Tred Avon Restoration

Large-scale restoration efforts began in 2015 in Tred Avon sanctuary. The initial implementation phase of the restoration project is anticipated for completion in 2020, with a total of 130 acres of reef restored. Monitoring is underway to gauge success.

The restoration plan for Tred Avon may befound here.


The oyster metrics are quantitative evaluation criteria used to determine the restoration success of an oyster reef and tributary.

  • A successfully restored reef should have:
    • A ‘minimum threshold’ of 15 oysters and 15 grams dry weight per square meter covering at least 30 percent of the target restoration area at six years post restoration;
    • A ‘target’ of 50 oysters and 50 grams dry weight per square meter covering at least 30 percent of the target restoration area at six years post restoration;
    • Two or more oyster year classes present; and
    • Stable or increasing spatial extent, reef height, and shell budget.
  • A successfully restored tributary is one where:
    • 50 to 100 percent of the currently restorable oyster habitat (CROH) has oyster reefs that meet the reef-level metrics above. Restorable habitat is defined as area that, at a minimum, has appropriate bottom quality and water quality for oyster survival AND
    • 8 to 16 percent of historic habitat (Yates Bars), and preferably more, has oyster reefs that meet the reef-level metrics above


Three year and six year monitoring efforts are used to assess the oyster metrics for each reef. The first reefs to receive three year monitoring in the Tred Avon will be monitored in 2018. This monitoring report has not been published yet.



Tred Avon Restoration Reefs

Below is an interactive map with the restoration reefs in the Tred Avon Sanctuary. The legend and layers are located in the upper right hand corner. You can click on a reef to see more information. The information was last updated in 2018.

Restoration sites are identified as ‘seed only’ restoration (hatchery-produced spat-on-shell added to existing remnant reefs) or ‘substrate + seed’ restoration (adding reef-building substrate to the reef footprint, followed by planting with hatchery-produced spat-on-shell) or ‘premet’ (sites that already meet the Oyster Metrics target oyster density (50+ oysters per m2) and oyster biomass (50+ grams per m2) and did not receive initial restoration).