A method for the entrapment of water organisms, such as mussel seed, by means of a flexible elongate substrate (5), such as a rope or cable, which is located substantially in the body of water (9), comprising the steps of: - providing at least one in being located along the water surface of a water body extending elongated main line (4), such as a rope or cable, - it on every main line (4) fitting of rigid support members (3) extending distances of each other and which extend downwardly from said main line , - arranging the substrate (5) to the support members (3) to form substrate loops (6, 7) which extend into the body of water (9), - making deposition of the aquatic organisms on the substrate loops (6, 7).
