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Gill rakers demand threatens manta and mobula rays

By Dave Armstrong - 17 Jan 2012 19:18:0 GMT
Gill rakers demand threatens manta and mobula rays

Mobula tarapacana via Shutterstock

The manta ray (M. birostis) and the mobula attract people wherever they can be seen. Unfortunately, it's unlikely they will now be seen by many. Without our knowledge, or at least the large percentage of us who didn't know, their gill rakers are being used in Guangzhou in amounts estimated at up to 80,000kg per annum. Even the sellers and patients who hope to find them healthy are unaware that they are eating manta and mobula rays. Despite being unmentioned in the official Traditional Chinese Medicine texts, the gill rakers are being exploited in a disguised way, because as much as $500 per kg is being paid.

This means that yet again, the criminal use of extremely endangered creatures, or rather their reputed and superstitious powers is being manipulated by some people in China. (Other examples include rhino horn and shark fins)

As they increase their spending power, we have seen what happens to so many of the world's conservation efforts as the Chinese literally eat away at them! Gill rakers are said to aid the immune system as, "Peng Yu Sai," (meaning fish gills) and have a presumed male kidney healing ability for ageing Chinamen. The promotion officially is as a cure for chicken pox, cancer, or any other disease or fertility problem that an ancient text may have mentioned.

dead manta rays and mobula rays

Credit and © Copyright: Paul Hilton / Manta Ray of Hope / Shark Savers / WildAid

With sharks becoming rarer, the similar cartilage from rays is used instead, while commercial interests even replace the manta itself with whale shark gill rakers. Younger practitioners of Chinese medicine tend not to use manta material, simply because it isn't included in normal studies. The fisheries stretch from Mozambique across the Indian Ocean to the western Pacific, and even Peru, but almost all mantas end up in Guangzhou. Among the nations that have banned fisheries are the Maldives, the Philippines and Ecuador along with several western countries.

The manta themselves have suffered a great fall in numbers although this is difficult to put exact figures on, largely because they have never been counted. With so many oceans involved and species as well as populations separated from each other, no one has yet produced figures good enough for CITES to quote them as endangered. Sharks get all the headlines with a similar problem, but there are multiple reasons why mantas are just ignored. The Manta ray of Hope project is now a joint effort by Shark savers and WildAid, pushing out a report with far-reaching research efforts.

The intense overfishing is producing population collapse. While "bycatch" is always a manta problem, targeted fishing is killing off whole breeding populations. This follows from the limited reproductive rate of around 16 per female (in Manta birostris), in her lifetime. One pup appears every two or three years, then takes ten or more years to reach sexual maturity. Their relatives the sharks are so different in that respect, yet they have disappeared in many regions.

SHARK SAVERS and WildAid are full of viable solutions, unlike some wildlife conservation groups. They propose that the value of ecotourism shows far more potential than any fishing (especially that which has led to reduced catches). From seven sites only, including Yap Island, $27 million has been gained directly by tour operators. $50million is the total expenditure in these sites by tourism. All of the other sites could quickly be brought into gear and double that profit, given the currently stable populations in these areas. They are mainly marine reserves, so the manta rays are not expected to be lost.

gill rakers on sale in china for medicine


In addition, CMS, a United nations Body has recently listed the giant manta. This will soon lead to a CITES regulation if figures for populations can be ascertained. IUCN classify them all as "near-endangered" at least. China especially but many other countries too, needs to address the population problems that excessive consumption has caused and is causing today. The trade in gill rakers cannot compete with this proposed extension of tourism interest, and it is likely we can't have both in the current situation. For a start, there are no locations where sustainable fishing has been tried, if indeed we need to kill these animals for such a needless purpose.

Information from the report, The Global Threat To Manta And Mobula Rays, provides further data on the problem and in particular the fascinating species involved. The two Manta species are up to 9 metres across, while even the seven Mobulas can be 5.2m. The smaller spp. are only 1.1m, and possibly are familiar in the same way as other rays such as stingrays or eagle rays.

It's likely that familiarity is a problem for most readers, just as none of us knew about this strange trade until that whistle was blown. Populations of the big M. birostris are estimated at 100-1000 individuals only, with the reef manta, M. alfredi, only a little better off at 100-2000. This fish travels less and is probably composed of varieties specialised in certain reefs. The death warrant for some of these populations is already signed. 80% declines for example have been recorded over 9 years in Mozambique (M. alfredi). Sri Lanka drastically needs to re-think its 50% of all global landings at 47,000 mobulid rays. Mexico has already reached that situation and the Manta spp. have been extinct in the Bay of Cortez for several years. Nevertheless illegal mobulid catches are regularly reported there.

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Topics: Fish