It has long been believed that manta rays migrate thousands of miles and travel across oceans. New data, however, reveals these rays are actually not as infected with wanderlust as we previously thought.
Oceanic manta rays, which are bigger than reef mantas and live in the open ocean, were thought by scientists to travel thousands of miles across the ocean, following the krill, plankton and small fish that the filter feeders eat, according to National Geographic. Other filer feeders like whale sharks travel this way.
But researchers employed satellite tags to track 18 manta rays around Mexico and Indonesia and found that oceanic mantas aren't actually epic travelers — in fact, they're practically homebodies.
The collected data revealed that 95 percent of the time, the observed manta rays both in Mexico and Indonesia stayed in patches of ocean as small as 140 miles across (tiny when you take into account that these pelagic creatures grow to be 23 feet wide and weigh 2 tons). The mantas were rarely observed leaving these zones.
The study is helping provide crucial information for conservationists.
"If you had a fishery that was drawing from the entire population of Indo-Pacific mantas, ... [killing] 10 [to] a hundred mantas a year wouldn’t be a huge number, necessarily," says Josh Stewart, a Ph.D. student at the Scripps Institution of Oceanography in San Diego and lead author of the new study. "But if there are these very local, isolated subpopulations, then you’re talking about removing half of the population in a year.”
Guy Stevens, the founder and chief executive of the conservation nonprofit Manta Trust, adds, "If we can see that there are discrete subpopulations within Mexican waters, that would enable Mexico as one country to protect breeding, sustainable pockets of these animals themselves." He explains, "That doesn’t require any international agreement. They can get on with it [and] protect these animals."
There's a lot more to learn about mantas' swimming habits, and how this affects how they eat. But this study alone is an important reminder of just how important scientists' work is in furthering our ability to protect vulnerable species.