ZSL scientist Nadia Richman said:
“Freshwater cetaceans occupy some of the most densely populated and polluted river systems in the world. We need to make decisions about the best way to manage these species before another becomes extinct. However, these decisions need to be based on evidence which means we need methods that can detect changes in population size in the quickest time possible and for the least cost.”
The ability to detect changes in population size of a species helps to inform conservationists how fast a population is declining, and whether a conservation action has been effective in stopping a decline.
Previously it was believed that visual survey methods - reliant on conservationists spotting and recording surfacing dolphins - were the most cost-effective way of surveying the species. The study revealed that detecting the sound that dolphins emit using a method called a combined visual-acoustic survey, can improve the ability to detect population trends and reduce survey costs.
The study was undertaken by scientists from the Zoological Society of London (ZSL), Bangor University, the University of Chittagong in Bangladesh, the Wildlife Conservation Society (WCS), the Bangladesh Cetacean Diversity Project, and the Fisheries Research Agency of Japan recently in South Asian River dolphins in the rivers of Southern Bangladesh.
These findings have been published today (8th of May) in the journal PLOS ONE. Read the paper here.