Bogota, Nov 18: Freshwater dolphins in the Amazon and Orinoco rivers, the two major rivers of South America, are at risk of extinction, a Colombian scientist has warned. After a 20-month expedition that included a dozen South American waterways, Fernando Trujillo, a Colombian marine biologist, found "a very large drop in the numbers" of these freshwater mammals.
Trujillo, who headed a study of rivers in Venezuela, Ecuador, Peru, Bolivia and Colombia, said: "I'm not saying there's an immediate danger of extinction of these species, nor the experience has been an apocalyptic vision, but in the absence of accords and controls on fishing there will continue to be risk and a decrease in the dolphin population of the region," the Colombian marine biologist was quoted as saying.
He said a team of 25 scientists took part in the expedition, travelling in special boats in each country and covering a distance of 4,000 kilometres. The experts studied the Meta River and a tributary of the Amazon in Colombia; the Orinoco River in Venezuela; the Napo, Yasuni, Lagarto and Cuyabeno rivers in Ecuador; the Marañon, Javari and Samiria rivers in Peru; and the Itenez and Ichilo-Mamore rivers in Bolivia. Trujillo attributed the falling number of dolphins in these waterways "to the proximity of large urban centres, where there is uncontrolled fishing".
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The biologist also attributed the disappearance of thousands of dolphins in some rivers to mercury contamination associated with gold mining, especially in Venezuela and Brazil.
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