They were once commonly found on the lower Rio São Francisco in Brazil's Northeast Region (Nordeste).
According to Dr G. Gardner, in his Travels in the Interior of Brazil (1846), he was murdered in 1837 on the banks of the São Francisco River for charging too high for his medical assistance.
Nieuhoff was employed in Brazil to explore the regions between Maranhão and the São Francisco Rivers, made a particular study of the neighborhood of Pernambuco.
He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda (Sphyraena barracuda), the Chum salmon (Oncorhynchus keta) from the Kamchatka River in Siberia, and the curimatá-pacú (Prochilodus marggravii) from the São Francisco River in Brazil.
The fish Pygocentrus piraya often called the Piraya Piranha or San Francisco Piranha, and sometimes sold as the, Man Eating Piranha is a large, aggressive piranha from the São Francisco River basin in Brazil.
:For the river in Brazil, see São Francisco River.
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It forms the divide between the upper watershed of the São Francisco River and those of the shorter rivers which flow east into the Atlantic, including the Doce, the Jequitinhonha, and the Pardo rivers.
Minor changes were made to suit domestic politics (such as the Triângulo Mineiro from Goiás to Minas Gerais, the splitting of Paraná and ceding the south bank of the São Francisco River from Pernambuco to Bahia), as well as additions resulting from diplomatic settlement of territorial disputes by the end of the 19th century (Amapá, Roraima, Palmas).
Municipal water supply would receive priority over other uses, which would only be catered for only when the reservoir behind the Sobradinho dam on the São Francisco River, which produces much of the region's electricity, is nearly full about 40% of the time.