The tucuxi is a freshwater dolphin of the Amazon basin, separate from the marine Guiana dolphin.
Its back is blue-grey, its belly is lighter, and its dorsal fin is low and triangular.
Researchers surveyed 15 rivers in the Amazon and Orinoco basins from boats, comparing tucuxi and boto. They combined nine years of records and consistent methods to estimate density and abundance for different rivers.
At the lower Purus River in 2012, tucuxi density was estimated at 17.1 animals per square kilometre. In the Japurá River, estimates were 2.19 boto and 1.79 tucuxi per square kilometre; in the Solimões, they were 1.01 boto and 1.34 tucuxi. Some confluences were hotspots, while estimates differed among rivers and basins.
An extinction-risk assessment has not been added yet.
The study identifies bycatch in fishing nets, fishing that uses dolphin meat as bait, pollution, and river modification as threats. The authors say that keeping river systems connected and measuring human impacts are important for conservation.