A new study has revealed that manta rays have social bonds and choose their friends. Researchers from the Marine Megafauna Foundation, Macquarie University and the University of Papua are the first to describe the social structure of manta rays in a study published in the journal Behavioral Ecology and Sociobiology.
In contrast to sharks and rays, reef manta rays move in groups at cleaning sites and feeding grounds in shallow waters. Over 500 of these groups were studied over five years in Raja Ampat Marine Park in Indonesia. At Raja Ampat, which is one of the most biodiverse marine habitats on the planet, two distinct but connected communities of manta rays were found living together. One group was primarily made up of mature females, while the other was a blend of males, females and juveniles.
“We still understand very little of how mantas live their lives, but we know they are socially interactive, and these interactions seem important to the structure of their populations. Understanding social relationships can help predict manta ray movements, mating patterns and responses to human impacts. That's essential for conservation and ecotourism efforts," said Rob Perryman, the lead author of the paper who is a Ph.D. student at Macquarie University and a researcher for Marine Megafauna Foundation.
Social network analysis
Social network analysis was used by scientists to reveal the network of various type of relationships in manta ray communities, ranging from passing acquaintances to long-lasting friendships. Even though mantas do not live in close-knit groups, the researchers found that females tended to have long-term bonds with other females, while males tended not to connect with many others—a disparity which could be due to distribution or different aims in reproduction.
"Like dolphins, manta rays are intelligent and perform collective behaviors such as foraging and playing,” said Perryman. “They are curious, often approaching humans, and individuals appear to have different personalities. It turns out that reef manta rays actively choose to group with preferred social partners.”
Finding the right balance when weighing protection and conservation of a species with ecotourism is important. “Knowing how mantas interact is important, particularly in areas where they are susceptible to increasing dive tourism,” said Dr Andrea Marshall, principal scientist and co-founder of the Marine Megafauna Foundation. “The increasing number of boats and scuba divers around reef mantas in Raja Ampat, particularly at cleaning stations, could break apart their social structures and have impacts on their reproduction.”