Directed and incidental fishing
The two species of manta ray are currently threatened, listed as “vulnerable” in the Red List of the International Union for Conservation of Nature (IUCN). This organization states that the main threat is fishing manta rays incidentally and directed.
Directed fishing is, as the name refers, that which is focused on the capture of any particular species. Bycatch captures animals that are not the aim of the fishing industry and affects many species of marine animals around the world.
Manta rays are widely distributed in the warm waters of the Indian and Pacific oceans and to a lesser extent in the Atlantic, but their extent is fragmented, being possible to find regions of ocean without populations of them. In addition, the global population has a tendency to decrease. Needless to say that hunting contributes to increasingly harm the situation of these peaceful and beautiful animals.
Why hunting manta rays?
Overall, manta ray meat does not have a high commercial value as its flavor and texture are not very pleasing to the human taste. However, its capture has sparked significant trade in specific regions. The main reason? The strong demand for their gill rakers.
These structures are located in the gills and are the means of filtration they need to eat their food. For traditional Chinese medicine, they form a vital ingredient in the development of remedies that supposedly reduce toxins and improve blood circulation, which stimulates the immune system function. Other believed properties of these cartilaginous filaments are healing fertility problems, kidney problems, chickenpox and other common diseases.
Gill rakers are the most coveted part of manta rays and of rays of the Mobula gnus, and have good demand in the fisheries of the Philippines, Indonesia, Mozambique, India, Madagascar, Sri Lanka, Pakistan, Brazil and Tanzania. There are also directed fisheries in Mexico, Peru, Thailand and Somalia. According to data from the IUCN, in some areas over 1,000 giant manta rays (Manta birostris) and reef manta rays (Manta alfredi) are captured each year and in Mozambique about 50 individuals of Manta alfredi can be obtained along 50 kilometers of coast.
Fishing is done with harpoons and to a lesser extent with nets. It is easy to capture because they don’t usually swim at high speed and prefer to feed near the surface of the water. Fishermen throw their harpoons and suddenly when they catch them they bring them up directly to the boats; in Indonesia songs are often sung that according to their beliefs prevent them from escaping. It may be that they have to cut their bodies when still alive because they don’t properly fit on the boats. The gill rakers are then sectioned and stretch out to put under sun to dry. Know that, like some other remedies of alternative medicine, there is no scientific evidence that their consumption cure diseases. Apart from this, the popularity of gill rakers has increased while obtaining shark fins has become more difficult.
The meat, though less in demand, can serve for human consumption or as bait for sharks. Fresh meat is cut into strips, salted and hung to dry in the sun; occasionally it is used to feed animals. Areas such as the Philippines and the Gulf of California, where the manta ray population was once profuse, is now poor in individuals.
Due to their cephalic lobes and protruding pectoral fins, they are prone to entanglement in gill nets and trawls. When this happens they try to free themselves but only manage to entangle more getting dangerous wounds or dying smothered by the inability to properly pump oxygen-rich water.
Their conservation status indicates that they are endangered species. Would you consider not supporting their fishing?
