By Meg Sutton, Environmental Defense Fund
Oyster reefs in coastal estuaries around the globe have been degraded for the past 100-200 years due to a combination of overfishing, harmful dredging practices, decreasing water quality, sedimentation and oyster diseases.1 Many formerly productive reefs are now functionally extinct, and it is estimated that 85 percent of reefs have been lost globally.2 The majority of commercial oysters are currently sourced from only five eco-regions in the world, concentrated on the east coast of North America and the northern Gulf of Mexico.2 In Louisiana, restoration of oyster reefs has been proposed to both mitigate the decline in stocks and to secure a number of co-benefits which oysters provide. Such restoration has an associated cost which has some asking: How much is an oyster worth?
Restoration of oyster reefs in the gulf would impart several benefits to the region including increases in oyster and fish stocks, improved water quality, erosion control, storm attenuation and economic stimulus for local businesses. Each of these benefits has an associated economic value and should be factored into the decision to bring oyster reef restoration to scale.
The most readily apparent economic benefit of oyster reef restoration is an increase in, or maintenance of, primary oyster productivity. Louisiana is the leading oyster producing state in the U.S., supporting an oyster industry that generates $35 million in dockside value annually.3 Additionally, oyster reefs serve as refuge and feeding ground for many estuarine species including fish, mobile crustaceans and invertebrates. This ecosystem benefit is especially pertinent along the Louisiana coast, where oyster reefs are the primary three-dimensional habitats available. In Louisiana, 23 percent of annual marine fishing occurs over oyster beds, and these areas provide approximately $2 million (2003 dollars) in fisheries value annually for coastal Louisiana.4
Oysters are filter feeders, and this filtration notably reduces the turbidity and nitrogen loading of their surrounding water. Reduction of turbidity — the removal of suspended solids — has been shown to have a significant recreational value for boating and beach swimming. The willingness to pay for reduction in bacteria and oil, as well as improvement in water color for beach goers, was estimated to be $23.39 per person per year.5 In a study of the Choptank River in Maryland, the economic value of the nitrogen removed by an oyster over a ten-year interval was found to be greater than the dockside value of the oyster.6 In a separate analysis, an acre of healthy oyster reef was estimated to yield $3,000 in de-nitrification value annually.7
Additionally, the three-dimensional oyster reef structure attenuates wave energy, which can reduce erosion rates. Oyster reefs are generally understood to dampen wave energy by creating frictional energy between their rough outer surfaces and the wave. The associated economic value of wave attenuation is hard to determine, as it varies based on location. One factor to consider, however, is that the Gulf of Mexico has over 8,000 miles of shoreline that are at risk for erosion.8 Erosion rates and risk of flooding due to storm surge will continue to increase over time with global climate change, environmental degradation and subsidence of the area. If we choose to armor these shorelines, the current option is to install a bulkhead. Bulkheads can cost up to $1 million per mile, while oyster cultch placement — a common method for oyster reef restoration — can be completed for one-third of the cost.8
The industrial and commercial activity that would be generated by large-scale gulf oyster restoration will additionally boost the economy in the Gulf Coast and provide new job opportunities in the gulf and in 17 other states.9 Such restoration efforts would generally benefit small businesses, creating opportunities for local residents to both build new business and contribute to the sustainability of their region.
Restoration of oyster reefs may be necessary to maintain oyster landings in Louisiana, and it would also contribute to the sustainability of the region through ecological co-benefits, shoreline protection and economic stimulus. While these benefits may be difficult to generalize to a per-oyster dollar value, it is clear that the overwhelming co-benefits of oyster reef restoration in Louisiana should be considered in conjunction with the total cost of restoration.
1 Grabowski, J.H. & Peterson, C.H. Restoring oyster reefs to recover ecosystem services. Theoretical Ecology Series 281-298 (Elsevier Academic Press: Burlington, MA, 2007).
2 Beck, M.W. et al. Oyster Reefs at Risk and Recommendations for Conservation, Restoration, and Management. BioScience 61, 107-116 (2011).
3 Louisiana Department of Wildlife and Fisheries. Oyster Stock Assessment Report. (Baton Rouge, LA, 2010).
4 Henderson, J. & O’Neil, J. Economic Values Associated with Construction of Oyster Reefs by the Corps of Engineers. United States Army C (2003).
5 Freeman, A.M.I. The Benefits of Water Quality Improvements for Marine Recreation : A Review of the Empirical Evidence. 10, 385-406 (1995).
6 Newell, R., Fisher, T., Holyoke, R. & Cornwell, J. Influence of Eastern Oysters on Nitrogen and Phosphorus Regeneration in Chesapeake Bay, USA. The comparative roles of Suspension Feeders in Ecosystems 47, 93-120 (2005).
7 Piehler, M.F. & Smyth, A.R. Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services. Ecosphere 2, (2011).
8 National Fish and Wildlife Federation. Toward a Healthy Gulf of Mexico: A Coordinated Strategy for Oyster Restoration in the Gulf. 1-6 (2012).
9 Duke Center on Globalization, Governance & Competitiveness. Stokes, S., Wunderink, S., Lowe, M. & Gereffi, G. Restoring Gulf Oyster Reefs: Opportunities for Innovation (2012).