The Manta Gill Raker Trade


Photographer Jason Isley and cameraman Roger Munns recently visited Sri Lanka to film and photograph blue whales. During the trip they took time out to visit fish markets at Mirissa and Negombo, primarily to document the growing trade in manta gill rakers.

Their large size, slow speed and tendency to be near the surface make manta rays easy targets for fishermen but the perceived poor quality of their meat has traditionally meant that until recently they were only threatened by subsistence fishing in remote areas or as bycatch from purse seiners or other netted fisheries. In the last few years however, demand for their dried brachial filaments (gill rakers) as ingredients in chinese traditional medicine has increased fishing pressure worldwide, turning a subsistence fishery into a commercial export industry. According to the IUCN, targeted fisheries are now present in Philippines, Mexico, Mozambique, Madagascar, India, Sri Lanka, Brazil, Tanzania and Indonesia.

During our trip to Mirissa and Negombo fish market in Sri Lanka we observed as several rays, including smaller species of mobula and full grown Manta birostris, were unloaded from fishing boats which often spend up to a month out at sea. The heads of the rays were quickly separated from the body and sold to a local buyer. Prices for wet gill rakers at market were between $5-$12 per kilo depending on the size and quality. Normally manta ray gill rakers will fetch a higher price than smaller mobula species.

Later that day our guide, Daniel, brought us to the house of the dealer we’d seen at Mirissa market earlier. In his backyard were a collection of shark fins and gill rakers drying in the strong Sri Lankan sunlight. The whole occasion was surprisingly friendly and Jason and I were both invited into the home of the dealer for tea and refreshments. After drying, the brachial elements are mainly exported to Hong Kong. At this point in the buying chain the price for dried gill rakers is between $80-$140 per kilo, again depending on size and quality. Back at home in Kota Kinabalu we found dried gill rakers for sale in dried fish shops for 350RM per kilo – roughly $120.

Some quick internet research seems to show that the end product is a powder sold as a means of detoxifying the blood stream with packets claiming to ‘clear away heat and remove toxic material in children after diseases and chickenpox’.  Currently there is no scientific data which supports this assertion but of course that does not stop people believing it. While we didn’t have the chance to visit China to observe this, we did see dried gill rakers for sale in a Chinese medicine shop in Kota Kinabalu. On asking we were told that these were to be boiled up in a soup and eaten to treat rashes.

In some good news, recently the Maldives has moved to protect the many manta rays in its waters. A recent study by Chas Anderson, Shiham Adam, Anne-Marie Kitchen-Wheeler and Guy Stevens (2010) estimates that the manta rays in the Maldives bring in over $8.1 million in tourism income to the country every year, giving the population there a rough value of $4,000 per animal per year. An income which is sustainable if the population is left alone. The one time price of catching and killing a ray is tiny in comparison and this gives the Maldives government a strong economic reason to protect what is, essentially, a valuable resource. Of course not every country with manta fisheries has the opportunity or environment to support dive tourism so in these cases alternative livelihoods have to be found for fishermen who’s income is impacted by their loss of trade.

It’s early days in our understanding of the threat that manta rays face right now, with very few facts or figures available. It’s fairly obvious though, from the anecdotal evidence that we’ve seen, that manta rays and their smaller relatives face as uncertain a future as any of the fish in our oceans.