Abstract: Two groups of experiments were carried out in 1985 to study the eff-ect of depth on growth and mortality in culture of bay scallop. The results showedthat those cultured at 2 meters below the surface gave the best growth and lowestmortality. Those cultured at 1 meter and 3 meter depth grew poorer than that at 2meter while the bottom group was the poorest. The fouling on net-cages decreasedwith increase of depth. That at 2 meters the amount of fouling was about half ofthat at 1 meter, that at 3 meters was about 1/8 of that at 1 meter, and that on thebottom was merely 1/20 of that at 1 meter. Oysters (Crassostrea plicatula) attachedto shells of scallops in polyethylene net-cages at 1 meter depth were bigger in size andmore in number (about twice) than those at 2 or 3 meters depth. In hard plasticnet-cages, the oysters attached have about equal in size and number at any metersdepth. The dense fouling on the cage at 1 meter depth might effect growth of cultu-red bay scallop.