Lahille’s Bottlenose Dolphin
(Tursiops truncatus gephyreus)
SCIENTIFIC CLASSIFICATION
TOP THREATS
CURRENT STATUS
SPECIES OVERVIEW
The Lahille’s bottlenose dolphin is a small and remarkable subspecies found only along the coasts of southern Brazil, Uruguay, and Argentina. Fewer than 400 mature individuals are thought to remain, making this one of the most at-risk dolphin populations in the world. Habitat loss, accidental entanglement in fishing gear, and mounting environmental pressures all threaten this small, isolated group, but focused conservation work can still change its trajectory.
SPECIES RANGE
Lahille’s bottlenose dolphins live only in the coastal waters of the southwestern Atlantic, sticking close to the shorelines of southern Brazil, Uruguay, and northern Argentina. They favor shallow bays, estuaries, and nearshore shelf waters, the same places where human activity tends to be most intense. Because their range is so small and fragmented, even localized threats can have an outsized effect on the population as a whole.
THE PROBLEMS
Life close to shore comes with real risks for these dolphins. Accidental entanglement in fishing gear, particularly gillnets used in shallow coastal fisheries, is one of the leading causes of death. Coastal development, pollution, and habitat degradation are wearing away at the feeding and breeding grounds these dolphins depend on. Add in heavier vessel traffic, underwater noise, and a changing environment, and an already small, isolated population faces mounting stress and a real risk of further decline.
WHAT WE ARE DOING AND WHY
To better understand this vulnerable population, NMMF scientists teamed up with researchers at Brazil’s Universidade Federal do Rio Grande and Kaosa to try something new: using epigenetics to estimate dolphins’ ages from previously collected skin samples. Epigenetics looks at subtle chemical changes that build up in DNA over an animal’s lifetime. One of the most useful indicators is DNA methylation, which shifts in predictable, age-related patterns. By reading these patterns, scientists can estimate how old a dolphin is without ever having to handle the animal.
Using a recently developed epigenetic aging “clock,” the team analyzed 51 skin samples from Lahille’s bottlenose dolphins in southern Brazil (22 females, 29 males) and found ages ranging from 1 to 45 years. Knowing the age structure of a population helps scientists understand its reproductive potential, survival patterns, and vulnerability to environmental stress. This information that lets conservationists make more informed, timely decisions to protect this at-risk subspecies.
These findings were published in Endangered Species Research in 2025, marking an important step toward understanding and protecting this population. 1
HOW YOU CAN HELP
Your support helps protect the Lahille’s bottlenose dolphin and other vulnerable species through Operation GRACE and NMMF’s science-driven research, veterinary expertise, and conservation action. Every gift supports health assessments, population studies, rescue and response efforts, and collaborative fieldwork with local experts, all aimed at understanding the threats that at-risk marine mammal species face and protecting the ecosystems they depend on.
