HUMAITÁ, Brazil — At dawn, 20 fishers received a tip that matrinxãs were swimming down the Aripuanã River toward the Madeira, the Amazon Basin’s largest tributary. It was their opportunity to interrupt a week of unproductive fishing in Novo Aripuanã, a municipality in southern Amazonas state, in the Brazilian Amazon. So, they divided themselves among three wooden canoes and went to the river. It was just a matter of waiting for the shoal, which swims on the surface, and throwing the net. At 11 a.m., with no sign of the matrinxãs (Brycon melanopterus), half of them gave up and, in the larger canoe, returned to the city. A fisher observed everything from a tip of land at that meeting of white and black waters in the Middle Madeira, while just ahead several pink river dolphins (Inia geoffrensis) and tucuxis (Sotalia fluviatilis) emerged to breathe while fish hunting. “Maybe the school doesn’t even get here, because the river is very dry,” Raimundo Dias told Mongabay. At the end of April, the Madeira Basin was transitioning from the wet to the ebb season. With the water level still high, fish group into schools and migrate from lakes, tributaries and igarapés (small streams) to feed on fruits, seeds and terrestrial invertebrates that fall into igapós (flooded forests) and in the Madeira flood plains. But for a decade, abrupt and frequent changes in river levels have disoriented migratory patterns. Scientists and fishers attribute these irregular pulses to the Madeira hydropower plants, two large facilities…This article was originally published on Mongabay
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