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Devil rays in distress: Protecting the “mini mantas”

By Shawn Heinrichs, Safina Center Fellow

Caption: Devil rays (M. tarapacana) circle above seamounts in the waters off Azores, Portugal
Devil rays (M. tarapacana) circle above seamounts in the waters off Azores, Portugal

In recent years, manta rays have gained significant international attention as iconic marine species, in large part due to a concerted effort to raise awareness for these magnificent animals and the threats they are facing from unsustainable fisheries. However, manta ray’s smaller cousins the mobula rays, a genus of nine described species commonly referred to as ‘devil rays’, have remained largely obscured from the public eye, but are just as threatened as manta rays.

Caption: Dead devil rays line the streets of an Indonesian fishing port
Dead devil rays line the streets of an Indonesian fishing port

Back in 2009, while investigating shark fisheries in Southeast Asia, we uncovered an alarming trend – fishermen who hunted sharks for the shark fin trade, were now also targeting manta and devil rays. The question we had to answer was, why? A series of investigations revealed that the primary driver for these manta and devil ray fisheries was the expanding market for their gill plates, the feather-like structures that these rays use to filter plankton from the water.

Indonesia Manta Fishery

Dried seafood traders display bags of gill plates from hundreds manta and devil rays
Dried seafood traders display bags of gill plates from hundreds manta and devil rays

Dried gills plates are transported through traditional shark fin trade routes to China, Singapore and Hong Kong. It turns out that shark fin traders, in a move to offset diminishing profits due to growing scarcity of large shark fins because of overexploitation, had revived an relatively obscure, psuedo-medicinal coastal remedy in China call Peng Yu Sai. Peng Yu Sai is a soup consisting of boiled manta gills, seahorses and pipefish that is ‘prescribed’ to treat fevers, chickenpox, and even as an aid to breastfeeding mothers. The traders then began marketing this ‘remedy’ as Traditional Chinese Medicine (TCM) despite the fact that interviews with TCM practitioners revealed that Peng Yu Sai was in fact not considered a part of TCM.

Manta rays (M. alfredi) feed at night under bright lights in the waters off Kona, Hawaii
Manta rays (M. alfredi) feed at night under bright lights in the waters off Kona, Hawaii
Devil rays (M. munkiana) dance under bright lights at night in the waters off La Paz, Mexico
Devil rays (M. munkiana) dance under bright lights at night in the waters off La Paz, Mexico

In response to the imminent threat facing manta rays, a collective of government and non-government organizations, researchers, and passionate individuals rallied and successfully lobbied to secure appendix 2 protection for manta rays at the 2013 Convention on International Trade in Endangered Species (CITES), a UN treaty of 183 member nations. This was a huge win for manta rays, making headlines across the globe and precipitating a slew of follow on protective legislation, including the establishment of manta sanctuaries in Indonesia and Peru.

Curious little devil rays (M. munkiana) come in for a closer look in the waters off La Paz, Mexico
Curious little devil rays (M. munkiana) come in for a closer look in the waters off La Paz, Mexico

Unfortunately, the conservation wins experienced by manta rays have largely not been shared with their smaller cousins the devil rays. The sanctuaries that now afford protection to manta rays do not include devil rays. And worse yet, market surveys conducted by WildAid between 2010 and 2013 in China, the global hub of the gill plate trade, revealed that the number of devil and manta rays represented in the dried gill plate market had tripled, with most of the increase coming from small-to-medium gills from devil rays! We are now killing more than 150,000 devil rays every year for the gill plate trade, compounding the effects of massive losses from bycatch in other fisheries.

Devil rays (M.tarapacana) spend time investigating divers in the waters off Azores, Portugal
Devil rays (M.tarapacana) spend time investigating divers in the waters off Azores, Portugal
Devil rays (M. tarapacana) spend time investigating divers in the waters off Azores, Portugal
Devil rays (M. tarapacana) spend time investigating divers in the waters off Azores, Portugal

Like mantas, devil rays take a long time to reach maturity and produce only one pup per pregnancy. This low productivity means that even moderate fishing can quickly wipe out regional populations. Unregulated fisheries have already devastated devil ray populations, and some local populations have almost disappeared, while other major declines have likely occurred unnoticed. If trends continue, these gentle animals will be driven to the brink of extinction. Protecting devil rays will also make it easier to enforce manta ray protections, as the specialized training to distinguish between the gill plates of different species will no longer be required. Effective conservation of mantas and devil rays requires that we protect both.

Fishermen land their catch including a large devil ray (M. tarapacana) in southern fishing port in Sri Lanka
Fishermen land their catch including a large devil ray (M. tarapacana) in southern fishing port in Sri Lanka

Every three years, delegates from CITES member nations meet to decide if certain species of fauna and flora receive international trade protection. This September, CITES will be hosted in Johannesburg, South Africa, and a proposal to list devil rays on Appendix 2 will be put to vote. The outcome of this important vote will likely have massive implications for the future survival of these rays.

Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico
Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico
Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico
Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico

Devil rays have relatively large and complex brains and they are known to be curious and social animals. In so many ways they look and behave like ‘mini mantas’! Devil rays are also known aggregate in large numbers, making for an incredible dive experience but also exposing them to serious threats from targeted fisheries. If people appreciated how curious, gentle and vulnerable devil rays are, we would have a public outcry demanding immediate protection of these special animals. Our mission is deliver this message home, inspiring nations to support international protection of devil rays at the CITES conference and then return to their counties and implement national protections. The international gill trade and other fisheries are having a devastating impact on devil ray populations, and time is running out to save these animals from extinction.

A small devil ray (M. hypostoma) passes in the blue in the waters off Isla Mujeres, Mexico
A small devil ray (M. hypostoma) passes in the blue in the waters off Isla Mujeres, Mexico

WE must act now, with one voice, to protect them.

Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico
Devil rays (M. munkiana) aggregate to feed on tiny shrimp under lights in the waters off La Paz, Mexico