First observations on annual massive upstream migration of juvenile catfish Trichomycterus in an Amazonian River.

Following flooding peaks in the Beni River, a massive upstream migration event involving juvenile pencil catfish ( Trichomycterus barbouri) or chipi chipi is described for the first time. The annual migration begins in the floodplains of the Beni River, where enormous schools of juveniles form to travel upstream through the straits of the last foothills of the Andes into Andean foothill forest streams and rivers. Observations and local knowledge suggest a migration distance of at least 370 km over an average of 32 days in February and March with an average speed of 12 km/day. The migrating juveniles weigh less than 0.38 g and measure less than 33 mm in standard length. As such, considering body length and body weight to distance travelled ratios they are one have one of the greatest migration efforts of any freshwater fish. Local people harvest juveniles across the migration route, but especially in Rurrenabaque, where they are considered a seasonal dish. This scientific revelation highlights the Amazon as a place where natural phenomena are still being discovered, described and documented in an era when hydroelectric infrastructure threatens the ecology of many aquatic ecosystems. [ABSTRACT FROM AUTHOR]