Manta Gill Rakers
Manta Ray © Steve Jones.

The flesh of manta and mobula rays (close relatives of the mantas and commonly known as devil rays) has always been considered poor quality by humans. As a result these animals have not been widely targeted in commercial fisheries in the past. However, in recent years this has changed, with manta and mobula rays rapidly becoming a more desirable product in the Chinese medicinal trade. The ray's feathery gill rakers have become a sought-after product worth an estimated US$11 million annually, which is driving unsustainable fisheries for these charismatic creatures.

The gill rakers are thin cartilage filaments that enable the rays to filter zooplankton from the water column. Once dried, gill rakers are the most valuable parts of the mobulid rays and drive commercial fisheries for these species, with particularly large fisheries present in Sri Lanka and Indonesia. Although the rakers comprise just a tiny percentage of the body-mass, they sell for significantly more than the rest of the body parts put together. 

Those selling or promoting the use of this product claim the rakers can treat health issues ranging from asthma, to skin rashes, to chicken pox and even cancer. Some of the practitioners also maintain that rakers reduce toxins, boost the immune system and aid in the detoxification of the bloodstream. However, reviews of available literature, along with interviews of well-respected practitioners have revealed that there is no evidence to support any of these claims, with some practitioners even admitting that gill rakers are not effective and that many other alternatives are available. 

Gill rakers are often consumed in a soup (locally called Peng Yu Sai), with ingredients also including ginseng and dried pipefish. However in contrast to the prestige accorded to shark fins (and Shark Fin Soup), gill rakers are regarded mainly as an ingredient in a medicinal product.

It appears that this growing demand is due to savvy product marketing by Chinese retailers who have exploited a relatively abundant commodity to create a new product in the medicinal industry, falsely 'reviving' a remedy which in reality does not exist in the traditional literature. One of the key marketing strategies plays on consumer fear of the increasing prevalence of modern disease outbreaks such as Bird Flu, Swine Flu and SARS. The sales pitch suggests that as these fish are able to filter particles from the water with their gill rakers, if consumed, these rakers will aid in the detoxification and purification of the consumer’s body by filtering out disease and toxins. 

Most consumers are unaware that the product comes from manta and mobula rays; indeed most consumers are not even aware of what a manta or mobula ray is and therefore have no idea of the impact their choice is having on these increasingly vulnerable species.

This information has been provided by Guy Stevens from the Manta Trust. The full article can be read in Shark Focus 44.

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