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[Oyster Gardening - For Restoration & Education]
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[Oysters & Oyster Seed]

  1. How oyster seed are produced
  2. How to deploy your oyster seed

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Oyster Hatcheries

Oyster "seed" is an oyster that is transplanted to another location for the purposes of commercial grow-out or restoration. Seed can be produced from a hatchery or harvested from the wild. The type of seed you will start with in this program is "spat-on-shell" or cultched oysters produced from a hatchery.

In producing spat-on-shell in the hatchery, whole oyster shell is first dried out on land in order to remove organic material that could degrade water quality in the setting tanks. Shell is placed in plastic mesh bags and stacked in the tanks - river water is then added and heated to temperatures that will enhance the setting of free-swimming larval oysters. Once the oysters have attached themselves, metamorphosed and set, they are then referred to as spat. Spat are generally kept in the tanks for several days, then removed to a nursery area where tides and currents provide the water exchange necessary for growth and survival ("Producing Oyster Seed By Remote Setting" provides additional information).

Cultched oysters can exhibit rapid growth, sometimes reaching 25 mm (one inch) in two to three months after settlement. Growth is extremely variable and depends on the interaction of many water quality factors, especially, dissolved oxygen, salinity, temperature, and food availability.

To learn what you need to know about purchasing oyster seed, you should read "Purchasing Seed Oysters."

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Deploying Oyster Seed

Two mesh bags containing spat-on-shell are placed inside the Taylor float. The oysters can be kept in these bags until they have reached 8 to 12 mm (1/4 to 3/8 inches). Bags are then opened and the oysters are spread in a thin layer across the bottom of the float. If you let spat grow too large before removing them, they could begin growing through the mesh bag, which makes them difficult to remove and usually results in a significant number being damaged or destroyed. Oysters can also potentially grow through the mesh of your Taylor float, so you should shake the float to dislodge oysters whenever the float is removed from the water for maintenance.

Location of your floats is important. Oysters grow best when they are placed in areas with maximum water flow around them. Tie the float to a dock where there is good tidal flow. It is recommended to use two lines to tie the float between two pilings so it doesn't bang against the dock. Banging can cause the oysters to close their shells and stop feeding.

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[oyster shell button]Getting Started

[oyster shell button]Oysters & Oyster Seed

[oyster shell button]Oyster Care

[oyster shell button]Oyster Ecology

[oyster shell button]Oyster Garden Data

[oyster shell button]For More Information

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This page was last modified Monday, 30-Aug-1999 13:24:27 EDT

The Oyster Gardening Program is a cooperative effort of the Oyster Alliance
Chesapeake Bay Foundation ~ Maryland Sea Grant Extension Program
University of Maryland Center for Environmental Science ~ Oyster Recovery Partnership

This page is part of the Maryland Sea Grant Oyster web site.

For more information, report problems or provide comments, please contact webmaster@mdsg.umd.edu