Biologists and environmentalists warn of the risk for the populations of the river dolphins and caimans. They estimate that fishermen catch about 1.5 tons of catfish with a full-grown caiman as bait and about 300 kg with the meat of a full-grown river dolphin. The last-mentioned are particularly threatened according to Vera Silva, the coordinator of the river dolphin project of the Inpa (National Institute for Amazonian Research): The river dolphins become 35 to 40 years old, but reach only late the sex-ripe. The females bear in each case only one young after a gestation time of 11 to 12 months. An uncontrolled interference in the nature of the river dolphins can therefore cause a drastic reduction of the species.
To bait the catfishes the hunters cut the heads, fins and/or legs and tails off the river dolphins and caimans and use only their bodies without entrails. The catfish is a scavenger and well-known as a water vulture.
Brazilian fishermen earn converted 30 Cents per kilo of catfish sold in Amazonia. In Colombia, where it is called Mota, the catfish costs 6.30 Dollar per kilo approximately. According to the environmental agency the caimans and river dolphins are caught at night to escape controls. The mass slaughter happens in the rivers I, Japur and Juru, feeder rivers of the Rio Solimões, at the border to Colombia.