Manta Rays and Chinese Traditional Medicine

From the blue, it glides towards me: a huge, dark manta ray, swimming effortlessly from the depths. It reaches the surface and floats motionless like a creature from another world. Then it banks left and swims lower in a series of loops just below me, exposing its white underbelly and 3 metre wing span. Then it dives deep, only to return for another fly-by. Its graceful moves and massive size leave me gasping.

Every diver dreams of encounters like this but they are becoming increasingly rare. There may come a day when few - if any - manta rays remain.

While working on a book about shark finning, I started to notice a trend in fish markets around the world: manta rays lined up in rows to be sold for their meat and gill rakers. Research and encounters with marine scientists revealed that manta rays are becoming increasingly valuable for their gill rakers (finger-like projections of the gills that help filter-feeding animals retain food), which are used in Chinese medicine. Manta rays caught accidentally by gillnet fishermen hunting tuna are now almost always kept. The meat is dried and salted for human consumption while ray cartilage is used as a filler for shark fin soup. Demand for gill rakers has given rise to unsustainable manta ray fisheries off the coasts of Mexico and the Philippines.

In 2004, manta rays were identified by the Convention on International Trade in Endangered Species (www.cites.org) as a group associated with significant unregulated, unsustainable fishing and severe population depletion. In 2005, the IUCN Red List of Threatened Species (produced by the International Union for Conservation of Nature and Natural Resources) classified the manta ray as "near threatened". The governments of Mexico and the Philippines made it illegal to capture and kill mantas, but then lifted the bans. Both countries list their local stock of manta rays as DD/NT - "data deficient" and "near threatened".

According to Dr Andrea Marshall, lead scientist and director of the Manta Ray and Whale Shark Research Centre, in Mozambique: "The IUCN assessment states that if current fishing practices continue, certain populations are vulnerable to extinction in the future. I don't think it is likely that they will go globally extinct but it is possible that populations will go, or have gone, regionally extinct. I also think some species of manta are more vulnerable than others and need more comprehensive management efforts."

In Sri Lanka, at the small fishing port of Mirissa, we count 23 dead manta rays in one morning. According to the fishermen, manta rays are landed every day here, in just one port in one town in one country. The next day, at the same spot, we count 20; the following day, 15. I have never seen so many manta rays in one place. The mantas are sold in two parts: the head and the rest of the fish. The head fetches 500 rupees (HK$33), including all 10 gills. Once sold, the manta's head is hacked up to get to the gills.

The same fishmongers who were finning sharks, now go to work on the manta rays' heads, separating the gill rakers from the fleshy parts that hold them in place. These concertina-looking filters are much in demand by Asian restaurants and diners. The rest of the ray is either sold cheaply to locals for use in fish curry or is left to waste.

We are told that the gill rakers and shark fins are taken to a warehouse in Matara, 30 minutes from Mirissa.

Upon arrival, we find shark fins all over the floor, divided into piles according to species; long-finned mako sharks, hammerheads, oceanic white-tips. The traders are keen to talk and invite us to take a closer look. Inside, on shelves, are clear plastic sacks crammed with dried manta ray gill rakers. The proprietor tells us that each of the four sacks contains gill rakers from about 100 manta rays. We are taken to the roof, where gill rakers and shark fins are being dried. According to the staff, 1kg of shark fin sells for 1,500 rupees while the same weight of gill rakers sells for 4,000 to 5,000 rupees.

Until recently the gestation period of manta rays was uncertain. Estimates ranged from one to three years. But in June 2007, a manta ray was born in captivity for the first time, at the Okinawa Churaumi Aquarium in Japan, after a gestation period of one year and nine days, giving scientists a better insight into one of the strangest and least-understood marine animals. Unfortunately, the baby manta ray died five days later - in part from injuries inflicted by its father for unknown reasons - but it provided data for what had been a largely blank page.

The birth allowed scientists to determine that mantas deliver in the wild every one to three years, although they have an annual ovulation cycle. However, scientists still don't know at what age they reach maturity. Some believe it is about six to eight years for females, who grow to between 3.8 metres and 4.5 metres across (depending on region and species). They usually have a single pup - but twins are not unknown - born measuring about 1.5 metres to 1.9 metres across. No one knows how long manta rays naturally live for but it is at least 30 years. For all scientists know, they could live for more than 100 years, like some whale sharks.

Scientists fear that a combination of slow maturation, long gestation and infrequent pregnancies means manta ray populations cannot replenish themselves as fast as man is catching and killing them.

According to Marshall, manta rays, which are found worldwide in tropical and temperate waters, are divided into at least two, possibly three distinct species, with visually identifiable characteristics, as well as unique behaviour and lifestyles. There is the pelagic, elusive, migratory manta and its smaller cousin, the resident ray, which lives in the same area year-round and is often encountered around coral reefs, where they congregate to be cleaned by parasite-eating fish or to feed.

They could attract millions of dollars in eco-tourism, which could play a part in their conservation. Eco-tourism generates the money and attention needed to influence governments and increase public awareness of the plight of creatures such as the manta ray. Hawaii generates US$2.5 million annually through manta ray eco-tourism. But experts warn that eco-tourism can also be destructive and unsustainable if it is not controlled or regulated and it can have just as negative an effect on a population as fishing.

Demand for dried gill rakers for traditional medicines has increased dramatically; the skin, meat and gill rakers of a mature Indonesian manta sell for up to HK$125, according to the Manta Pacific Research Foundation. In Hong Kong, gill rakers - called peng yu sai - are believed to reduce toxins in the blood by purifying and "cooling" it, especially in those whose core temperature is too warm, according to practitioners of traditional Chinese medicine. Also, as shark fin becomes harder to find, rakers are being offered as an alternative, increasing demand further.

The manta ray may not be endangered yet but unless they are given some protection, these creatures soon will be. It's time to reflect on the mistakes we have made and move to a more sustainable and frugal way of life - for the future of all living creatures, including ourselves. http://www.mantas.org/modules.php?op=modload&name=redirect&file=home

April 19, 2009. By Paul HILTON : MANTA RAY CHINA, HONG KONG PHOTOGRAPHER