The manta ray — a valuable ocean resource — is in drastic decline across Southeast Asia.

This week, in Thailand at the Conference of the Parties on the Convention on International Trade in Endangered Species (CITES), Indonesia has a chance to vote on doing something to stop that decline. Brazil, Columbia and Ecuador have proposed to add manta ray to the list of species protected in international trade under CITES. We think Indonesia should vote “yes”. Legally and economically, the proposal makes sense.

The giant manta ray is a majestic, highly migratory, ray native to Indonesia. Once common, since 2011, the International Union for Conservation of Nature (IUCN) has included mantas in their Red List of threatened species as vulnerable to extinction. Fishermen are hunting mantas mainly to supply China’s huge demand for their gill plates. These gill plates are used in purported traditional medicines in China, Hong Kong and Macau.

Indonesia is the world’s largest exporter of dried manta gills for Chinese medicinal trade. Some estimates indicate Indonesia slaughters over 1,320 a year for this trade, ranking just ahead of Sri Lanka (1,055), and almost double that of India (690), which sits in third place according to a 2012 report by manta ray of Hope, a consortium of scientific experts and NGOs working to protect the manta. Manta gill plates now sell for upward of Rp 240,000(US$24.7) per kilogram in Guangzhou, China, where 99 percent of the market ends up. These high prices lead many fishermen and traders to seek to supply the market, and many traders to work as “market-makers” to further stimulate demand.

Legally, the manta proposal submitted to CITES makes sense, because it tracks the recent moves in Indonesia itself and growing tenor of Asian consensus. In February this year, Indonesian authorities announced a shark and manta ray sanctuary in a 46,000 square kilometer zone in Raja Ampat, West Papua, within the rich marine ecosystem of the Coral Triangle. Within the sanctuary, shark and manta fishing is banned.

Among other countries, the Philippines has laws protecting mantas, and prohibiting their slaughter and export. The Maldives also has a law banning the export of manta products. And Sri Lanka has a law that requires export permits for all fish, which should include mantas.

Further, in November 2011, Sri Lanka, India, Pakistan, the Philippines and 16 other countries, agreed to list the manta ray as covered by the Convention on Migratory Species (CMS), which supports international cooperation for the protection of migratory species amongst the nations through which they migrate. These Asian countries agreed to try to immediately protect the manta, and to work with other states to conclude more detailed agreements for its conservation and management. Thus, further manta protection laws should result.

Economically, although Indonesia is a large exporter of manta ray gill plates, and the CITES proposal would restrict or eliminate their export, the manta ray proposal also makes economic sense for two reasons. First, Indonesia stands to gain from potentially astronomic tourism revenues.

Currently, Indonesian fisherman selling gill plates get cash amounting to only about 20 percent of the retail sale value. More than 80 percent of the profits go to the international traders and to the Chinese retailers.

Local fishermen get different cash prices depending upon the size of the manta, with the average manta fetching the fisherman Rp 1 million — Rp 2 million. But in China, the gill plates of the same manta might get five times that amount. Thus, the Indonesian manta ray population is being locally decimated to enrich the pockets of foreign traders and retailers.

And the current high prices, are leading to exploitation of this hidden resource at a rate that is entirely unsustainable and will lead to their complete demise within years, like other similar species.

The Sri Lankan shark fishery, for example, declined by about 87 percent from 2000 to 2008, from about 34,380 to 4,410 sharks, when they tried to meet China’s demand for shark fins. How long until Indonesia’s manta rays suffer the same decline?

Indonesia also stands to benefit from a CITES listing and later protecting mantas at home because of tourism. If the estimated number of 1,320 dead Indonesian mantas a year is correct, then the total annual value of these mantas sold to China, is roughly Rp 2 billion — which may seem enormous. However, as nearby scuba diving resorts in the Maldives and Yap suggest — the potential value of manta tourism is far greater.

In Yap, Micronesia, an entire tourism industry of Rp 40 billion annually is based upon tourists coming to Yap to swim and dive with manta rays. In Kona, Hawaii, the value of 100 tourists paying to dive or snorkel with manta rays each night, amounts to Rp 500,000 each night and Rp 18 billion a year. Although a range of other variables affect precise numbers, one thing is clear — mantas draw scuba divers and snorkelers who pay big to see them.

Because manta rays are a migratory ocean species, it is not enough for Indonesia to protect them. Indonesia needs to ensure other countries protect mantas too. Otherwise, migrating mantas will be slaughtered when they pass through other countries.

This would defeat Indonesia’s recent move to protect mantas in Raja Ampat. Indonesia needs mantas to have a CITES listing to encourage other states to do the same, and ensure other states establish a permit trading system for manta parts. At CITES, Indonesia would be smart to care about a fish, and right, to vote yes, for the giant manta ray.

Stamps Howard, president, Wildlife Technology and Kala Mulqueeny, principal counsel (who is an environmental lawyer currently leading work for the Asian Development Bank on Combating Wildlife Crime and CITES), have written on the importance for Indonesia to protect manta rays, and the global initiatives taken to protect manta ray.

The views expressed are those of the authors.