University of Maryland Extension

Contained Culture

Water column leases (WCL) have become popular, mostly for producing high quality single oysters to be sold to raw bars. The oysters are usually set on ‘micro-chips’, or finely ground shell fragments, and must spend time in a nursery prior to being placed in containment gear and on grounds for growout. It is imperative that these ‘cultchless’ oysters be protected from predators for good survival. The oysters are often from specially bred lines and frequently are ‘triploids’, oysters that are manipulated so that they do not spawn. This provides high quality meats throughout the year.

Several types of contained culture gear are currently used in Maryland. Bottom cages sit on legs on the bottom of the lease with oysters in them. These can be a variety of sizes, usually from 4’x4’ to as large as 8’x8’ square, depending on the area, labor and tending vessel used. Midwater gear that is placed on longlines and resembles plastic cylinders is a new type of culture equipment that has been effectively deployed. Surface floats have been used for many years and range from traditional PVC flotation collars used to suspend culture bags across their frames to newer varieties with double-layer wire cages to insert culture bags into. These have removable end caps in floatation units that can be removed and the units sunk to the bottom in the event of icing or storm conditions.

Containment gear needs periodic cleaning from biofouling and the oysters are run through a drum that tumbles and sorts them during the cleaning process. Some growers include this equipment on specially designed vessels while others bring the animals ashore for servicing. Because routine servicing is carried out during warm summer months when biofouling is at its greatest, it generally involves higher labor costs during growout but the oysters get a higher price in the market because of size, consistency and meat quality.

Contained Culture Cost Analysis Publication

(PDF Document)

Contained Culture Cost Analysis Spreadsheet
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