Page "Manta ray" Paragraph 34

Manta rays are subject to a number of anthropogenic threats.

Unlike their bottom-dwelling relatives, mantas must swim constantly in order to flush oxygen-rich water over their gills, making them vulnerable to entanglement and subsequent suffocation.

Mantas cannot swim backwards, and because of their protruding cephalic fins, they are prone to being caught in trailing fishing line, nets, and even loose mooring lines.

Mantas will often attempt to free themselves by somersaulting, tangling themselves further.

In the case of loose, trailing line, it is possible for the line to cut its way into the fleshy appendages of a manta as it swims, eventually resulting in irreversible injuries such as loss of cephalic fins and damage to pectoral fins, or even death if the wounds are severe enough.

Similarly, mantas are often entangled in gill nets used in coastal and pelagic fisheries, resulting in suffocation and death in most cases.