Oyster reefs are planted by DMF in select places. In addition to working with fishermen to find appropriate areas to plant cultch, DMF also utilizes a habitat suitability index (HSI) to ensure cultch reefs are planted in areas with appropriate environmental conditions. Areas chosen are often easy for fishermen to access and work on the reefs and meet important biologic and logistical criteria. For example, a chosen planting site should be in the proper salinity for oysters to live, and the bottom must be able to support the weight of the reef.
Materials used to construct the reefs must serve the main purpose of allowing a healthy population of oysters to settle and grow on it. Ideally reefs would be constructed out of oyster shell, however due to fluctuating availability of oyster shells other materials are often used in their place. Limestone marl and crushed concrete are excellent alternatives when oyster shells are unavailable.
To learn more about where, when, and how these reefs are built, please visit the interactive Cultch Planting Site Guide.
Cultch planted sites are open to oyster harvest when the oysters on them become legal size. Generally this occurs three years after they are planted. By harvesting oysters from these cultch planting reefs, some harvest pressure on naturally formed reefs is removed and helps to allow those natural reefs to recover.
Because oyster reefs are habitat for a large number of species other than oysters, the benefit of planting cultch goes beyond a few harvests of oysters. Oyster reefs attract many sportfish like flounder and sheepshead while serving as nursery areas for gag grouper and black sea bass. Additionally oyster reefs improve water quality because oysters are filter feeders and remove many nutrients from the water column. Oyster reefs have also been shown to help stabilize shorelines and protect against erosion by slowing wave energy and trapping sediment.
These benefits derived from the creation of oyster reefs do not disappear after the first harvest of oysters either; reefs planted over 30 years prior still are active habitat and fishermen report that oysters can still be harvested from these older reefs.