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Manta Rays

Manta Rays are enormous! The largest can measure up to 7metres across from wing tip to wing tip and weigh in at around 2 tonnes! They have the largest brain to body ratio of any fish and are thought to be the most intelligent of all sharks and rays. These gentle giants are filter feeders, sieving the water with their specialised gills for tiny plankton. They are friendly, sociable and hugely important to marine ecosystems, but unfortunately they are also facing massive threats.

(Photo copyright Guy Stevens)

Manta Threats


Mantas are often accidentally caught and killed by indiscriminate fishing methods.


Generally the flesh of sharks and rays is not considered as good to eat as that of other bony fish so for centuries they have been avoided by fisherman. However as numbers of more popular species, such as cod and tuna, are depleted, some fishermen have started targeting Mantas. Due to its low quality, Manta meat is often dried and sold as animal feed for chicken and shrimp farms.

Gill Plate Trade

This is probably the biggest threat to Manta Rays. In recent years a new industry has been created, catching Manta Rays for their gill plates. Gill plates or rakers are the bits in their gills used for filter feeding. 

The reason these are in demand is for use in Traditional Medicine; it is claimed that they have medicinal properties and can heal anything: from asthma to heart disease, from chicken pox to cancer! However there is no scientific evidence to back up these claims. In fact these days many large marine species such as Manta Rays are often found to have dangerously high levels of mercury and other toxic chemicals in their bodies due to bio-accumulation of pollution; so consuming them could cause very serious health problems rather than cure them. 

Interestingly this demand for gill-plates is only very new and though retailers claim to be reviving a traditional remedy, there is no evidence of it in traditional literature. So it appears to have been invented as a marketing ploy in order to play on the fears of consumers and make more money.

Female Manta Rays

Female Manta Rays don’t start reproducing until around 15 years of age, their gestation period is over a year, they give birth to one baby at a time and may not have another for a few years. So Manta Rays are not a species that can withstand commercial fishing pressure as they cannot reproduce quickly enough to replenish their numbers. As such this sudden boom in Manta fishing is decimating populations around the world.