Strange, pink, small-eyed freshwater dolphins glide through today鈥檚 turbid waters of the Amazon river basin. But they are fast approaching extinction.
The Amazon river dolphin (Inia geoffrensis), or 鈥渂oto鈥�, is one of the few remaining dolphins on the planet that are restricted to freshwater, with two other superficially similar species in south Asia.
at the University of Dundee in the UK and his colleagues have spent more than two decades studying the botos around Mamirau谩 Sustainable Development Reserve in the Brazilian Amazon. Using their wealth of long-term data, Martin and at the National Institute of Amazonian Research in Brazil calculated population trends.
Advertisement
The team used 22 years of survival and reproductive data on more than 650 dolphins to create a model that predicts the botos population in the coming decades.
鈥淲hen we first started this work, there were dolphins everywhere, and we thought of them as actually very abundant,鈥� says Martin.
But their model delivered a shock. 鈥淚t knocked our socks off,鈥� says Martin. 鈥淭he decline is far more profound than we had imagined.鈥�
In all six of their simulations, the number of dolphins is predicted to fall by at least 95 per cent in less than 50 years. The extinction of the boto may occur in just over a century.
In this part of the central Amazon,聽the botos鈥� precipitous decline is largely due to entanglement and drowning in monofilament gill nets, and people catching and using the dolphins as fish bait.
Martin says that the boto is treading the same path as the baiji (Lipotes vexillifer), a river dolphin native to the Yangtze river in China that is probably now extinct. 鈥淎ll of the true river dolphins 鈥� the ones that can鈥檛 get away from humans 鈥� they鈥檙e all going down the plughole.鈥�
Explore the rich biodiverse waters of the Azorian Islands Spot blue and sperm whales on a Discovery Tour
Botos were the most numerous among river dolphins and were assumed to be in a fairer condition, he says. 鈥淏ut the reality is, it鈥檚 devastating how fast they鈥檙e disappearing.鈥�
One change that could have a big impact on the dolphins鈥� chances would be increased enforcement of existing laws on gill net use, says Martin.
at the Federal University of Juiz de Fora in Brazil says the extinction prediction is 鈥渞eally alarming鈥�. But Frias argues that the central Amazonian dolphins may be experiencing challenges that don鈥檛 necessarily impact the entire range of the species.
鈥淚t is crucial to identify if there is population decline in other regions,鈥� she says.
Oryx
Sign up to Wild Wild Life, a free monthly newsletter celebrating the diversity and science of animals, plants and Earth鈥檚 other weird and wonderful inhabitants
