Scientists conducting the first-ever South American river dolphin census have sighted hundreds of dolphins, raising hopes about the survival of some of the endangered species’ populations.

The survey counted 520 dolphins — 321 grey (Sotalia fluviatilis) and 199 pink (Inia geoffrensis) — during a 294-kilometre voyage down the Amazon, Atacuari and Javari rivers in Colombia, Brazil and Peru.

According to the team of scientists —led by the Omacha Foundation, with support from the Wildlife Conservation Society, Whale and Dolphin Conservation Society and WWF-Colombia — the results obtained in previous expeditions helped confirm that the Amazon dolphin populations are in better condition than those surveyed in the Orinoco River.

“The river count showed that although the dolphins face various threats, such as pollution, they have been able to survive in the Amazon in Colombia,” said Sauo Usma, WWF-Colombia’s Freshwater Programme Coordinator.

“We have noticed a change in the places where they are found, rather than a change in the number of individuals.”

The overall aim of the survey is to gather data on one of the endangered freshwater species in the world in order to design a management and monitoring plan, as well as get to know the state of the rivers and watersheds of some of South America’s largest rivers.

In previous legs of the expedition the team recorded: 270 dolphins in Venezuela (June 2006); 40 in Ecuador (July 2006); 131 on Colombia’s Meta River (August 2006); and 818 in Peru (September 2006).

A fifth and last expedition is planned for Bolivia between May and June 2007.

“Once we complete the Bolivian part of the survey, we will finally have dependable results on the state of river dolphin populations in the Orinoco and the Amazon basins,” Usma said.

“More importantly, we will be able to consolidate the necessary resources to set in motion a conservation strategy for these iconic species.”