Proper and frequent maintenance is essential for commercial success of a bottom culture system. No predator control is used in mussel culture. However, light plastic or nylon netting is commonly installed when clams are planted to control predation by crabs, drills, or rays. Nets used to control predators are monitored and cleaned on a regular basis to eliminate entrapped predators, repair holes, and remove fouling organisms. These enclosures may be purchased from commercial suppliers or built by the culturist.
Shellfish seed is put in the mesh bags or plastic boxes and sometimes placed on a rack.
As the seed grows, it is transferred to enclosures with increasingly larger mesh. A larger mesh provides better water flow, which delivers more food and oxygen, while removing waste. Most prefabricated units are about five square feet, but units over 30 square feet have been used. Units can be used in the nursery phase for both clams and oysters. However, clams must be transferred to the bottom after 20 millimeters for growout to market size.