Fifteen Years of Rhode Island Oyster Restoration: A Performance Evaluation and Cost-Benefit Analysis
Federal, state and local non-profit organizations have long recognized the ecological and socioeconomic importance the oyster, Crassostrea virginica, represents to coastal communities. Shellfish restoration programs in Rhode Island date to the early 1900s and have been making considerable progress and gaining popularity in the past decade. To better understand both short and long term performance of oyster restoration in Rhode Island a compilation of all oyster restoration activities from 2000 to 2015 was undertaken. Restoration performance was assessed by comparisons of growth, survival, disease and recruitment over eleven years in two distinct programs; Roger Williams University’s Oyster Gardening for Restoration (2006 - 2014) and the North Cape Shellfish Restoration Program (2003 - 2008). Mean costs of restoration were weighed against cumulative value of ecosystem services provide by oyster reefs. Over 26 million oysters, encompassing 6.6 acres have been seeded in thirteen distinct restoration sites in Rhode Island waters including salt ponds, tidal creeks and open coves in Narragansett Bay. Mean growth of oysters in restoration sites was between 30-50 mm annually with mean survival of 22% and 55% for year one and two+ oysters, respectively. Mortality varies among sites and appears to be driven largely by disease. Mortality outpaces recruitment at all monitored sites leading to a decline of the population once seeding has ceased, driving the need for continued restoration to maintain desired ecosystem services. A cost-benefit model indicates Rhode Island oyster restoration is not equitable in terms of ecosystem services provided, as the cost of restoration is higher than the cumulative value of ecosystem services provided by the oyster reefs, thus, questioning the economic feasibility of restoration and emphasizing the importance of proper site selection coupled with alternate management strategies.