At a time when mantas are obtaining star status with scuba divers, promising increased eco-tourism revenues, their populations around the globe are in peril. But mantas have not yet received global recognition as a species of concern. The World Conservation Union lists them as “Data Deficient”, meaning that there is inadequate information to make an assessment of their risk of extinction.
Manta populations are reported to be declining in Mexico, the Philippines, Indonesia, India, Sri Lanka, and other parts of Southeast Asia. No mantas were recorded in the Gulf of California (Mexico) in 2003, where a population of between 177 and 220 individuals had previously existed. Japanese sport divers report that manta populations at one site in the Sulu Sea declined by more than 60 percent over a seven-year period. Monitoring around Okinawa Island suggests schools of mantas have decreased in size, from 30 to 50 individuals in the 1970’s, to 14 or 15 individuals by the 1990’s.
In the Philippines fishermen are licensed to catch mantas using 1 km-long drift nets that extend to a depth of 30m. These nets are indiscriminate, also catching dolphins and endangered turtles which are then marketed as shark meat. A ban prohibiting the harvesting of mantas in Philippine waters was imposed in 1998, when it was discovered that entire populations of whale shark and manta ray had been decimated. However this regulation was short-lived and, 4 years later, was lifted due to a lack of resources to implement a sustainable management system, and political pressures from fisherman.
With widespread lack of regulation, catch data is not yet available for most of the areas where mantas are fished. However regional population declines have been recorded in several areas where mantas are fished, including the South China and Sulu Seas, the Philippines, Indonesia and on the west coast of Mexico. There is increasing concern about the sustainability of manta fisheries, but those who are economically linked to the industry oppose the regulatory processes that sustainable management will require.
A delicate balance exists between the economic well-being of coastal communities, the demand for traditional products such as Chinese medicines, and the protection of manta rays. Supporting local communities to manage and protect their own ecosystems and livelihoods may be the only viable solution in our rapidly changing world.
Conservation goes hand-in-hand with research and education.
To develop effective conservation strategies requires first understanding manta’s life history and migratory behaviour.
To ensure conservation efforts also deliver positive impacts for local communities requires first understanding the extent of target and non-target fisheries, the range of spiritual and cultural values that mantas provide, and the costs and benefits of extractive versus non-extractive uses.
To implement conservation and sustainable management practices requires first building a firm foundation of knowledge among the local populace and legislature.
Further information on manta migration patterns, population sizes and habitat preferences are necessary to support global management and conservation strategies. Greater awareness about the plight of manta rays is needed to catalyse change. Our members are helping to increase our knowledge of manta rays, and raise awareness for manta conservation.