The larger species of shark, such as the great white, find the easygoing manta ray to be an inviting target. As an indirect effect of global warming, the docile manta rays often find themselves hunting in the same waters as their enemies, as they migrate in search of food. Manta rays can swim fast and even leap out of the water, but they are no match for these predators. Sharks have begun to hunt manta rays in lieu of their normal prey, which is becoming increasingly scarce.
Humans have hunted manta rays for their meat, cartilage, skin and gills in many parts of the world. Their dried brachial filaments (gill rakers) are harvested for use as ingredients in Chinese traditional medicine. The end product is a powder that is said to detoxify the bloodstream and clear skin rashes, although there does not seem to be any firm evidence to support this claim.
In many regions, such as New Zealand, pods of killer whales herd manta rays. The whales corral the rays by swimming around them in ever-tightening circles, until they have confined them to one area. This makes it easier for the whales to feed on them.
The fishing industry has gradually depleted many of the species that manta rays feed upon. Overfishing has caused manta rays to venture into deeper waters to search for food. It is in these deeper waters that manta rays are in danger of meeting up with sharks and other enemies.