Aquaculture Non-Fish Species

Important Aquaculture Non-Fish Species

Revised January, 2020.

Oysters

Shrimp

Most non-fish species are not well suited to “closed” recirculating-type aquaculture production systems and tend to be raised in outdoor ponds or net pens.  Shrimp and some crayfish species are exceptions and in well-planned operations may be efficiently and economically raised in indoor recirculating systems. 

Oysters

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. The Gulf Coast region, principally Louisiana, generally leads the nation in oyster production. The Pacific region, principally the state of Washington, follows closely, and the Chesapeake region, principally Maryland, ranks third.

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. 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 Coast waters, they historically have been largely harvested from wild reefs (Muth et al.).  Following a series of man-made and natural disasters over the past decade, interest in hatchery production and off-bottom oyster culture is increasing in the Gulf region.

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 handpicked. 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.
 
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.

Processors typically sell oysters as fresh raw shucked, processed halfshell 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.

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.).
 
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.

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Shrimp

shrimpAbout 80% of the seafood consumed in the U. S. is imported. Seafood is the second largest U.S. trade-deficit category behind petroleum.  In 2017, the seafood-related deficit was $21.5 billion dollars and increasing.  Shrimp is the most preferred U.S. seafood followed product, consumption is double that of the second-most preferred product, canned tuna (fishwatch.gov).  Commercial shrimp species support an industry worth 50 billion dollars a year (Rudloe & Rudloe), and in 2018 the total commercial production of shrimp was nearly 4.8 million pounds.

Shrimp are usually marketed according to descriptive product or packaging size wording that is based on “count size.”  This often is confusing to consumers, but is a relatively simple system based on the number of shrimp needed to roughly equal one pound in weight.  For example, count sizes of 10 shrimp or less are “Colossal;” 11 to 15 are “Jumbo;” 16 to 20 are “Extra-Large;” 21 to 30 are “Large;” 31 to 35 are “Medium;” 36 to 45 are “Small;” and 100 or more are called “Miniature.”

World shrimp consumption, fueled by increasing demand from ever-increasing Asian population growth and increasing consumer affluence has led to an increasingly competitive marketplace.  This has impacted both wild-caught and aquaculture-produced shrimp, and has led to large-scale overharvest of ocean stocks, as well as the importation of foreign aquaculture-product that could never meet U.S.-production standards; however, demand is unabated.

In recent years, many consumers have become more aware of both the ecological impact and food-safety issues associated with imported shrimp; consumers also are paying much closer attention to country-of-origin labelling.  The U. S. aquaculture industry for shrimp is in its infancy, but with steadily increasing world demand and increasing consumer awareness, U. S. producers could see strong growth markets.

Additionally, aquaculture shrimp can be an extremely feed-efficient organism to produce.  Since shrimp are low on the food chain, with careful oversight they can be commercially produced under controlled conditions.  Shrimp can be reared on feed pellets in tanks, but research on “counter-current” tank systems has shown that shrimp can be can be fed on highly nutritious “bioflok,” biological flocculent.  This protein-rich food source is a highly oxygenated nutrient and bacterial suspension that can be suspended in the water column and propagated within the shrimp tanks.  The bacteria consume and reproduce from nutrients in the water, then as they propagate, the bacteria clump together into increasingly large particulate masses that eventually reach a particle size preferred by feeding shrimp.  These masses become an almost self-replicating food source and the highly nutritional base for commercial shrimp production.  Depending on species and if given the proper substrate and water chemistry, there is considerable potential to develop highly economical, sustainable and ecologically sound feed systems around “bioflok” or similar production systems.

Systems for producing food in safer ways, including the use of the hazard analysis critical control point (HACCP) system are now being adopted widely throughout the world.  The ever-growing global shrimp and prawn farming and processing industries are now beginning to realize the benefits of using HACCP and other food safety measures.  Commercial producers, large and small, who embrace these systems and communicate their quality control, will find their product increasingly welcome in the marketplace.

Shrimp are highly perishable.  If properly raised, harvested, cleaned, and flash frozen, frozen shrimp can be a fine product.  The informed consumer may want to examine the product label for country-of-origin and similar information before any purchase decisions.  The consumer should select firm product with a mild scent.  There may be hints of ammonia or formaldehyde, or many have spotting on the flesh; signs that the shrimp is past its prime or was improperly handled.  Commercially sold shrimp in most retail settings is defrosted, in which case the flesh will appear opaque.  Truly fresh shrimp like those obtained live from a fisherman or local aquaculture operation, have almost translucent flesh.  In the restaurant and grocery worlds, the term "fresh" should not be interpreted as never-frozen.  It is highly unlikely that the average American consumer will be able to obtain fresh shrimp unless they live in a part of the country near a shrimp-boat fleet or one of the few aquaculture operations that are producing and marketing live shrimp.

Informed consumers may be able to locate some local producers using the MarketMaker and other search engines.  Clearly, with ever-increasing world demand and increasing consumer demand for sustainable and environmentally friendly product, there is great opportunity for local producers of high-quality high-value seafood from aquaculture.

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