Pacific Conservation Biology.
The shortfin devil ray (Mobula kuhlii) is one of the smaller species of devil ray, with a maximum wingspan of around 135m. They are close relatives of manta rays, but are less commonly encountered by divers due to their more elusive and pelagic nature. The species is currently listed as Endangered on the International Union for the Conservation of Nature (IUCN) Red List.
Although they are occasionally spotted as solo animals, they are known to aggregate in groups known as ‘fevers’, which can sometimes number in the hundreds. The aggregations around Pulau Si Amil were first spotted by recreational divers with popular local operator Scuba Junkie, with visitors treated to regular sightings and schools of up to one hundred rays at a time.
Sightings recorded by divers were passed on to marine biologists at Universiti Malaysia, Sabah (UMS), together with photos and videos of the rays, to help researchers put together a picture of the rays’ distribution.
‘The presence of devil rays at Si Amil provided a unique opportunity for divers to contribute to citizen science efforts, as well as giving them a most memorable experience.’ said Dr Mabel Manjaji Matsumoto, Associate Professor at Borneo Marine Research Institute, UMS. ‘The video footage and numbers collected were invaluable for our records, and were used to produce the scientific paper, and set the baseline for further studies in this area.’
It is not currently known why the devil rays are schooling around Si Amil. ‘Schooling behaviour is normally associated with safety, reproduction, socialising, cleaning or feeding,’ said Dr Gonzalo Araujo from Marine Research and Conservation Foundation. ‘It could be a combination of these drivers too. It would be fantastic to carry out research in the area to find out more.’
Although the schooling devil rays are an exciting development for local divers and scientists alike, the researchers warned that urgent steps must be taken to protect the devilrays as soon as possible. ‘The species is not protected by law, and neither is the area in which they were seen,’ said Dr Mabel. ‘This, coupled with their schooling behaviour, leaves them very exposed to overfishing – especially from large-scale commercial fishing practices.
‘Devil rays, like many other sharks and rays, do not produce many offspring – normally one pup per litter – and catching them in large numbers would be catastrophic for a species already under threat,’ continued Dr Mabel. ‘The expansion of Marine Protected Areas (MPAs) or creation of a Locally Managed Marine Area (LMMA) could be explored to both facilitate the protection of these species and make the most of this incredible spectacle through tourism, much like how Pulau Sipadan Marine Park is a world-renowned tourist attraction.’
The new study notes the findings of a previous report which suggests sharks and rays contribute an estimated US$10million in tourism revenue to Sabah. Protecting them is essential not only for the preservation of the species but also the local economy.
‘It is prudent that protection is given to either this area or to the species, and preferably to both.’ said David McCann, lead author of the study. ‘Manta rays, for example, are already protected by law in Malaysia. Protection is necessary following the globally recognised ‘precautionary principle’ – and would ensure these rays are in Sabah in perpetuity – enabling further investigation to determine how and why this devil ray species uses this area, as well as enable the authorities to explore potential future revenue streams from responsible dive tourism.’
‘The area is already world-renowned for spectacular diving and what can be found here,’ continued McCann. ‘These sightings show that there may yet be more to be found and reported. Hopefully appropriate measures will be taken to protect these incredible animals and their habitat.’
