Oyster farming is an aquaculture (or mariculture) practice in which oysters are bred and raised mainly for their pearls, shells and inner organ tissue, which is eaten. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula [1] [2] and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century. [3]
Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula. [4] With the Barbarian invasions the oyster farming in the Mediterranean and the Atlantic came to an end.
In fact, the Romans were the very first to cultivate Oysters. The Roman engineer Sergius Orata is known for his innovative ways of breeding and commercializing oysters. He did this by cultivating the mollusk with a system that could control the water levels. [5]
In 1852 Monsieur de Bon started to re-seed the oyster beds by collecting the oyster spawn using makeshift catchers. An important step to the modern oyster farming was the oyster farm built by Hyacinthe Boeuf in the Ile de Ré. After obtaining the rights to a part of the coast he built a wall to make a reservoir and to break the strength of the current. Some time later the wall was covered with spat coming spontaneously from the sea which gave 2000 baby oysters per square metre. [6]
The Ancient Romans started farming the Thames Estuary in Hampton-On-Sea, or Kent, England from the 1st Century to approximately the 4th Century. They would export the oysters back to Rome and throughout the Roman Empire. On July 25, 1864, The Herne Bay Hampton and Recuiver Oyster Fishery Company moved into the area to start oyster farming. In the 1870s the oyster trade suffered from overfishing and sent the industry into a decline. This caused the government of the United Kingdom to pass the 1877 Act to solve the problem. This act prevented the sale of dredged oysters from the months of June through August, and freshwater pond oyster sales from between May and August. A couple of years later the company closed its doors and all the assets were sold by 1881, closing the oyster farming in the Thames Estuary area in England. [7]
Another place in England that is famous for its oyster fishing is Whistable. The area's “kentish flats” have been used since the Romans started. The oysters would get shipped to Italy, where Roman Emperors would pay for them by their weight in gold. [8]
Commonly farmed food oysters include the Eastern oyster Crassostrea virginica, the Pacific oyster Crassostrea gigas, Belon oyster Ostrea edulis, the Sydney rock oyster Saccostrea glomerata, and the Southern mud oyster Ostrea angasi.
Oysters naturally grow in estuarine bodies of brackish water. When farmed, the temperature and salinity of the water are controlled (or at least monitored), so as to induce spawning and fertilization, as well as to speed the rate of maturation – which can take several years.
The first step to cultivating oysters is conditioning broodstock. Broodstock are the "parent" oysters that will provide gametes for larvae. Oysters in the wild are only "ripe" with gametes for a short window. All of the oysters in an area will spawn at the same time to increase the chances that their gametes meet and fertile larvae are produced. To ensure ripe oysters for spawning throughout the season, some growers choose to keep mature oysters in a separate system where the farmer can manipulate the temperature and food within the system. While a recirculating system can be used, a flow-through system is generally better because the natural diversity of phytoplankton is a better diet for conditioning oysters. [9] By setting up this separate system, the farmer can mimic the transition from winter to summer quicker than real-time, and essentially convince the oyster that it is time to spawn whenever the farmer needs more larvae.
When the farmer actually wants to spawn the oysters, they will put a batch of oysters in a tray and rapidly heat and cool the water to induce spawning. It is important to have a large number of oysters, because it is impossible to tell if an oyster is male or female from its outer appearance. Once the oysters start to spawn they can be picked up and placed into their own separate containers until they have released all of their gametes. Eggs and sperm can then be mixed together to fertilize. [10]
Larvae tanks should be cleaned and disinfected before putting water in the tanks. Water quality should be tailored for the particular species, but most larvae will generally grow faster in warmer water. After the fertilized eggs and beginning-stage larvae have been added to the tank, they should be fed filtered or cultured algae daily, and have their water changed every-other day. This ensures no pathogens or foreign organisms enter the system and compete with or eat the larvae, and their water quality stays pristine to encourage growth. This is the most fragile stage of an oyster's life history. [11]
After about two weeks an oyster will be ready to set. They will develop a small, round discoloration called an eyespot despite not being used for seeing. Their muscular foot will be visible under a microscope. At this point, the larvae can be put in a system with a variety of cultch options. The best cultch is usually full or ground up oyster shell because oysters are naturally attracted to other oyster shell to ensure their future reproductive success. [11] After the larvae settle, they are considered "spat."
Three methods of cultivation are commonly used. In each case oysters are cultivated to the size of "spat," the point at which they attach themselves to a substrate. The substrate is known as a "cultch" (also spelled "cutch" or "culch"). [12] The loose spat may be allowed to mature further to form "seed" oysters with small shells. In either case (spat or seed stage), they are then set out to mature. The maturation technique is where the cultivation method choice is made.
In one method the spat or seed oysters are distributed over existing oyster beds and left to mature naturally. Such oysters will then be collected using the methods for fishing wild oysters, such as dredging.
In the second method the spat or seed may be put in racks, bags, or cages (or they may be glued in threes to vertical ropes) which are held above the bottom. Oysters cultivated in this manner may be harvested by lifting the bags or racks to the surface and removing mature oysters, or simply retrieving the larger oysters when the enclosure is exposed at low tide. The latter method may avoid losses to some predators, but is more expensive. [13]
In the third method the spat or seed are placed in a cultch within an artificial maturation tank. The maturation tank may be fed with water that has been especially prepared for the purpose of accelerating the growth rate of the oysters. In particular the temperature and salinity of the water may be altered somewhat from nearby ocean water. The carbonate minerals calcite and aragonite in the water may help oysters develop their shells faster and may also be included in the water processing prior to introduction to the tanks. This latter cultivation technique may be the least susceptible to predators and poaching, but is the most expensive to build and to operate. [14] The Pacific oyster M. gigas is the species most commonly used with this type of farming.
During the nineteenth century in the United States, various shallow draft sailboat designs were developed for oystering in Chesapeake Bay. These included the bugeye, log canoe, pungy, sharpie and skipjack. During the 1880s, a powerboat called the Chesapeake Bay deadrise was also developed.
Since 1977, several boat builders in Brittany have built specialized amphibious vehicles for use in the area's mussel and oyster farming industries. The boats are made of aluminium, are relatively flat-bottomed, and have three, four, or six wheels, depending on the size of the boat. When the tide is out the boats can run on the tidal flats using their wheels. When the tide is in, they use a propeller to move themselves through the water. Oyster farmers in Jersey make use of similar boats.
While oysters themselves can be very beneficial to their environment, the farming of oysters and other shellfish is not necessarily restorative environmentally. However, it does hold promise for relieving pressure on land-based protein sources. [15] Production of land-based protein sources can be detrimental to the earth environment as they generate a significant amount of greenhouse gases. Oysters, however, produce little to no greenhouse gases, and the difference in emissions between wild oysters and farmed oysters is negligible. The oysters themselves do not produce any methane, one of the most potent greenhouse gases, and just a very minimal amount of nitrous oxide and carbon dioxide. [16] [17] Restoration of oyster populations is encouraged for the ecosystem services they provide, including water quality maintenance, shoreline protection and sediment stabilization, nutrient cycling and sequestration, and habitat for other organisms. [18]
There has been a decline in oyster population due to extensive factors such as climate change and overharvesting of wild populations. Because of this, oyster reef restoration has been significant in the past decades, and a native Olympia oyster restoration project has been implemented in Liberty Bay, Washington. [19] This project uses a "Habitat Sustainability Index (HSI)" to assess the ecological impacts of the restoration. The HSI also measures the benefit to the oyster population as well. [20] Oyster farming in the Chesapeake Bay has minimal or even positive impacts on the surrounding environment, [21] and numerous oyster restoration projects are underway in the Chesapeake Bay. [22] The Chesapeake Bay Foundation started working in conjunction with the Smithsonian Institution in 2022 to revive the oyster population that was disrupted due to the poor health of the water quality. [23] In the U.S., Delaware is the only East Coast state without oyster aquaculture, but making aquaculture a state-controlled industry of leasing water by the acre for commercial harvesting of shellfish is being considered. Recreational oyster harvesting is strictly prohibited to protect both the threatened oysters and to protect people from potential disease. [24] Bycatch reduction devices are required and violation results in a small fine. [25] Supporters of Delaware's legislation to allow aquaculture cite: revenue, job creation, and nutrient cycling as the benefits. For example, It is estimated that one acre can produce nearly 750,000 oysters, which could filter between 15 and 40 million gallons of water daily. [24] This is extremely beneficial to the marine ecosystem because the oysters feed on particulate matter and nitrogen, often from anthropogenic sources. This, in turn, reduces the algae growth and leads to an overall cleaner marine environment. [26] [27]
Other sources state that a single oyster can filter 24–96 liters a day (1–4 liters per hour). [28] With 750,000 oysters in one acre, 18,000,000-72,000,000 liters of water can be filtered, removing most forms of particulate matter suspended in the water column. The particulate matter oysters remove are sand, clay, silt, detritus, and phytoplankton. [28] These particulates all could possibly contain harmful contamination that originates from anthropogenic sources (the land or directly flowing into the body of water). [29] Instead of becoming ingested by other filter feeders that are then digested by bigger organisms, oysters can sequester these possibly harmful pollutants, and excrete them into the sediment at the bottom of waterways. [28] To remove these contaminants from the sediment, species of seaweed can also be added to the aquaculture to take up some of these contaminants in their plant tissues. The seaweed can then be removed and taken to a contained area where the contamination is benign to the surrounding environment. [30] More recently, large-scale cultivation of oysters and other shellfish has been proposed as a method to combat climate change, because the growth of the oyster shell sequesters atmospheric carbon dioxide in a form (calcium carbonate) that is stable over geologic time. [31] [32] [33] [34] In The United States, the cultivation of Pacific oysters in tidal areas not only improves water quality in the ocean but oyster cultivation also works to improve government policy.
Oyster farming must obey federal regulations, maps, and models. Federal regulation monitors the safety of the environment and the health effects on humans. [35] For example, Carlsbad Aquafarm located in Southern California is cultivating Pacific oysters by using rafts and trays to utilize space to optimize production while operating near the newly opened Claude Lewis Carlsbad Desalination Plant. [36] New adopted environmental impact regulations and policies were created and updated by The United States Environmental Protection Agency, which approved the location and construction of the Claude Lewis Carlsbad Desalination Plant through the federal Clean Water Act on April 7, 2016, whose main focus was minimizing environmental impact in conjunction with Carlsbad Aquafarm. [37] Applications and permits for aquaculture projects such as the Avalon Ocean Farm are made public and required to follow the same guidelines of the EPA and the CWA. Water Quality, Marine Mammals (including endangered species), and forecasted environmental impact evaluations are listed in the project's description to minimize, manage, and mitigate its environmental impact.
Oyster predators include starfish, oyster drill snails, stingrays, Florida stone crabs, birds, such as oystercatchers and gulls, and humans.
Pathogens that can affect either farmed C. virginica or C. gigas oysters include Perkinsus marinus (Dermo) and Haplosporidium nelsoni (MSX). However, C. virginica are much more susceptible to Dermo or MSX infections than are the C. gigas species of oyster. [38] Pathogens of O. edulis oysters include Marteilia refringens and Bonamia ostreae . [39]
Dermo disease is caused by a protozoan parasite that infects the oyster's blood cells: Perkinsus marinus. It is spread when infective stages are released into the water column from an infected oyster and siphoned into a new host. It is most common in water above 77 °F. [40]
MSX stands for “Multinucleated Sphere Unknown” and is lethal to C. virginica. It is a single-celled protozoan with an unknown method of transmission between oysters. It does not appear to transfer from oyster-to-oyster like Dermo does. After an outbreak in 1997, a strain of MSX-resistant oysters were developed. MSX can be suppressed by low temperatures and low salinities, but once infected, oysters will die within a month. [41]
MSX and Dermo are both considered to be non-harmful to humans. Vibrio, however, is a disease that is carried by oysters and other shellfish and can make people sick, but is not harmful to the oyster itself. Vibrio can only be passed from oysters to humans if they are consumed raw. Vibrio is more common in warmer waters, and all commercial shellfish must be refrigerated before being served in an attempt to kill the vibrio bacterium. [42]
Polydorid polychaetes are known as pests of cultured oysters. [43]
In the north Atlantic Ocean, oyster crabs may live in an endosymbiotic commensal relationship within a host oyster. Since oyster crabs are considered a food delicacy they may not be removed from young farmed oysters, as they can themselves be harvested for sale.[ citation needed ]
Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some are found in freshwater. In addition, a few species of land crabs are eaten, for example Cardisoma guanhumi in the Caribbean. Shellfish are among the most common food allergens.
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all oysters, are in the superfamily Ostreoidea.
The eastern oyster —also called the Atlantic oyster, American oyster, or East Coast oyster—is a species of true oyster native to eastern North and South America. Other names in local or culinary use include the Wellfleet oyster, Virginia oyster, Malpeque oyster, Blue Pointoyster, Chesapeake Bay oyster, and Apalachicola oyster. C. virginica ranges from northern New Brunswick south through parts of the West Indies to Venezuela. It is farmed in all of the Maritime provinces of Canada and all Eastern Seaboard and Gulf states of the United States, as well as Puget Sound, Washington, where it is known as the Totten Inlet Virginica. It was introduced to the Hawaiian Islands in the 19th century and is common in Pearl Harbor.
Perkinsus marinus is a species of alveolate belonging to the phylum Perkinsozoa. It is similar to a dinoflagellate. It is known as a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as dermo or perkinsosis, and is characterized by the degradation of oyster tissues. The genome of this species has been sequenced.
A fish hatchery is a place for artificial breeding, hatching, and rearing through the early life stages of animals—finfish and shellfish in particular. Hatcheries produce larval and juvenile fish, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops.
The Pacific oyster, Japanese oyster, or Miyagi oyster is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.
Ostrea edulis, commonly known as the European flat oyster, is a species of oyster native to Europe. In Great Britain and Ireland, regional names include Colchester native oyster, mud oyster, or edible oyster. In France, Ostrea edulis are known as huîtres plates except for those that come from the Belon River estuary in Brittany, France, which are known as Belons.
Integrated multi-trophic aquaculture (IMTA) is a type of aquaculture where the byproducts, including waste, from one aquatic species are used as inputs for another. Farmers combine fed aquaculture with inorganic extractive and organic extractive aquaculture to create balanced systems for environment remediation (biomitigation), economic stability and social acceptability.
Netarts Bay is an estuarine bay on the northern Oregon Coast of the U.S. state of Oregon, located about 5 miles (8.0 km) southwest of Tillamook. The unincorporated community of Netarts is located on the north end of the bay and Netarts Bay Shellfish Preserve, managed by Oregon Department of Fish and Wildlife, is located on the south side of the bay. The sand spit on the west side of Netarts bay is part of Cape Lookout State Park.
Ostrea lurida, common name the Olympia oyster, after Olympia, Washington in the Puget Sound area, is a species of small, edible oyster, a marine bivalve mollusk in the family Ostreidae. This species occurs on the northern Pacific coast of North America. Over the years the role of this edible species of oyster has been partly displaced by the cultivation of non-native edible oyster species.
Aquaculture started to take off in New Zealand in the 1980s. It is dominated by mussels, oysters and salmon. In 2007, aquaculture generated about NZ$360 million in sales on an area of 7,700 hectares. $240 million was earned in exports.
Haplosporidium nelsoni is a pathogen of oysters that originally caused oyster populations to experience high mortality rates in the 1950s, and still is quite prevalent today. The disease caused by H. nelsoni is also known as MSX. MSX is thought to have been introduced by experimental transfers of the Pacific oyster, which is resistant to this disease.
Haplosporidium is a genus in the order Haplosporida.
Scallop aquaculture is the commercial activity of cultivating (farming) scallops until they reach a marketable size and can be sold as a consumer product. Wild juvenile scallops, or spat, were collected for growing in Japan as early as 1934. The first attempts to fully cultivate scallops in farm environments were not recorded until the 1950s and 1960s. Traditionally, fishing for wild scallops has been the preferred practice, since farming can be expensive. However worldwide declines in wild scallop populations have resulted in the growth of aquaculture. Globally the scallop aquaculture industry is now well established, with a reported annual production totalling over 1,200,000 metric tonnes from about 12 species. China and Japan account for about 90% of the reported production.
Oyster reef restoration refers to the reparation and reconstruction of degraded oyster reefs. Environmental changes, modern fishing practices, over harvesting, water pollution, and other factors, have resulted in damage, disease, and ultimately, a large decline in global population and prevalence of oyster habitats. Aside from ecological importance, oyster farming is an important industry in many regions around the world. Both natural and artificial materials have been used in efforts to increase population and regenerate reefs.
South Korea is a major center of aquaculture production, and the world's third largest producer of farmed algae as of 2020.
The Suminoe oyster, is a species of true oyster which inhabits intertidal hard grounds and substrate, as well as muddy creeks of warm estuaries throughout the western Pacific. It is large and flat in appearance and almost identical in gross morphology to Crassostrea virginica.
The term oyster reef refers to dense aggregations of oysters that form large colonial communities. Because oyster larvae need to settle on hard substrates, new oyster reefs may form on stone or other hard marine debris. Eventually the oyster reef will propagate by spat settling on the shells of older or nonliving oysters. The dense aggregations of oysters are often referred to as an oyster reef, oyster bed, oyster bank, oyster bottom, or oyster bar interchangeably. These terms are not well defined and often regionally restricted.
Vibrio tubiashii is a Gram-negative, rod-shaped (0.5 um-1.5 um) marine bacterium that uses a single polar flagellum for motility. It has been implicated in several diseases of marine organisms.
The Oyster Recovery Partnership (ORP) is a 501(c)(3) nonprofit organization that leads conservation efforts of the native Eastern oyster, Crassostrea virginica, in the Chesapeake Bay and Eastern United States. The organization's activities and programs include oyster restoration, shell recycling conservation, and sustainable fishery initiatives.