by C. Greg Lutz, Pramod Sambidi and R. Wes Harrison, Louisiana State University Agricultural Center,
glutz@agctr.lsu.edu, psambil@lsu.edu, and rharrison@agctr.lsu.edu.
Profile updated May 2007 by Diane Huntrods, AgMRC, Iowa State University.
Overview
The United States produces two major species of oysters, including Crassostrea virginica (Atlantic oyster or Eastern oyster) and the non-native Crassostrea gigas (Pacific oyster). The Eastern oyster, found in both the Gulf Coast region and the Chesapeake Bay region, historically accounts for roughly 75 percent of total U.S. harvests. The Gulf of Mexico region, principally Louisiana, generally leads in oyster production followed closely by the Pacific region, principally Washington state. The Chesapeake region, principally Massachusetts, ranks third.
Production
Oysters are typically produced in one of three different ways: natural, managed and cultivated. Natural oysters grow and reproduce without human intervention and are often available for harvest by anyone with the appropriate licenses and permits. In contrast, managed natural oysters are supervised by harvesters who scrape the oyster beds periodically to reduce clustering. In the case of cultivated oysters, immature oysters are transported to man-made beds where they are allowed to mature. In the Northwest and Northeast, a significant amount of shellstock oysters are produced on cultivated beds, while in Gulf waters, they historically have been largely harvested from wild reefs (Muth, et al. 2000).
The Chesapeake Bay's oyster industry has seen tremendous declines over the past several decades. Harvests in Maryland have dropped to annual levels of 50,000 bushels or less, compared to 2.5 million bushels thirty years ago. During the middle of the last century, landings from Virginia waters reached levels as high as four million bushels annually, but recent harvests declined to roughly 20,000 bushels per year. This occurred in spite of literally millions of dollars spent on various initiatives to restore populations of the native Eastern oyster in the Chesapeake. A number of causes for the declines are clear, although how much can be attributed to any given factor is not. Major factors over the decades include overfishing, degradation of reefs by commercial fishing methods, deteriorating water quality, high sediment loads and the emergence during the last half-century of two devastating oyster diseases known as Dermo and MSX.
Industry Structure
Generally, there are four main sectors in the oyster industry: harvesters, wholesalers, processors and retailers. Oyster harvesting includes wild and cultivated harvesting of mature oysters. Harvested oysters are generally delivered to wholesalers and processors; in some cases, they are directly delivered to restaurants or other retail outlets. The wholesalers may repack the shellstock into sacks, boxes or bushels and sell them to other wholesalers or to processors. They may also sell them to restaurants or other retail outlets. They are generally sold in dozens, by the bushel bag or in bushel-fraction boxes.
Oysters are harvested in a variety of methods. In areas where oyster reefs are exposed by low tide, they are hand picked. In shallow areas, tongs are used to harvest oysters. Tonging is one of the oldest method of harvesting, where tongs work like a pair of post-hole diggers with handles that are at least 10 feet long. Oysters are also harvested by dredging from oyster boats, using metal baskets with rows of spike-like teeth. Oysters are harvested throughout the year, but the meat yield differs with the season. Oysters harvested in the winter yield roughly eight pounds of oyster meat per sack while oysters harvested in the summer on average yield six pounds per sack.
In the United States, oysters are harvested from both leased and public waters. With the collapse of wild oyster harvests in the Chesapeake Bay around the turn of the century, leases were legalized to encourage revitalization of the industry. Today, what harvests are still available in the Chesapeake come largely from private leases.
Louisiana’s oyster industry is primarily a lease-based industry, where oysters are cultivated on both public seed grounds and privately leased state water bottoms. Oystermen lease water bottoms from the state for $2.00 per acre per year (up to a maximum of 1,000 acres) and use that area for oyster culture. They typically dredge seed from public grounds and transport the seed to their lease, where the young oysters are allowed to grow for 1 to 2 years. The mature oysters are then harvested and packed into burlap sacks, which are tagged with information such as harvester name, date and location of harvest, before being marketed.
The processing sector buys shellstock oysters from wholesalers and other processors and, in some cases, they directly buy from harvesters. The oyster industry also involves vertical integration, where a fully integrated company may do everything from managing their own seed operation, through growing and harvesting, to shucking-sorting and delivering to wholesalers and retailers. Processing plants manually shuck shellstock oysters and place them in several different sizes and types of containers for sale to restaurants, retailers and other processors. Oysters for the halfshell market are sorted, graded and washed, and later placed in cardboard boxes and burlap sacks (Muth et al.).
Processors typically sell oysters as fresh raw shucked, processed halfshell or as other value-added products such as smoked, cooked, canned and breaded oysters (Muth, et al.). Oysters generally reach consumers live in the shell, as fresh, frozen or canned product, or further processed such as frozen and breaded. Shucked oyster meats are graded and sold according to size in 8-ounce and 12-ounce cups, or in pint, quart or gallon containers (Perkins 1995).
Demand
Consumers perceive raw halfshell oysters based on characteristics including appearance (size, shape, color), odor, flavor (sweetness and saltiness) and texture (firmness). They prefer cup-shaped oysters where the meat fits the shell. Color is less important to consumers, but unpleasant odors are regarded as an indication of spoilage. Consumers prefer fresh oysters, with a mild, salty flavor and no off-flavor, very tender and not mushy (Chen 1996). They generally consume cooked oysters at home and consume both raw and cooked oysters (steamed oysters or oysters Rockefeller) in restaurants.
Posadas and Posadas (2003) conducted a survey that indicated males consume more oyster meat than females. The survey also indicated that oysters are mainly consumed by people with education beyond the high school level. Major factors non-oyster consumers gave for not eating raw oysters was sliminess and appearance. Conversely, the major factor oyster consumers gave for eating raw oysters was flavor.
Import/Exports
The value of imported oysters continues to increase. The chief suppliers are Canada, China and South Korea. The United States imports both farmed and wild oysters from China and South Korea. The imported oysters are in live, fresh, frozen, dried, salted, brine, canned smoked and canned forms. Canned smoked oysters and canned oysters are the major forms of U.S. imports. Oyster imports are expected to keep increasing due to shortages from hurricane damage in the Gulf Coast region and from continued diseases in the Chesapeake Bay region.
Canada and China are the major importers of U.S. oysters. The United States exports oyster seed, as well as live, fresh, frozen, dried, salted and brine forms of oyster.
Regulatory
All oyster dealers in the United States must be certified under the National Shellfish Sanitation Program (NSSP) to market oyster products in interstate commerce. Processing plants that ship oysters are certified as interstate or intrastate shippers. Interstate certified shippers may ship oysters across state lines, while intrastate certified shippers may ship oysters only within their state borders. Interstate shippers are inspected and certified by individual states, which later provide lists to the FDA. The FDA uses this information to publish the Interstate Certified Shellfish Shippers List. Intrastate shippers are also inspected and certified by individual states, but those states maintain their own lists. State agencies involved in certification include departments of health, marine resources, agriculture, natural resources and wildlife and fisheries (Muth, et al. 2000).
The FDA’s National Shellfish Sanitation Program (NSSP) carefully monitors oysters from their growing waters through processing plants and finally to retail outlets. The NSSP maintains a Manual of Operations, which is routinely revised by the Interstate Shellfish Sanitation Conference (ISSC), a voluntary group composed of members from FDA, state health regulatory agencies and industry (Perkins 1995).
Emerging Developments and Outlook
Controversy has surrounded plans to evaluate an alternative, exotic species in efforts to revive the nearly collapsed Chesapeake oyster industry. A number of the issues currently being debated relate directly to aquaculture technology, its application and its environmental and socio-economic implications. Some stakeholders and regulators are primarily concerned with minimizing or avoiding adverse environmental impacts that may potentially accompany the introduction of an exotic species, while others point to the need to discard old approaches to restoration and try something new before the oyster industry disappears altogether.
Aquaculturists and researchers point out the possibility of producing large numbers of sterile exotic oyster seed to plant throughout the Bay as a way of avoiding natural reproduction. Under this scenario, if a major commercial harvest of oysters were restored, it would be reliant on continual seeding and a number of social and economic factors would come into play. The distinctions between harvests on public grounds as opposed to aquaculture production on private leases would be greatly exacerbated, and some traditional harvesters of public grounds cite the potential for the Chesapeake oyster industry to shift entirely to harvests from private leases. This shift would result in elevated production costs and the ultimate demise of the shucking industry. Some feel this would also eventually lead to increased vertical integration, with large packers and processors controlling extensive areas of leased bottoms, in addition to sources of seed and marketing channels.
The oyster industry in the Gulf region, particularly in Louisiana, was devastated by Hurricanes Katrina and Rita. In addition to the loss of oyster beds, the infrastructure for harvesting (boats), landing (docks), storage (ice houses) and marketing was badly damaged, causing oyster prices to rise. Prices are expected to remain high until oyster beds are recultivated and the necessary infrastructure has been rebuilt.
Sources
Chen, Y.P. 1996. Reduction and Management of Vibrio vulnificus in Gulf Coast Oyster (Crassostrea virginica). Doctoral dissertation. Louisiana State University. Department of Food Science.
Muth, K.M., D.W. Anderson, S.A. Karns, B.C. Murray, and J.L. Domanico. 2000. Economic Impacts of Requiring Post-Harvest Treatment of Oysters. Research Triangle Institute, North Carolina.
Perkins, E.B. 1995. Aquacultured Oyster Products: Inspection, Quality, Handling, Storage, Safety. Southern Regional Aquaculture Center.
Posadas, C.B. and R.A. Posadas. Consumer Preferences For Postharvest Processed Raw Oysters In Coastal Mississippi. Mississippi State University, Mississippi Sea Grant Extension Program and Mississippi Department of Marine Resources.
Profile created September 2003 and updated May 2007.