Giant manta rays are mysterious, breathtaking sea creatures that marine biologists and scientists have insufficient knowledge of regarding their movements, habits and ecological needs until they tracked six manta rays (four females, one male and one juvenile) for 64 days with GPS tracking devices.
The scientific data that were revealed from the GPS tracking system were important for marine biologists to prolong the survival of these gentle creatures who are now considered as “vulnerable” or nearing extinction by the International Union for the Conservation of Nature. Rachel Graham, lead author on the study and director of the Wildlife Conservation Society’s Gulf and Caribbean Sharks and Rays Program stated that, “Our real-time data illuminate the previously unseen world of this mystic fish and will help to shape management and conservation strategies for this species.”
Tracking data revealed that the giant manta rays traveled almost 700 miles during the two month period around the Yucatan peninsula, with some manta rays travelling more than 1, 100 kilometers. They spend most of their time around coastal areas abundant with zooplankton and fish eggs and that they prefer warm waters (78.8 – 86 degrees Fahrenheit) that are less than 50 meters deep. What concerned the scientists were their propensity to spend almost 90 percent of their time outside Marine Protected Areas like major shipping routes making them vulnerable to being run down by ships or getting entangled with nets or anchors.
The giant manta ray’s threat for extinction is caused by several factors: their slow reproductive cycle (one or two offsprings every one or two years); being chopped up by fishermen to use as baits for sharks; being hit by shipping boats or getting entangled in their nets or anchors and the great demand for their gill rakers.
Gill rakers are the thin filaments that manta rays use to filter their food from water. These body parts are dried and boiled and used in alternative or traditional Chinese medicines purportedly to boost the immune system and to cure chickenpox and even cancer. This has an increasing demand in the Chinese market and other markets for gill rakers which is a great cause for concern because it might lead to the giant manta rays’ overexploitation.
With the valuable data gathered from tracking the giant manta rays with GPS tracking devices, I hope that our esteemed marine biologists and scientists will be able to formulate management and conservation strategies that will protect and prolong the survival rate of this breathtaking and gentle sea creatures.