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Oyster Research and Restoration


Oysters were once a very abundant and cherished resource of the Harbor estuary, but by the early 20th century, sediment and water pollution and overharvesting had all but eliminated these once dominant creatures. While only a few small patches of oyster reef remain today, water and sediment quality has dramatically improved, making the restoration of the Eastern oyster (Crassostrea virginica) to NY Harbor now potentially possible.

For the past decade, the Hudson River Foundation has worked with partners to study, design, and implement oyster restoration techniques suitable for the diverse environs of the Harbor Estuary. Starting with small pilot projects in 2010, over the past decade, the Hudson River Foundation and our partners have completed several research and restoration projects across the estuary. Building from initial pilot projects of less than 1/10 of an acre, we’ve now completed several restoration projects larger than 5 acres. While progress so far has been encouraging, oyster restoration efforts in the HRE are still in the very early stages and more research is needed to refine and optimize the techniques and continue to build on the progress made to date.  

The Governor Mario M. Cuomo/New NY Bridge Project at Tappan Zee

    Partners: The Hudson River Foundation, the University of New Hampshire, Billion Oyster Project under the direction of AKRF, Inc.
    The Tappan Zee project represents the most successful oyster reef restoration project implemented in the Hudson River Estuary. The project surpassed all previous projects in terms of restored area and several metrics of early restoration success. Due to the location near the northern limit of oysters in the Hudson River, successful oyster restoration in this area depended on careful consideration of habitat parameters affecting oyster settlement, survival, and growth, which informed the selection of specific restoration techniques and locations. Sampling in October 2020, at the close of this study, indicated an estimated total of 5.8 million live oysters had colonized the substrates deployed across the three project sites. The new six acres of reef also provided substantial new habitat for other species, including benthic organisms, resident and transient fish, and additional filter feeding species (mussels and barnacles). As this study and the previous 3-year pilot study have demonstrated, the conditions at Tappan Zee are highly suitable for oyster restoration projects and additional and larger scale restoration projects near Tappan Zee are likely to be highly successful.

Governor Mario M. Cuomo/New NY Bridge Pilot Project at Tappan Zee

Partners: The Hudson River Foundation, the University of New Hampshire, Billion Oyster Project under the direction of AKRF, Inc.

The Tappan Zee Bridge oyster mitigation project was preceded by a 3-year pilot study. This study assessed the performance of three potential restoration substrates, 1) metal gabion cages containing oyster shells, 2) small Reef Balls (“Lo-Pro”), and 3) larger Reef Balls (“mini-bay ball” style), at several potential restoration sites. Performance metrics included oyster recruitment (attachment of oyster to substrates), oyster growth and survival, and the longevity and sustainability of the two different substrate construction techniques. The pilot study determined that Mini-Bay reef balls and shell-filled gabions provided effective substrates, and were chosen for the full-scale reef restoration efforts.