Rays are fish – a specific type of fish called elasmobranchs, which have skeletons made from cartilage and not bone. They are close relatives to sharks, which are also elasmobranchs. Rays are easily identifiable with flattened bodies, enlarged pectoral fins (that look like wings) which are fused to the head. There are over 600 species of rays and skates.
Mobulids are a genus of rays that include manta ray and devil ray species. All species in this genus must be in constant motion as they require movement of water over their gills in order to breathe.
The giant manta ray is the world’s largest ray species with a wingspan of up to 29 feet (nearly 9m). They are filter feeders and eat large quantities of plankton. Giant manta rays are migratory, and tend to be solitary but do meet other mantas at cleaning stations and to mate. Mantas have one of the highest brain-to-body ratios of any fish and have been shown to recognize themselves in a mirror.
Devil rays are the smaller (up to 5m/17ft), and less studied relatives of manta rays. They tend to be shy in the water making them more difficult to observe and study.
Large, deep-diving rays, like mantas and devil rays, help phytoplankton to grow. After diving down to feed, these rays return to the surface to defecate, which provides valuable nutrients from the deep to the plankton closer to the surface. These plankton are responsible for producing nearly half of the oxygen on Earth so manta and devil rays aiding in their growth, is actually helping all of us!
Even after death, large rays contribute to the marine ecosystem. When they fall to the ocean floor, they provide food to large communities of deep-sea scavengers of all kinds.
Additionally, manta rays contribute economically, especially in developing countries. Mantas generate approximately $100 million USD annually in dive tourism revenue worldwide.
All of the mobulid species are either endangered or vulnerable. Sadly, in 2020, the International Union for the Conservation of Nature (IUCN) announced that the conservation status of the giant manta ray (or oceanic manta ray) changed from Vulnerable to Endangered, a first for a manta species.
The largest threat to mobulids is commercial fishing: as a targeted species, as bycatch or as entanglement in large fishing nets and lines.
Mantas and devil rays are targeted for their gill rakers, thin cartilaginous filaments inside the mouth of the animal used to filter plankton from the water. In recent years, Chinese medicine has promoted the use of gill plates to treat coughs, respiratory illnesses and chicken pox. Since gill rakers filter plankton from the water, they are marketed to filter toxins and disease from the body. Unfortunately, there is no evidence to support these claims. Moreover, they are not a traditional medicine as their use began fairly recently and does not appear in any traditional literature.
Sadly, the growing demand for mobulid gill plates accounts for declines in some areas of up to 99%. Efforts to address overfishing of manta and devil rays, including prohibitions on fishing, are largely unsuccessful due to the high value of their body parts. While rays may account for just 3% of a boat’s total catch, they comprise nearly 50% of the income; fishers focus on rays rather than other commercial fish species.
Each year thousands of manta rays and tens of thousands of devil rays are caught as bycatch in high seas fisheries. Some of the most destructive forms of fishing (drift nets, longlining, and gillnets) are responsible for much of this. Manta and devil rays are especially vulnerable as they are migratory, covering vast distances of the open ocean where these fishing methods are used. Since these lines and nets do not discriminate between species that are caught, mobulids are frequently unintentionally caught and suffocate.
Manta and devil rays can get entangled in fishing lines and nets. Being so large, their gills, fins, or entire body can get wrapped up. Since they need to move to breathe, they attempt backward rolls to free themselves, often causing further entanglement. Fishermen have found that the process of releasing these large, odd-shaped fish can destroy the fishing net, reducing the incentive to do so.
It’s not just fishing gear that poses an entanglement threat to these animals. The use of boat mooring and buoy lines is increasing in coastal regions, populated by reef mantas. Unfortunately, mantas cannot always see these thin lines in time to move away. Since mantas need to continuously move to breathe, entanglements can lead to suffocation.
The amount of ocean traffic (from tourism, shipping, and transport) is increasing, as is the speed of the boats on the water. Mantas and devil rays, like other large marine animals that spend time at the surface, are increasingly vulnerable to boat strikes. Unable to avoid fast moving boats, rays can be struck by boat hulls and propellers.
Manta and devil ray species are particularly vulnerable to overexploitation because they produce only a single offspring every couple of years. They are among the slowest breeders of sharks and rays. Having evolved with few predatory pressures, high volume and high frequency reproduction were not a species necessity. Unfortunately, with the increase in pressure from humans, these species cannot adapt without time to recover. Bony fish, on the other hand, having always been hunted in large numbers by larger predators, may release hundreds of eggs at a time and spawn annually, or more frequently, allowing these species to recover more quickly.
Support Manta Tourism
Everyone remembers the first time they saw a manta ray or a huge school of devil rays. Snorkeling or diving these peaceful animals is an incredible experience. Tourists spend $140 million USD annually to see mantas in the wild. These tourist dollars put a higher dollar value on living animals than fished ones. This income incentivizes fishermen, local communities and governments to increase and enforce protections for these animals. Plan vacations around manta-tourism. Snorkel or dive with these animals. Choose responsible, locally owned operators who employ local staff to ensure that the community benefits from keeping these animals alive. Make sure your guides follow procedures and local codes of conduct intended to protect the animals. And be sure to share your incredible experience with others. Spread the word about these beautiful animals.
Make Responsible Seafood Choices
Responsible seafood choices can help to reduce manta and devil ray bycatch. Eat less seafood, choose local seafood, and only buy seafood caught using sustainable methods. Whether at the supermarket or a restaurant, consider not only the type of seafood you choose, but also the source. What methods were used to catch it? Ask for information and expect the store or restaurant to know. Seafood guides like Seafood Watch and the Good Fish Guide can help. Avoid supporting fisheries using destructive methods.
Support Organizations Protecting Manta and Devil Rays
There are many organizations working to increase awareness and protect manta and devil rays. They need your support. Many of these groups are very involved in lobbying governments and regulatory bodies. They often have petitions and seek public input — use your voice and spread the word.
Lobby for Greater Manta Protections
Stronger fishing regulations, marine speed limits in important areas, and the creation of more marine protected areas will all help to protect mobulids. Public perception and public pressure have a great deal of power, especially in the age of social media. Corresponding with lawmakers, news editors, and publicly on social media and through tourism channels, can make a difference. Vocal support for ray conservation from the public is essential to ensure these animals are protected. Your voice matters.
Manta Ray Fishing Ban, Indonesia
In 2014, Indonesia created the world’s largest manta ray sanctuary giving manta rays full protection across the country (six million square km). However, protection on paper and in practice are not always the same. Community support is necessary to enforce protection laws. Lamakera had been a manta fishing community for years and suddenly lost their livelihood. Several NGOs worked with the community to develop new sources of income and target other fish for food. Conservation is not just about laws and regulations but must be about people in order to succeed.
Giant Manta Protection, Peru
Peru has the world’s largest-known population of giant oceanic manta rays. In 2016, Peru prohibited manta fishing and mandated that mantas caught as bycatch be immediately released back into the ocean.
Manta Trust Marine Education Program, Maldives
Manta Trust, researched manta rays in the Maldives for years and have worked with the government to aid in their protection. To ensure lasting change, they are educating Maldivian children on the importance of their natural resources and the need to conserve nature. The goal is to create a personal connection between future generations and the ocean.
Training Artisanal Fishermen in Manta Ray Ecotourism, Peru
A Peruvian artisanal fisherman joined forces with Planet Ocean and started this movement. He recruited more fishermen to become conservation leaders in manta ray protection. The program provides microloans as well as training in business development, tourism infrastructure, ecotourism marketing and manta ray conservation. Now these former fishermen are leading manta ray tours and making money by protecting mantas.