May 12, 2012
First Satellite Study Of Tagged Manta Rays Exposes Hidden Habits
Conservationists from the University of Exeter in the UK, the Government of Mexico, and the Wildlife Conservation Society have completed a revolutionary study of Manta Rays, utilizing innovative satellite tracking devices.
The published study is the first to track the ocean´s largest ray, growing to twenty-five feet long, using satellite telemetry to ascertain the whereabouts of the endangered animal. The International Union for Conservation of Nature (IUCN) has listed the Manta ray as “Vulnerable” due to increased threats of accidental capture by fishers. Other threats include bait fishing, where fishers use the ray as bait for sharks, and the need for their gill rakers used in traditional Chinese medical practices.
This study was published Friday by online journal PLoS One authors including: Brenden J. Godley of the University of Exeter, Dan W. Castellanos of the Wildlife Conservation Society, and Francisco Remolina of the National Commission of Protected Areas, Cancun, Mexico as well as Lucy A. Hawkes of Bangor University, Bangor, United Kingdom, Matthew J. Witt of the University of Exeter, Rachel T. Graham of the Wildlife Conservation Society and the University of Exeter, and Sara Maxwell of the Marine Conservation Institute and the University of California-Santa Cruz.
Researchers placed satellite transmitters on the backs of four female rays, one male ray, and one juvenile ray over the course of thirteen days, just off the coast of Mexico's Yucatan Peninsula.
"Almost nothing is known about the movements and ecological needs of the manta ray, one of the ocean's largest and least-known species," Dr. Rachel Graham, chief author on the study and director of WCS's Gulf and Caribbean Sharks and Rays Program stated. She also said, "Our real-time data illuminate the previously unseen world of this mythic fish and will help to shape management and conservation strategies for this species."
Manta rays, like filter feeders such as whale sharks and baleen whales, will glide through multitudes of tiny plankton, acquiring their nutrients from the small creatures.
"The satellite tag data revealed that some of the rays traveled more than 1,100 kilometers during the study period," stated Dr. Matthew Witt of the University of Exeter's Environment and Sustainability Institute, also stating, "The rays spent most of their time traversing coastal areas plentiful in zooplankton and fish eggs from spawning events."
The manta ray, also known as the devilfish, is harmless to humans, although their bat like qualities gives them a sinister appearance. They have no stinger, unlike the more commonly known stingray and have the highest body to brain ratio of all rays and sharks identified. Typically, the manta ray will give live birth to one or two pups every one to two years.
The group of researchers found that the manta ray preferred to spend the majority of its time within 200 miles of the coastline, in Mexico´s territorial waters. Unfortunately, only 11.5 percent of these frequented areas are in marine protected zones, and most of the areas are actually major shipping routes, causing concern that ships could hurt the manta rays. They are decreasing in number in tropical ocean areas around the world, including the Caribbean.
Dr. Howard Rosenbaum, Director of WCS's Ocean Giant Program stated, "Studies such as this one are critical in developing effective management of manta rays, which appear to be declining worldwide.”