A whale census by face
The sheltered waters of Golfo Nuevo and Golfo San José, which define the Península Valdés, are the primary calving and nursing grounds for the southern right whale, Eubalaena australis. Each year, hundreds of these animals arrive to give birth and raise their young in the calm, protected bays. This annual gathering has enabled one of the longest continuous studies of any great whale.
Since 1970, a comprehensive photo-identification program has been underway, pioneered by researcher Roger Payne. The program leverages a unique physical trait of right whales: the callosities on their heads. These are patches of thickened, keratinized skin that are present from birth and form patterns unique to each individual. While the callosities themselves are dark, they appear white or yellow because they host dense colonies of small crustaceans called cyamids, or "whale lice," which feed on the whale's skin.
By conducting annual aerial surveys and collecting photographs, researchers can reliably identify and track individual whales throughout their lives. This has created a detailed, multi-generational database managed by organizations like the Instituto de Conservación de Ballenas and Ocean Alliance, which now contains the life histories of more than 5,000 individual whales. The 50-plus years of data show the population's growth, health, and social structures.
Biology of the bay
The southern right whale population was driven to the verge of extinction by commercial whaling, which targeted them for being slow swimmers that floated after being killed. After receiving international protection in 1937, the population began a slow recovery. The group that gathers at Península Valdés is a success, showing a consistent growth rate for decades. The current population is estimated at around 4,700 individuals.
Adult females, which can reach 15 meters in length and weigh up to 47 tonnes, arrive here after a year-long gestation period. They give birth in the warm, shallow waters that offer protection from predators like orcas and reduce energy expenditure for the newborn calves. Calves are typically born between June and mid-September. They nurse for about a year, consuming hundreds of liters of rich milk daily.
The whales' presence has turned the region into a center for regulated whale-watching tourism. Puerto Pirámides is the only port in Argentina licensed for boat-based whale watching tours. The entire peninsula was designated a UNESCO World Heritage site in 1999, recognizing its importance for marine mammal conservation.