Lahille’s Bottlenose Dolphin
(Tursiops truncatus gephyreus)
SCIENTIFIC CLASSIFICATION
CURRENT THREATS
CURRENT STATUS
SPECIES OVERVIEW
Lahille’s bottlenose dolphins are a distinctive and critically endangered subspecies found in the coastal waters of southern Brazil, Uruguay, and Argentina. With fewer than 400 mature individuals remaining, this small and isolated population faces severe threats from habitat degradation, fisheries bycatch, and increasing environmental pressures, placing it at high risk of extinction without sustained conservation action.
SPECIES RANGE
Lahille’s bottlenose dolphin is restricted to the coastal waters of the southwestern Atlantic Ocean, occurring primarily along the shores of southern Brazil, Uruguay, and northern Argentina. This subspecies favors shallow, nearshore habitats, including bays, estuaries, and continental shelf waters, where it overlaps closely with areas of intense human activity. Its limited and fragmented range contributes to its vulnerability, as localized threats can have significant impacts on the overall population.
THE PROBLEMS
Lahille’s bottlenose dolphin faces multiple, compounding threats throughout its limited coastal range. Accidental entanglement in fishing gear is a leading cause of mortality, particularly in gillnet fisheries operating in shallow nearshore waters. Coastal development, pollution, and habitat degradation further reduce the quality of critical feeding and breeding areas. In addition, increased vessel traffic, underwater noise, and environmental change place added stress on an already small and isolated population, intensifying the risk of continued decline.
WHAT WE ARE DOING AND WHY
In an effort to better understand this vulnerable population, NMMF scientists partnered with researchers at Brazil’s Universidade Federal do Rio Grande and Kaosa to apply innovative epigenetic tools to determine the ages of dolphins from 51 previously collected skin samples. Epigenetics is a method that detects subtle changes in DNA over time, and one key marker is DNA methylation patterns, which change as an animal ages. By measuring these patterns, scientists can estimate a dolphin’s age, offering a window into the population’s health and structure. Using a recently developed epigenetic aging clock, the team found ages ranging from 1–45 years.
Knowing the age of individual dolphins helps scientists understand the overall health of the population, including reproductive potential, long-term survival, and vulnerability to environmental stressors. This research provides conservationists with the information they need to make informed management decisions and enhance protection efforts for this at-risk species. A manuscript detailing these findings will be published in Endangered Species Research in the fall of 2025.
Acoustic Monitoring
Researchers have long used underwater recorders to detect vaquita clicks. Building on that foundation, we began developing smart acoustic buoys that can identify vaquitas in real time, relay data instantly, and alert teams to nearby vessels – creating faster, more effective protection for this critically endangered species.
Drone-Based Health Assessments
We initiated development of SEAHAWC, an AI-enabled drone designed to identify individual vaquitas, assess health, and monitor for illegal fishing activity, all without disturbing the animals. Training local community members in its operation will ensure lasting, locally led protection for vaquitas.
HOW YOU CAN HELP
Your support helps protect the Lahille’s Bottlenose Dolphin and other vulnerable species through Operation GRACE and the National Marine Mammal Foundation’s science-driven research, veterinary expertise, and conservation action. Donations directly support health assessments, rescue and response efforts, and collaborative fieldwork with local experts to better understand threats, improve survivability, and protect the river ecosystems these dolphins depend on.
