Može biti otežana i migracija u osiromašeni uzvodni tok, bilo zbog prepreka uslijed niskog protoka ili zbog nedostatnog poticanja riba na migraciju.
Where tank wagons have been refilled without having been previously cleaned out, the consignment note shall show, as total weight of goods carried, the sum of the weight of the new load and of the residual load, which will be the same as the gross weight of the tank wagon, less its registered unladen weightEurlex2018q4 Eurlex2018q4