Oysters

Revised March 2022

Overview

The United States produces two major species of oysters, Crassostrea virginica (the Atlantic oyster or Eastern oyster) and the non-native Crassostrea gigas (Pacific oyster). The Eastern oyster, found primarily in the Gulf of Mexico (Gulf Coast) region and the Chesapeake Bay region, historically accounts for roughly 75 percent of total U.S. harvests. Oyster production occurs throughout the world, and a variety of species and production methods are in use. According to FAO figures, in 1952 global oyster aquaculture production surpassed wild harvests for the first time – with 306,930 and 302,526 metric tons reported, respectively. Aquaculture production has consistently exceeded wild oyster harvests since that time, and in 2019 accounted for 6,125,606 tons, compared to 133,984 tons of wild harvests.

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 oysters are supervised by harvesters who scrape the oyster beds periodically to reduce clustering. Debate continues as to whether this approach can be considered aquaculture. In the case of cultivated oysters, the traditional method involves transporting immature oysters to man-made beds where they are allowed to mature. In many parts of the world oysters are grown off-bottom on lines or in containers, and this approach is now being adopted in several parts of the U.S.

In the Northwest and Northeast, a significant amount of shellstock oysters are produced on cultivated beds, while in Gulf Coast waters, they historically have largely been harvested from wild reefs (Muth et al. 2000).  Following a series of man-made and natural disasters over the past two decades, interest in hatchery production and off-bottom oyster culture is increasing in the Gulf region, and a number of hatcheries are now operational.

National Marine Fisheries Service (NMFS) figures indicate in that in 2020, U.S. oyster landings totaled 19.9 million pounds (of meats), down from the 2019 figure of 29.3 million pounds.  Oyster landings in 2020 were valued at almost $187.2 million, also down from the 2019 figure of about $254.3 million. While a significant portion of this downturn can be attributed to pandemic impacts on traditional markets, it is unclear how quickly the industry will be able to recover as market conditions normalize. The Gulf Coast region harvested about 9.1 million pounds of oysters in 2020, followed by the Atlantic states with 5.6 million pounds and the Pacific coast region with 5.2 million pounds.

The Chesapeake Bay's oyster industry has seen tremendous declines over the past century. In 1950, a combined total of 29,953,500 pound of oysters worth $11.1 million were harvested from Maryland and Virginia. By 1990 the combined harvest had dropped to 4,515,113 pounds worth $15.9 million. Following all-time lows for production and value during the past two decades, harvests for Maryland and Virginia in 2020 totaled a mere 3,917,301 pounds, but the reported value of the harvest had climbed to almost $48 million. Millions of dollars have been spent on various initiatives to restore populations of the native Eastern oyster in the Chesapeake over the past several decades. Major factors cited for declining landings 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. 

Oyster fishermen and farmers in the Gulf of Mexico have battled the combined impacts of industrial pollution, red tides, bacterial and viral diseases, and hurricane damage for a number of years. While the regional harvest has remained fairly stable over the past five decades, yields have declined steadily in recent years, from 17.7 million pounds in 2017 to less than 9.1 million pounds in 2020. Again, pandemic impacts are probably responsible for some portion of this decline, but other factors apparently were involved prior to 2020.   

Hatcheries use broodstock that have been held on-site and conditioned for maturation and spawning, or wild-collected broodstock during the natural spawning season. Broodstock are induced to spawn through environmental stimuli (primarily temperature). Fertilized eggs develop into larvae, which are cultured primarily with algae (which must be cultivated on-site), and larvae are washed and graded every few days until they become “pediveligers.” These pediveligers are then provided with shell cultch on which to settle en masse, or they may be placed in specialized tanks with finely ground oyster shell particles on which they settle individually. Individually-set oysters are required for most off-bottom culture methods. A suitably sized hatchery can supply several to many oyster culturists, and since these larvae are produced in a hatchery setting, the option for raising triploid oysters can help offset some of the inherent equipment and labor costs.

Culturists eventually need to “plant” the oysters in a productive natural environment, since the cost of cultivated algae as a food source soon becomes prohibitive.  These seed oysters can be cultured on a prepared water bottoms with shell or other suitable substrate, in off-bottom gear, or in intertidal zones in mesh bags secured with an anchored line.  Off-bottom gear and intertidal culture both tend to reduce problems with predators and fouling organisms. 

Off-bottom grow-out of seed oysters involves specialized structures.  Common techniques include bags suspended from long-lines or on vertical “racks,” strings of oyster shell or other suitable substrate with set juvenile oysters hanging from rafts, stakes with attached oyster shells, lantern nets hung from floats, or mesh tubes rotated by currents.  The use of floating rigid cages that can be flipped over, holding multiple stiff-mesh bags of individual oysters, provides the opportunity for regular exposure of oysters to the air in such a way as to inhibit growth and survival of fouling organisms while oysters close their shells and wait patiently until they are re-submerged. All off-bottom methods are designed to take advantage of the food and oxygen available in the water column, while reducing problems with predators and sediment accumulation.  Under certain conditions, off-bottom culture can produce harvest-sized oysters in less than half the time required for on-bottom culture.

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 methods of harvesting, where tongs work like a pair of combination post-hole diggers and garden bow rakes, 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.

The 2018 Census of Aquaculture reported total domestic oyster sales of $284.9 million, with $134.4 million in Eastern oysters, $89.5 million in Pacific oysters, and an additional $61 million in other species. States with notable production included Virginia ($62.4 million), Washington ($55.8 million), Louisiana ($29.0 million), California ($28.7 million), Massachusetts ($21.7 million) and Oregon ($19.6 million).  

Marketing Considerations

Historically, there have been four main sectors in the oyster industry value chain: harvesters (including farmers), wholesalers, processors and retailers. Oyster harvesting includes wild and cultivated harvesting of mature oysters. Harvested oysters are generally delivered to wholesalers and processors; and in some cases, they are directly delivered to restaurants or other retail outlets. The wholesalers may repack the shell-stock 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.
 
The processing sector buys shell-stock 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 shell-stock oysters and place them in several different sizes and types of containers for sale to restaurants, retailers and other processors. Oysters for the half-shell market are sorted, graded and washed, and later placed in cardboard boxes and burlap sacks.

Processors typically sell oysters as fresh raw shucked, processed half-shell or as other value-added products such as smoked, cooked, canned and breaded oysters. 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.
 
Consumers perceive raw half-shell 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. In this respect, off-bottom culture holds an advantage. 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. They generally consume cooked oysters at home and consume both raw and cooked oysters (steamed oysters or oysters Rockefeller) in restaurants.

If you elect to produce oysters for alternative markets a number of factors must be considered. Markets must be available to accommodate your production when it is ready for harvest. If you will be farming on a large scale and selling to a wholesaler or processor, keep in mind that developing and maintaining committed relationships with both suppliers and buyers will be crucial. No matter what your scale of production will be, you will need to provide value through quality control, harvest scheduling and customer service. In turn your customers must also be willing to provide reliable outlets for your fish when you need to move them.

Accurate and detailed cost projections are essential when establishing an oyster farming business. Projected costs (variable, fixed, marketing and opportunity costs) must be compared to prevailing market prices for the sizes and quality of the oysters you intend to produce. Keep in mind economies of scale – a smaller operation will have higher per-oyster costs and will require a number of small-volume, local markets that are willing and able to pay higher prices.

When a small oyster operation loses a customer, alternatives may be limited or nonexistent. Your input suppliers (seed and equipment) must be reliable and trustworthy, even when larger customers are competing with you. Small scale oyster production may not be profitable without a competitive edge in local markets gained through accessibility, customer service and logistics. Nonetheless, any number of marketing campaigns can be developed with local retail partners ranging from in-store product demonstrations, to visits by local school groups, to targeted marketing.

Regulatory Considerations

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. The FDA’s 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, a voluntary group composed of members from FDA, state health regulatory agencies and industry.
 
Globally, many oyster fisheries continue to decline.  Aquaculture practices are increasingly cited as the only practical means to sustain supplies.  Innovations on the horizon include the use of genetically improved strains, increased off-bottom culture, and increased hatchery production of individually set seedstock.  Opportunities exist in many areas to develop sustainable aquaculture practices for both native and introduced oyster species, although regulatory issues may constrain industry development in some locations.   Other constraints involve the costs of constructing and operating hatcheries, conflicts with navigation in public waters, and the potential for catastrophic losses from pollution, hurricanes, red tides (and similar organisms), and diseases.  

Resources

• Annual Commercial Landing Statistics, Fisheries Statistics, National Marine Fisheries Service (NMFS).
• 2018 USDA Census of Aquaculture  National Agricultural Statistics Service

Revised by C. Greg Lutz, Louisiana State University Agricultural Center