In the mid-water reefs of Sitio Tacdo—gan, Barangay Bagahanglad is a wide "playground" of giant manta rays which are locally called pasa-pasa.
Known in the science world as Manta birsotris, these gentle giants of the deep have been commonly sighted by scuba divers and coastal dwellers.
An adult manta ray has a wingspan of more than six meters, making it one of the five largest fish species in the world. It is a cartilaginous (soft-boned) fish known to thrive in tropical and subtropical waters.
Like other shark and ray species, the manta ray belongs to Class Chontrichthyes and Family Myliobatidae (sub-family Mobulinac). Hammerhead and thresher sharks are natural predators of manta rays, primarily because the three have a common habitat, they being reef-associated species.
A study on the biophysical environment and behavior of giant manta rays in the Bontod-Tacdogan Reef provided important information on their behavioral patterns that can help in their protection in relation to coastal resource management, particularly for the development of ecotourism in Masbate.
Tristan Paylado, a researcher of the Bureau of Fisheries and Aquatic Resources’ regional office No. 5, studied the presence of manta rays in their natural environment and their behavioral patterns with emphasis on feeding, courtship, and mating.
The Los Baños-based Philippine Council for Aquatic and Marine Research and Development (PCAMRD), a national planning agency of the Department of Science and Technology (DOST), monitored the study.
Primarily filter feeders, manta rays feed on planktons (tiny organisms) and other small or moderately sized fish.
Planktons, as food, may be the main reason for the presence of manta rays in the Bontod-Tacdogan Reef since plankton density in the area ranges from 145 to 963 cells per liter.
Courtship and mating were characterized by several stages: chasing, grasping or holding, pre-copulation, copulation, post-copulation, and separation.
Paylado said manta rays do not pose a threat to divers, except for possible collision with their pectoral (breast) fins that can knock out a diver in seconds.
These underwater creatures have their dislikes, such as being disturbed when they are courting or mating, when they are feeding, or when someone rides on them even though they seem to present themselves for mounting.
Notwithstanding their dislikes, they enjoy the company of humans in their underwater world, according to Paylado.
For instance, they are not bothered by flash photography or video. They welcome "friendly connection" such as direct eye contact.
Some manta rays enjoy the bubbles exhaled by divers on their undersides although the BFAR researcher advises otherwise.
With the increasing number of local and foreign scuba divers and tourists flocking to the Masbate reefs, the presence of manta rays in the area has provided additional income for the residents of Bulan (Sorsogon) and San Jacinto and Monreal (Masbate).
Ecotourism, however, also poses threats and disturbances to the feeding and mating activities of the manta rays.
To counteract the detrimental effects of the growing ecotourism industry on the manta rays, the BFAR cited the need to put up a tourist zone marine reserve and a preventive buoy system in Bontod-Tacdogan to regulate fishing activities, prevent the entry of drift gill nets, and minimize damage to the reef system.
The number of tourists and divers must also be limited to minimize disturbance. Closing of the reef during the mating season is also necessary to allow successful copulation among manta rays.