The Russian barges on the Danube according to a CIA report dated 17 May 1948

An item reported that the Russian merchant fleet on the Danube included around 550 barges of which the major part belonged to four types, namely with tonnages of respectively of 600, 900. 1.500 and 2.480 tons end each barge with an own number indicating the tonnage and a serial number. As example a barge with the No. 1265 had a tonnage of 1260 tons and as serial number 5 and the barge No. 659 had a tonnage of 650 tons and as serial number 9.

Source
The report was published on www.archive.org, document number CIA-RDP82-00457R001500460010-8