Indonesia protects mantas
On February 20th, Indonesia announced legislation to protect all manta ray populations within its nearly 6 million km2 Exclusive Economic Zone. The move not only establishes the largest manta ray sanctuary in the world, it helps safeguard a diving-tourism industry that annually generates millions in revenue.
Indonesia is home to both manta ray species, Manta birostris and Manta alfredi. Their gentle nature and spectacular size makes them favorites with recreational divers, but their slow reproductive cycle leaves them vulnerable to overfishing. Gestation may last over a year before females deliver perhaps just one live pup, sometimes 3–5 years apart. Indeed, a female may produce fewer than 20 offspring over her lifetime.
“Sadly, over the past 10 years, mantas have been severely overfished to supply the trade in their gill rakers as a traditional medicinal product in the Guangzhou region of southern China”, says Mark Erdmann, senior advisor to Conservation International's Indonesian Marine Program (Jakarta, Indonesia). “Yet, they are not even recognized as such by most practitioners.” The mantas' dwindling numbers led to their being placed on the Appendix II list of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Their new protection is in part due to recognition of the enormous economic value of these fish alive compared to their worth as a fisheries product. Last year, a study (PLoS ONE 2013; doi:10.1371/journal.pone. 0065051) showed that Indonesia's manta-diving-tourism industry was worth some US$15 million per year. “Over a manta's lifetime it could be worth $1 million to that industry”, explains Erdmann. “Compare that to the $500 a manta in a net is worth, then you can quickly see that this isn't only great conservation news, it's an economic no-brainer!”
Several species of cartilaginous fish, including whale sharks and sawfish, are also protected across Indonesia.
“An economic indicator that confirms a species' worth can help lawmakers make decisions that benefit their people in the long term”, comments Mary O'Malley (WildAid, San Francisco, CA). “Fishing such slow-reproducing animals will deplete populations quickly [leaving fishermen without manta fishing income]. Manta tourism income, however, is sustainable and brings income to other local businesses.”