Bottlenose dolphins employ many tactics to hunt fish, like using their tails or swimming alongside fishermen. But a new study has discovered that the animals build mud rings to trap prey in the Caribbean — the first time it’s been seen in the region.
This hunting technique has only been seen up until now in the Florida Keys. It involves one dolphin from the pack kicking its tail near the seafloor to build up a mud ring. The fish get trapped in the ring and try to escape via the surface – but as they break through the water, the dolphins are ready to pounce.
Researchers at the Sarteneja Alliance for Conservation and Development first observed this fish-hunting tactic in the Caribbean at Chetumal-Corozal Bay, Belize.
Eric Ramos, the study’s author – PhD Candidate in Animal Behavior and Comparative Psychology in the Department of Psychology at The Graduate Center, City University in New York City, then searched Google Earth and found images of the mud ring.
To confirm that this was the same fish-hunting tactic used by bottlenose dolphins in Florida, Mr Ramos went to the US state to collect satellite imagery of mud rings there.
He told Utopian Magazine that he was amazed two groups of dolphins in different regions had found a similar tactic for trapping prey. However, the similar environments in the Florida Keys and Chetumal-Corozal Bay may contribute to dolphins using the same hunting method.
“This bay is very similar so it seems a strong case that they likely converged on this solution and learned to create mud rings to hunt fish in a similar circumstance, which is incredible to me that they would devise similar complicated tactics,” Mr Ramos said.
Although this was the first time researchers discovered that bottlenose dolphins in Belize, and also Mexico, created mud rings, Mr Ramos wasn’t surprised the animals developed the technique.
“You’d kind of expect the dolphins would do it but we hadn’t had evidence before showing that they could innovate a complex foraging tactic that’s so similar in different populations that are not close,” Mr Ramos said.
Despite the dolphins’ innovation, the impact of climate change on the world’s ocean may be detrimental to their hunting methods. Mr Ramos said the more specialized an animal is at hunting, the harder is it to deal with environmental change.
“They’re in a deficit in a future where climate change is shifting their bay because these dolphins are specialists for hunting fish against the shallows and if those fish populations are down, they won’t survive,” Mr Ramos said.