The collaborative project Following Whales documented the fourth complete migratory journey of a southern right whale since 2014. The protagonist was Sodium, equipped with a satellite transmitter in the Golfo Nuevo in September 2025, which returned to the Peninsula Valdés in May 2026 along with her calf Chloride.
This record adds to the previous cases of Papillon (2015), Electra (2022), and Aurum (2025), and represents the first complete journey of the 2025-2026 season.
Satellite technology and monitoring
The tracking was achieved thanks to state-of-the-art devices, designed to last for months and detach on their own without harming the animals. This season, 30 whales were monitored, of which four continue to transmit data accessible on the official portal.
The information obtained allows for a better understanding of the migratory patterns and to protect the essential marine environments for the species.
The journey of Sodium and Chloride
- Duration: 258 days.
- Distance traveled: 13,425 km.
- Route: from Peninsula Valdés to feeding areas on the platform and the continental slope, nutrient-rich zones known as “marine supermarkets.”
- Return: May 25, 2026, almost a year after the birth of Chloride.
These productive environments are key for the feeding of birds, fish, invertebrates, and marine mammals, reinforcing the importance of their conservation.
History of Sodium
Identified as No. 1099-99 in the catalog of the Whale Conservation Institute (ICB) and Ocean Alliance, Sodium has been known since her birth in 1999.
She was recorded in 2006, 2015, 2019, and 2025, always accompanied by calves. This tracking of more than two decades demonstrates the value of sustained monitoring.
Cultural transmission and survival
The journey provides essential information about the species’ life cycle:
- The mother regains energy in feeding areas.
- The calf learns the location of these zones during its first migration.
- This cultural knowledge determines future survival and reinforces site fidelity.
International collaboration
The project brings together institutions from Argentina, Brazil, and the United States, such as CESIMAR-CENPAT-CONICET, CIMAS-CONICET, FaCiMar-UNCo, Fundación Patagonia Natural, Instituto Aqualie, ICB, NOAA, University of Washington, Marine Ecology and Telemetry Research, UC Davis, and WCS Argentina.
The journey of Sodium and Chloride confirms the importance of satellite technology for the conservation of the southern right whale. Documenting these complete journeys allows for the identification of critical areas, the promotion of the creation of protected marine areas, and the regulation of human activities such as fishing, maritime transport, and hydrocarbon exploitation.
Source: WCS Argentina
