Manta rays drive global conservation efforts | Global Ideas | DW | 08.04.2014
  1. Inhalt
  2. Navigation
  3. Weitere Inhalte
  4. Metanavigation
  5. Suche
  6. Choose from 30 Languages

Global Ideas

Manta rays drive global conservation efforts

Manta ray populations around the world have declined in alarming numbers. Hitting the sweet spot between conservation and commerce may hold the key to the survival of these mysterious marine species.

With their languid tropical waters and coral reefs teeming with sea life, the Maldives are a major tourist hotspot. European and Australian divers disembark by the planeload in the capital city of Malé, drawn to the island nation encompassing 1,192 islands and 26 reef atolls in the vast remoteness of the Indian Ocean.

One of the star attractions here are manta rays. In fact, the Maldives are one of the few places on earth where the charismatic creatures survive in large numbers. Once prevalent in tropical and subtropical waters throughout the vast expanse of the Pacific, Atlantic and Indian Oceans, manta rays are in danger of being wiped out.

As the fishing industry races to meet the rising global demand for seafood, manta rays are inadvertently killed in fishing nets as bycatch and hunted for their gill rakers for use in Chinese health tonics.

Overfished and under-studied

In Mozambique, where some of the highest densities are found, manta ray populations plummeted by 80 percent in the last decade. Steep declines have also been recorded in India, Indonesia and Sri Lanka, and they have all but disappeared from the Sea of Cortez in Mexico, where manta rays once thrived.

Guy Stevens, a PhD candidate at the University of York and founder of the Manta Trust, a UK-based charity focused on marine conservation, has spent much of his adult life studying manta rays in the Maldives. Stevens and his team have identified 3,300
individual manta rays and catalogued their behavior for well over a decade.

Manta-Rochen in Mikronesien

Manta rays are a huge draw for tourists

"I consider them (manta rays) to be the canary in the coal mine," Stevens said. Manta rays are indicators of the health of the reef ecosystem, he explained. For reasons that remain unknown, the manta ray population inexplicably stopped reproducing for a period of three years in the Maldives. Stevens wants to unravel this mystery, in the hope of creating a comprehensive conservation strategy.

According to conservationists, the size of the global manta ray population remains a mystery. However, this much is known. They are slow to mature, corresponding to an age of 8 to 10 years, they are believed to live for at least 40 years or more and are slow to reproduce, giving birth to a single pup every 2 to 5 years. These traits make them extremely vulnerable to overfishing.

In 2011, the International Union for Conservation of Nature (IUCN) determined both species of manta ray, Giant Manta (Manta birostris) and the Reef Manta (Manta alfredi) vulnerable to extinction globally.

Rock stars of the reef

But there are a few things that could yet ensure the creatures’ survival. Once feared as ‘devil fish' due to prominent hornlike fins and their enormous bulk, mantas are now respected for the income they generate.

According to the 2011 report “Ray of Hope” published by the conservation group WildAid, they are worth far more alive than dead. Over the course of a lifetime, each manta generates as much as $1 million in revenue for the tourism economy. That helps boost the profits of dive operators and high-end resorts that provide employment to locals.

A mural of a manta ray in Colombo, Sri Lanka (Photo: Aaron Glasson/Celeste Byers/Simon Blackfoot/ Pangea Seed)

Grassroots activist group Pangea Seed brings sea creatures to the surface, creating vivid conservation-themed murals

Despite their ominous appearance, observers describe mantas as social creatures that seem genuinely curious about humans. Time and tide permitting, they swoop upon coral reefs, feeding on plankton. Their acrobatic displays and gentle demeanor add to their allure, making them charismatic stars of the reef and valuable attractions for recreational divers craving new experiences in exotic locations. This fondness for manta rays is a lifesaver and could prove to be a valuable conservation tool.

Caught between commerce and conservation

For the people of the Maldives - whose livelihoods depend on tourism and fishing - manta rays occupy a sweet spot between commerce and conservation. So much so that subsequent administrations have taken steps to ensure their protection. In 1995, government officials banned the export of mantas and manta ray products, halting what could have been a disastrous trade in the species.

Local fishermen, who depend on the natural bounty of the reef for their incomes, also have to follow regulations. Net fishing is not permitted in territorial water to ensure that large marine species don’t wind up in fisherman's nets as bycatch. In addition, local fishermen must use poles and fishing line to sustainably catch tuna.

In 2009, Maldivian officials declared Hanifaru Bay, a renowned dive site and manta hotspot, a marine reserve. Intended as underwater wilderness parks, marine reserves (often called fishing no-take zones) are designed to provide safe havens for sea life, further insulating manta rays and other marine species inhabiting the bay from exploitation.

As of September 2014, manta rays join five species of shark given a new
layer of protection under CITES
, the international treaty governing the
trade of endangered wildlife. The aim is to ensure that manta ray fisheries are both sustainable and legal on a global scale.

In Sri Lanka, fishing boats arrive with the days catch of manta (Photo:

Manta are increasingly hunted and sold for their gill rakers

In response, the Indonesian government recently declared all of its territorial waters off limits to manta fishing. The Manta Trust began an online petition urging supporters to encourage the Maldives government to expand marine reserves protecting manta rays.

More protection needed

Despite the positive steps taken, evidence suggests the future does not bode well for manta rays. According to a recent IUCN report, 25 percent of the world's sharks and rays face extinction, with large-bodied species living in shallow water at the greatest risk.

"Unless we do something about it, there's a high likelihood their declining trajectory will eventually lead to their extinction," Nick Dulvy, co-chair of the IUCN’s Shark Specialist Group and a professor of marine ecology at Simon Fraser University in Canada, said of sharks and rays.

The reduced numbers of manta rays correlate to the changing tastes of consumers in Asian markets. Over the past 15 years, fishermen hunted mantas for their gill rakers, the organ they use to filter food.

To a large extent, people eking out an existence in remote fishing villages in southeast Asia supply the demand for natural products sold in regional markets in the coastal cities of China. The harvesting of manta rays is one small part of a vast network of merchants and traders operating in Sri Lanka and throughout the Indo-South Pacific region.

"The fingers of commerce reach out to the remotest corners of the world," Dulvy said.