For survival, dolphins share fish and a little more
Researchers have discovered some dolphin species have a lot more in common with humans than first thought. They gather in groups. They have strong social interactions. They share food. And sometimes, they get frisky.
Like most whales and dolphins, rough-toothed dolphins spend 80 percent of their time in the ocean depths—away from the prying eyes of researchers. It makes painting a good picture of how these dolphins behave and how they survive in a challenging environment such a mystery.
For six years, FIU Institute of Environment researcher Jeremy Kiszka and partners from Whales of Guerrero, City University of New York and Fundación International para la Naturaleza, studied rough-toothed dolphins that live about four hours north of Acapulco in the Bay of Potosi on Mexico's Pacific coast.
In January, researchers got lucky. Spotting a group of four rough-toothed dolphins, they launched an aerial drone.
They observed these dolphins sharing food. This time they were able to collect and analyze high definition videos of the behavior, which is known to exist in primates and bats but has rarely been documented in dolphins and whales.
Researchers also saw what happened next. Food sharing turned sexy for three dolphins. Well almost.
Two of them, named Fuji and Moby, took turns eating a fish for more than four minutes. Their friends, Blue and Pickles swam nearby.
Then things took a turn.
Blue swam up to Fuji. He lined himself up with her. He made a move. They both slowed their swimming. Yet, they never quite made a love connection.
Moby, meanwhile, kept eating as Fuji found her way back to him. He didn't share the fish again and ultimately devoured what was left. Then they lined up and made a brief encounter before swimming out of sight.
"It's very common for dolphins," Kiszka said. "Between foraging sessions, they will socialize a lot and one way to socialize is through sex. In highly social species such as dolphins, conflict is common, but it is often solved through sex."
For dolphins, sex goes beyond reproduction. Like sharing food, it strengthens their social bonds.
During this study, Kiszka and his colleagues also saw rough-toothed dolphins sharing food with members of their social group in 2016.
It looked almost like a relay. One rough-toothed dolphin caught a fish—likely a Pacific crevalle jack—ripped off a bit of flesh and dropped the fish so another dolphin could take a bite. They kept this up for at least 15 minutes until they were out of sight.
These observations in the Bay of Potosi suggest sharing is a common tactic rough-toothed dolphins use to survive in a hostile environment where food is scarce and predators abound.
As Kiszka and the team study the social lives of these dolphins, they realize how dolphins behave similarly to people as they look for ways to adapt to those challenges.
Kiszka and his colleagues will continue to examine the behavior of rough-toothed dolphins off the coast of Guerrero.
The study was published in the journal Marine Mammal Science.