Pilcomayo River and incidences of massive fish kill – Bolivia

Photo credit: Rory Felix Mamani (Bolivia)

Review: Rory Felix Mamani and Abdel Rahman El Gamal (Founder of the website)

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The Pilcomayo River is a river in central South America which is about 1,100 kilometers long. The river originates in the eastern Andes Mountains in Bolivia which forms the upper basin of the river while the lower course forms about 800-kilometer international border between Argentina and Paraguay. The river has a total surface of approximately 290,000 km2, of which 31% belongs to Bolivia, 25% to Argentina and 44% to Paraguay.

Incidences for mass mortality of wildlife (fish, birds and mammals) along the Pilcomayo River have been reported whereas combinations of factors have been blamed for such crisis. Pollution especially from mining, sedimentation and drought are key causes for the mass kill incidences. In some parts of the river (e.g. in Paraguay), it is claimed that thousands of crocodiles and fish are dying trapped in the mud of a drying river.

It worth mentioning that the river basin is home to approximately 1.5 million people: one million in Bolivia, 300,000 in Argentina, and 200,000 in Paraguay. Economically, the Basin of Pilcomayo River is dedicated principally to agricultural activities as well as to fisheries. Bolivia has, within the context of the basin, about 12% of its national economy engaged in the area. The Pilcomayo River (a dry-land river) is characterized by its extreme inter-annual and inter-seasonal variability in discharge.

The inserted pictures show the mass fish mortality of the Pilcomayo River in Bolivia. This particular incidence occurs due the very fast draining of the river’s waters as required for the irrigation of agriculture lands. As a result, fishes could not follow the water and were trapped in small pools of water that gradually dried-up and turned devoid of oxygen leading to the mass kill of fish as shown in the photos. Incidences as such have serious impacts on sustainable fishery of the river due to hindering the natural spawning of affected fish as well as would affect the indigenous communities that rely on the river fishery in their livelihoods.

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