Fisheries
Fisheries targeting mantas and mobulas first documented in Indonesia several years ago, are cropping up in India, Mozambique, Tanzania, Mexico, Ecuador, Peru and other places where they are known to congregate. Manta and mobula fishing has become big business. Easy to hunt, the rays are pulled from the ocean either with fine gill nets or spears and slaughtered en mass to meet growing demand. And now, these rays may be facing extinction – well before we are able to uncover all of the mysteries they hold.
Similar to their cousins, the sharks, the life history of manta rays makes them highly susceptible to overfishing – even more so than some of their cousins. A single fishing fleet can easily wipe out a local manta population in weeks or months, with little chance of rebound given their slow reproduction, limited local populations, and lack of migration for some of the species. Their slow maturation and reproductive cycles have raised serious concerns for the future of these species. The IUCN assessment states that if current fishing practices continue, certain populations are vulnerable to extinction.
Growing demand for the manta ray, the ocean's gentle giant, and its close cousin the devil ray or mobula, in part thanks to the loss of regional sharks, has transformed subsistence and localized ray fishing into a global, commercialized, export operation. For instance, in one fishing village in Indonesia alone, fishermen are catching over 2,000 mantas each year. In the Philippines, reports from the Bohol Sea region – a location where a major manta fishery was centered - indicate that mantas are now rare in many places where they were once common. In Sri Lanka on a single day, we counted 23 mobula rays lined up at the small fishing port of Mirissa. According to the fishermen, manta and mobula rays are landed every day here.
Demand
Though mantas and mobulas can be targeted for their meat, skin, and cartilage – and are even used as shark fin soup filler, where their cartilage is mixed with low grade shark fin for cheaper versions of the soup – they are primarily targeted for their gills to be used in traditional Chinese medicine. The rays' branchial gill plates, which filter plankton from seawater allowing the manta to eat, and constitute a small percentage of the animal's weight (just like shark fin), are highly sought after. And, it is this demand that is most devastating for these rays. Fishing fleets are hunting mantas globally from Mozambique to Brazil to Sri Lanka, just for their gill rakers.
Although we have not identified scientific evidence that support any claims, Chinese practitioners believe the consumption of gill rakers – called peng yu sai - help reduce toxins in the blood by purifying and cooling it, reducing body temperature and aiding blood circulation. A belief that these gills boost the body's immune system, especially when swine and bird flu make daily headlines, has further boosted demand. One kilogram of gill-rakers from a mature Indonesian manta sells for up to USD200 in the dried seafood markets of China. Its surge in popularity is making dried and ground gill rakers even more valuable than shark fin. The high value of the gill-rakers and the relatively scarcity of supply, has caused demand for gill-rakers to increase dramatically in recent years.
Awareness
It is understandable how the general public has largely overlooked the issues facing mantas and mobulas – which are hauntingly similar to those facing their cousins – the sharks - because very little information actually exists in public domain on the subject. One has to conduct a thorough investigation to piece together a full and accurate picture of the situation. It seems, with all the attention sharks are now getting, we have collectively forgotten about their magnificent close cousins – the rays.
All over the world, many species of rays face local fishing pressures and are the common by-catch casualties to indiscriminate fishing methods – as are many shark species. In European waters, particularly the Mediterranean, the giant devil ray is classified by the IUCN as endangered. This loss is occurring daily but few are know about it.
Indeed, the general public, and even most ocean enthusiasts, are largely unaware of the gill-raker trade and the tragic toll it taking on manta and mobula populations throughout the oceans. While addressing overfishing of these species is extremely important, if the manta/mobula fisheries are not addressed with urgency, these charismatic animals will be gone before the world takes notice.
Protection
No international laws, and only a handful of national laws exist to prevent this impending disaster, as mantas are only protected in six small areas in the world (Maldives, the State of Hawaii, the island of Yap, the coast of Ecuador, the Revillagigedo biosphere (in Mexico), and the Yaeyama Islands, Japan. Even in these 'protected' locations, there is evidence that illegal fishing still occurs. It is hard to believe we may lose this animal prior to truly understanding them, their significance to our oceans, and the important lessons they (and the secrets their evolution holds) have to teach us.
In 2004, manta rays were identified by CITES as a species associated with severe depletion and the IUCN red lists mantas as "near threatened". However, regionally, it is clear we are losing mantas and mobulas, and that the trade is following the same pattern of shark fin business – undoubtedly with many of the same players involved. Without urgent intervention, protection, and public support, these magnificent ocean creatures may silently disappear before our collective eyes.
