Collector system for a net cage installation (40) that is used for farming of marine organisms, comprising a collector (10) placed in the water in an area below the net cage installation (40), where the collector (10) is freestanding anchored to the sea bed (38), and that the collector (10) comprises of a number of ribs (14) that can unfold and which are covered externally or internally with a canvas (12). The invention also relates to a method for the installation of a collector (10) below a net cage installation (40) that is used for farming of marine organisms.