Marine researcher identifies new bottlenose dolphin subspecies

A marine researcher at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science has identified a new bottlenose dolphin subspecies found only in the eastern tropical Pacific Ocean. “While there is a common belief that all dolphin species are already known, improvements in technologies and methodologies are helping to reveal a greater biodiversity in more recent years,” said Ana Costa, Ph.D., a Rosenstiel lecturer specializing in marine mammalogy.

After examining and analyzing a series of specimens, Costa and collaborators of the National Oceanic and Atmospheric Administration, found that the new subspecies, called the Eastern Tropical Pacific bottlenose dolphin (Tursiops truncatus nuuanu), is smaller than other common bottlenose dolphins. These dolphins likely prefer deep offshore waters between southern Baja California and the Galapagos Islands, she added.

In this study, which began in 2016, Costa and her colleagues examined total body length and skull morphology of common bottlenose dolphin specimens that were collected in the Pacific Ocean and are archived in several museum collections in the United States. They used multivariate and clustering analyses to examine the level of differentiation among the bottlenose dolphin populations.

“We found two distinct morphological clusters: the new subspecies found in the eastern tropical Pacific (ETP) and the common bottlenose dolphins found primarily in the eastern and western North Pacific waters,” Costa said. “The ETP bottlenose dolphins might be differentiating due to the distinct environmental conditions in these waters, such as oxygen and salinity levels and temperature conditions.”

Reflecting on the study, Costa said that a greater understanding of marine mammal populations is vital for preserving and protecting different species and subspecies at a time of global warming. “The conservation and management of marine life should be an international priority,” she added.

The study, “Tursiops truncatus nuuanu, a new subspecies of the common bottlenose dolphin from the eastern tropical Pacific,” was published December 10, 2022 in the Journal of Mammalian Evolution.