Marine conservationists are hailing it as a significant step towards preserving a species that has been fished almost to extinction in some parts of the world. On February 21st Indonesia designated all of its massive aquatic territory as a sanctuary for manta rays. The fisheries ministry says both reef and oceanic rays will be fully protected within the archipelago’s territorial waters, which cover some 6m square kilometres (2.3m square miles). That makes it the largest sanctuary in the world.
Manta rays are much sought after in China for their gill-rakers, which are used in traditional medicine. In 2011 the International Union for Conservation of Nature added manta rays to its “red list” of endangered species. It says that the global population has fallen by about 30% during the past 75 years. In some places their numbers have plunged by 80%. In March 2013 manta rays were added to Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that the trade in them must be regulated. But Indonesia’s decision to prohibit all trade goes much further.
Indonesia, one of six countries of the “coral triangle”, the most biodiverse oceans on earth, seems to have been convinced by the economic case for conservation. According to a study published in 2013 by scientists from America and Britain, manta rays bring in about $140m a year in economic benefits globally. Indonesia alone is estimated to earn $15m annually from the divers, snorkelers and “multiplier” benefits that ray-watching tours bring to its economy. Agus Dermawan, the head of conservation at the fisheries ministry, says Indonesia could become the world’s leading destination for manta-ray tourism. (It presently comes third, behind Japan and the Maldives.) By a popular calculation (see below) a single manta ray can generate $1m in economic benefits during its 40-year lifetime. A dead one, by contrast, sells for just $500 at local markets.
Some parts of the archipelago—such as the Raja Ampat islands in western Papua, and Komodo island, home to the “dragon”—already protect manta rays, along with sharks, mobulas, dugongs and turtles. They reap the benefits from dive tourism. But in less touristy spots it may be much harder to stop local fishermen from catching manta rays. In most cases responsibility for policing the ban is likely to fall to district governments, and these often lack the capacity to enforce such laws.
Tiene Gunawan of Conservation International, an NGO that worked with Indonesia’s fisheries ministry to establish the sanctuary, expects to “start small” by working with the authorities, fishermen and park rangers where there are large populations of manta rays. Programmes developed in these waters could then be replicated in other parts of the archipelago, she says.
In the end manta rays, like other endangered sea species, will survive only if demand for them can be curbed in consuming countries. Manta rays are particularly vulnerable because they take up to ten years to mature and then reproduce only once every two years. A mother usually gives birth to just one pup at a time. And even if Indonesia does succeed in protecting its own waters, manta rays are migratory: satellites have tracked oceanic rays, whose wingspan can reach at least seven metres (23 feet), travelling straight-line distances of 1,100 kilometres (684 miles). This means that they could swim outside Indonesia’s safe waters and then be caught legally.