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Washing clams readying them for market in a clam aquaculture facility.

These definitions were developed from submissions by members of the Seafood Industry. Please contact us with additional definitions or corrections that we may add to this seafood processor definitions list. Add new seafood processor definitions.

Oysters & Shellfish Terms and Definitions

Additional Terms & Deifinitions


  • Abalone — a mollusk, related to a sea snail, similar in flavor to a clam. It may be cooked by various methods and is best suited to very long or very short cooking times. Also called "awabi" in Japanese cuisine and "loco" in South American cuisine.

  • Adductor Muscle — A prominent organ situated in the posterior region of the oyster body, consisting of an anterior translucent part and a smaller, white crescent-shaped region. It functions to close the oyster shells (relaxation of the adductor muscle allows the shells to gape open).

  • Affinage — "Affinage" means "refinement" and describes an additional step in the French cultivation process. Usually oysters of marketable size are collected and placed into a special feeding environment. This could possibly be a refinement compound (called a "claire") or a certain river estuary. The duration of 'affinage" can vary from weeks to months. Most areas in France have strict rules associated with 'affinage". See also report "Affinage"

  • Ambulance (d'Huitres) — A shallow rectangular cultivation cabinet, usually made of wood. A matching wood frame with meshing of some sort serves as a lid. The box is placed into the shallow tidal zone and serves as a nursery for baby oysters which have been damaged during their removal from collection tiles. The meshing allows nutritious water in and keeps predators out. Historically, the use of this type of cultivation box is associated with the Arcachon Bay.

  • Anus — The opening of the rectum into the cloacal chamber.

  • Au grand air — Conditioning of the abductor muscles of oysters in special basins before shipment. In the course of about 10 days, the water level is lowered and raised artificially to teach the oysters to forget the rhythm of their natural tidal environment. Once they get used to being exposed to the 'fresh air" (or "grand air"), they will stay shut longer during transport and retain their freshness better. Also known as "trompage".


  • Banding — A strong elastic is placed around the claws of live lobster for safe handling and to preserve quality.

  • Baskets — Vessel in which the oysters are grown. The basket mesh comes in a variety of sizes (4mm - 20mm) to suit the size of the oysters within.

  • Belon (Bélon) — It designates European oysters which have been refined in the estuary of the Belon River in southern Brittany.

  • Berried Lobster — A female with eggs under her tail. Under Canadian law, these must be returned to the water.

  • Batch — A specific group of oysters that were put into the water at the same time.

  • Bivalve — Marine or freshwater mollusk that has two shells.

  • Bourriche — A special basket with a lid, often made of thin wood slats or wicker, for shipping oysters. The size varies. Depending on size, some can hold 100 - 144 oysters. A mandatory certificate indicating origin, quantity, size, and weight is attached.

  • Brine — Salt water used to cushion and insulate a whole cooked lobster in a cello sleeve (a "popsicle pack").


  • Calibres — French weights and measures system for oysters. Pacific oysters and European oysters are rated differently:

    Pacific oysters (Crassostrea gigas)

    Nummer 5 4 3 2 1 0
    Abb. P M M G TG TG
    Weight 30-45g 46-65g 66-85g 86-110g 111-150g 150g+

    Abbreviation key:
    "P": Petit (small)
    "M": Moyen (medium)
    "G": Grand (large)
    "TG": Très Grand (very large)

    European oysters (Ostrea edulis)
    Nummer 4 3 2 1 0 00
    Abb. P M M M G TG






    Particularly large European oysters: "000" = 110g, "0000" =120g, "00000" = 150g ... and more.

  • Canners — A small lobster, weighing approximately 170 to 454 grams (.5 lb. to 1 lb.)

  • Carapace — Body shell, measured from the back of the eye socket to the end of the shell to determine legal size.

  • Cavaliers — Younger oysters which grow on the flat (right) valve of marketable oysters. As they often can't be removed without destroying one or the other oyster. French growers find them undesirable. American growers sometimes call these oysters "jockeys".

  • Captage — Captage describes the deliberate effort of oystermen to capture oyster babies on special collectors. Tile, PVC-pipe, wooden posts, oyster shells etc. can be used. Arcachon and Marennes-Oléron are of great commercial importance in this endeavor.

  • Chai à trier — A typical French work building for oyster growers. At times it may double as living quarters as well. The Marennes-Oléron area is particularly famous for this type of building. Rows of work buildings, each building painted in a different color, creates a beautiful sight.

  • Chaulage — Chaulage describes a special process of coating ridge tiles with a quicklime mixture. The tiles are used to capture oyster babies. See also report on "Captage".

  • Cherry Stone — Approximately 6-10 cherry stone clams per pound.

  • Chixs (chickens) — Lobster weighing approximately 454-500 grams (1 to 1-1/8 lb.)

  • Claires — A generic term describing large water basins used in the cultivation process of oysters. Claires can have a number of important functions. Marennes-Oléron is particularly famous for its claires. See also the report on "Claires" as well as "Affinage".

  • Cold canning — Lobster meat vacu-packed in metal container and frozen, but non-hermetically sterilized. This product must be kept frozen.

  • Cold pack — Frozen lobster meat, packed in cans, not retorted. Frozen storage is required.

  • Collecteurs — Materials used specifically for the capture of oyster babies. The most famous "collecteurs" are coated ridge tiles. See "captage" and report on "captage"

  • Cloacal Chamber — A chamber which passes excess water and waste from the oyster into the environment. In addition, it houses the adductor muscle and rectum.

  • Commensal Organisms — Organisms that rely on a host for a benefit but does not harm or benefit the host (i.e., an oyster bar provides protection for crabs and a hard substrate for barnacle settlement).

  • Concession — A surveyed oyster bed leased from the respective province or French government.

  • Conchyliculture — The term describes anything and everything associated with the cultivation of shellfish.

  • Coral — Internal roe or eggs.

  • Coursières — Canals of varying size which aid in the filling and draining of cultivation compounds.

  • Couteau à huitre — Oyster knife

    Creuse — Colloquial term for the Pacific oyster (Crassostrea gigas). Another colloquial name for the Pacific oyster is "Japonaise". Since about the mid 1970s, the Pacific oyster is by far (more than 90%) the principal oyster cultivated and sold in France (or Europe for that matter). For abot 100 years before that time, the Portuguese oyster (Crassostrea angulata) was the principal oyster grown and traded. During that century, it was also called a "creuse" (or "Portugaise"). Between the years 1968 and 1972, an oyster disease devastated the Portuguese oyster in European waters.

  • Crible — A mechanical sieve or strainer which helps sort different oyster baby sizes.

  • Crusher or Crushing claw — The larger of the two claws.

  • Cull — A lobster with one or no claws, normally sold at a lower price.

  • Cutting claw — The smaller of the two claws.

  • Culture des huitres — Oyster cultivation.
    The three main cultivation methods used in France are:
    * Ground cultivation: "Culture au sol" in the inter-tidal or sub-tidal zone. "En eau profonde" usually describes cultivation in deeper water in the sub-tidal zone with boats and dredges.
    * "Rack and bag": "Surélevé" ("raised higher").
    Oysters in special synthetic mesh bags (called "poches") are grown out on steel racks in the tidal zone.
    * Suspended cultivation: "Suspendu" or "Elevage sur cordes".
    Describes a number of techniques such as synthetic mesh cages hanging from rafts or floats (European oyster). "Elevage sur cordes" describes what we call "longline cultivation". While in American cultivation the "longlines" with oysters are usually stretched out across a series of posts horizontally, they hang vertically in the French region "Bassin de Thau" from wooden racks. See also "Mediterranean".


  • Deuces — Lobsters weighing 900-1135 grams (2 to 2.5 lb.)

  • Dédoublement — "Dedoublement" is an important (and tedious) step in the "rack and bag" cultivation process, whereby the contents of a mesh bag full of oysters ("poche') are removed and redistributed into two or three new mesh bags (or "poches"). Over time, all the oysters in a "poche" naturally grow out and this mesh bag gets increasingly cramped for space. This encourages shell deformities and also compromises the oysters' ability to feed. "Dédoublement" or "parting out" the "poche" simply gives the oysters the necessary "elbow room" to live and grow out favorably.

  • Dégorgeoir — The term "dégorgeoir" or "bassin dégorgeoir" usually describes a shallow rectangular basin made of concrete. It accomodates many steel or plastic baskets with oysters, which are filtering clear water to expell any kind of impurities (sand, mud...) and will soon be shipped. These basins are another form of "claire".

  • Depuration Processor (DP) — Processor who receives shellstock from approved, conditionally approved, restricted, or conditionally restricted growing areas and submits such shellstock to an approved depuration process.

  • Détroquage — "Détroquage" describes separating oyster babies from a substrate such as coated tiles. The traditional hand method requires much skill. Mechanical equipment is also used for détroquage. See also report on "Captage".

  • Diploid — Oysters which have two pairs of matching chromosomes, and that spawn naturally in warm water.


  • Eggs — Haploid gametes produced by females.

  • End Caps — Baskets with triangular shaped end caps.

  • Epibranchial Chambers — A chamber that is formed by the fusion of the mantle and visceral mass and the base of the gills and houses the gills, mouth and labial palps.

  • Esophagus — Tube that connects the mouth with the stomach.



  • Gills — The gills are the largest organ in the oysters body and consists of four folds of tissue. Along with the mantle it is the chief organ of respiration. They create water currents, collect food particles, and move food particles to the labial palps for further sorting. Also serve to separate masses of eggs released from the ovary during spawning into individual ova for efficient fertilization.

  • Girdling — Enclircling the live lobster's claws with a flexible band to ensure safe handling and quality.

  • Grading — Means by which different sized oysters are separated and then placed into baskets with similar sized oysters.

  • Gravette — Traditional name for European oysters (Ostrea edulis) from the Arcachon Bay. Alternative colloquial name for European oysters is "Plates".


  • Halves — Lobster weighing 680 to 800 grams (1.5 to 1.75 lb.)

  • Hard Shell — A lobster whose shell has fully hardened after molting. Hard-shelled lobsters yield 50% to 60% more meat than soft-shell lobsters ("shedders").

  • HCP — Heat-cool pasteurization of oysters. Process involves submerging the raw product into warm water followed by immediate cold water immersion. Shellstock is washed, graded, sorted, banded and treated. Banded oysters are placed on a large tray and then a hoist lifts and places them in warm water at 127oF for 24 minutes. The trays are lifted out and placed in 40oF water for 15 minutes. The trays of cooled, banded oysters are stacked on carts to drip dry ready for boxing and storage.

  • Heat canning — Hermetically sterilized canned lobster for long storage.

  • Hemolymph — Circulatory fluid found in all mollusks and many other invertebrates.

  • HHP — High pressurization processing. Processing starts with cleaning, washing, sorting and grading oysters. They are then banded and containerized (placed in a stainless steel cylinder) in preparation for the high-hydrostatic pressure of 45,000 pounds per square inch. After pressurization, the oysters are then shucked for half shell or packaged as banded oysters.

  • Hinge — The area formed by the joined valves at the anterior of the oyster.

  • Hot Pack — Canned lobster, retorted and shelf stable.

  • Huîtres — The area formed by the joined valves at the anterior of the oyster.Only two kinds are found in French fish markets: the Pacific oyster and the European oyster. They are easily qualified as one or the other. The Pacific oyster tends to be oval with a roughly ribbed shell. One half of the shell looks distincly "hollowed out" or bellied, while the other looks rather flat like a lid. If the sign says "creuse" (which means "hollowed out") it's definitely a Pacific oyster. The European oyster looks rather flat and often (hardly always) somewhat round. The shell looks comparatively smooth. If the sign says "plate" (which means "flat") it's definitely a European oyster. If all else fails, the price tag will often tell the difference, as the European oyster will cost twice (or possibly three times) as much as the Pacific oyster.



  • Jumbos — Whole lobsters weighing more than 1135 grams (2.5 lb.) Jumbos are graded as small (1135-1475 grams or 2.5 to 3.25 lb.), medium (1475-2270 grams or 3.25 to 5lb.) and super (2270 grams + or over 5 lb.)



  • Labial Palps — Consist of two pairs of large, soft flaps that have a roughly triangular shape and have a smooth surface and a rough surface. These specialized organs are known to control the total amount of food ingested, but may also sort food before ingestion, perhaps on the basis of particle size or chemical composition.

  • LFA — Lobster Fishing Area; regions in Atlantic Canada where lobster fishing is open at specific times of the year (seasons). The division into LFAs allows control of the harvest. Minimum size of lobsters varies from area to area.

  • Little Neck — The smallest size of clam amounting to 7-10 clams per pound.

  • Liver — Green-coloured digestive organ of the lobster used to flavour dips and sauces.

  • Lobster tank — Basin used to store live lobster.


  • Mannes — Practical work baskets (often square or rectangular) made of steel or plastic which facilitate moving oysters around for sorting, placement in claires, moving empty shells etc.

  • Mantle — Two fleshy folds of tissue that cover the internal organs of the oyster and are always in contact with the shells but not attached to them. Its principal role is the formation of the shells and the secretion of the ligament as well as playing a part in other biological functions (i.e., sensory reception, egg dispersal, respiration, reserve stores, and excretion).

  • Markets — A size category for lobsters weighing 454 grams and up, usually destined for the live market.

  • Medium — Lobster weighing 570 to 680 grams (1.25 to1.5 pounds).

  • Mollusk — Organisms in the phylum Mollusca - invertebrate animals with soft unsegmented bodies usually enclosed in a calcareous shell.

  • Mouth — The inverted U-shaped slit located between the inner and outer labial palps.


  • Naissain(s) — Oyster baby (babies).

  • Nobashi(Stretched Shrimp) — Increasing the length of peeled and deveined shrimp and minimizing its curling by making parallel cuttings at the bottom, and applying pressure using simple mechanical devises is a new technology adopted by the seafood processing industry in recent years.


  • Ostréiculteur(s) — Oyster farmer(s) or oyster grower(s).


  • Pacific Oyster — Crassostrea gigas, native to Japan and is an introduced species.

  • Paquets — A number of oysters which have grown together as a clump. These clumps are sometimes also called "Pignes" (pine cones).

  • Parqueur(s) d'huitres — Oyster farmer(s) or oyster grower(s). Alternative name for Ostr — iculteur(s).

  • Parqueuse(s) d'huitres
    Female oyster farmer(s) or oyster growers.

  • Pied de cheval — "Pied de cheval" ("horse hoof") describes a particularly large (old) European oyster. Old European oysters can get quite heavy, some weighing 10 oz or more (weights up to 3 lb are known). They are somewhat rare and quite desirable. They are usually harvested by dredging. Approx. 100 -150 metric tons are harvested in France annually (primarily in Brittany and Normandy). France additionally imports approx. 150 metric tons of these monsters from Spain and Great Britain annually.

  • Pignot — A wood post serving as a boundry marker on an oyster bed.

  • Pinasse — A "pinasse" describes a small sail boat design which served French oystermen for centuries as an important work boat. They were about 20 to 30 feet long, narrow, flat bottomed, with a round stern, usually equipped with one mast (occasionally also two), no jib, a center board at times and a rudder, with plenty carrying capacity for oysters. If the oystermen happened to get stuck in a prolonged wind lull, they could return to shore by paddle. Pinasses are now valuable collectibles and are often lovingly restored and cared for by their owners. These beautiful little crafts, although once used by ostermen in varios regions of France, were particularly common in the Arcachon Bay. Incidentally, Connecticut was the birth place of a strikingly similar oyster sail boat design called "sharpie". It was ideally suited for tonging. A Mr. James Goodsell invented sharpies in 1848.

  • Pincher claw — The smaller claw.

  • Plate — Colloquially refers to a European oyster (Ostrea edulis). The "huÎtre plate" was once the mainstay of the French oyster industry. Centuries of over-harvesting reduced its numbers drastically by the 1850s, resulting in spectacular French oyster cultivation efforts led by the famous naturalist Coste (see also report on "Coste"). In the 1970s, two oyster diseases (Martellia refringens, Bonamia ostrea) took a terrible toll on the remaining stocks. Today, the European oyster accounts for a mere 1 - 4% of total French oyster production. European oysters are highly desirable. Although they are considerably more expensive than the Pacific oyster, there is never a shortage of buyers.

  • Plate (2) — The term "plate" also describes a common French oyster work boat. Inset image: A typical "plate" with shallow-draft hull and lots of work space on deck. Ideal also for stacking many "poches" (picture of a plate stacked with poches here).

  • Poche — A "poche" is a synthetic mesh grow out bag for oysters. The "poches", filled with oysters, are laid out on low steel racks in the tidal zone. The "rack and bag" cultivation method was invented in France. Word has it that an enterprising oysterman in Normandy utilized abandoned field bed frames after WW II as racks in the tidal zone and placed bags of oysters on them for grow out. "Rack and bag" is the dominant cultivation method in France. It is also practiced on a large scale by oyster growers on the U.S. and Canadian West Coast (on a limited scale on the East Coast as well). Although the basic concept of the "rack and bag" method is simple, the proper execution of this cultivation method is labor intensive and requires quite a bit of know-how. It will be discussed in detail in the cultivation section of at a later date.

  • Popsicle pack — Term used to describe a whole cooked lobster, packed in brine in a cello sleeve and frozen.

  • Portugaise — Colloquial name for the Portuguese oyster. Also see "Creuse" above.

  • Post Harvest Processor (PHP) — Certified dealer with the capability to apply a validated post harvest process to reduce the level(s) of hazards not addressed by controls in the 2003 NSSP Guide for the Control of Molluscan Shellfish Chapters XI through XIV.

  • Pound — A storage area for holding live lobsters.

  • Pseudopodia — "False feet" that extend from the hemocyte that enable mobility and capture of foreign bodies and other materials.


  • Quahog — These clams are also called chowder clams and weigh in at a 2-3 clams per pound.

  • Quarters — Lobster weighing 570 to 680 grams (1.25 to 1.5 lb.)


  • Rectum — Organ that is the continuation of the intestine; it runs dorsally over the adductor muscle and ends in the anus, and aborts water while consolidating feces.

  • Repacker (RP) — Person other than the original certified shucker-packer who repacks shucked shellfish into other containers. A repacker also may repack and ship shellstock. A repacker shall not shuck shellfish.

  • Reshipper (RS) — Person who purchases shucked shellfish or shellstock from other certified shippers and sells the product without repacking or relabeling to other certified shippers, wholesalers, or retailers.


  • Sauvage — A "sauvage" (a "wild one" or "savage") designates a very large Pacific oyster. Unlike its counterpart among the European oysters, the "Pied de Cheval" (see above), a "sauvage" is quite common and inexpensive along the coast of France. Although they are too big for slurping off the half shell, they are nonetheless tasty and tender oysters, ideally suited for many recipes.

  • Seasons — Specific periods in the year when a particular area or region can be fished.

  • Selects — Lobster weighing 800 to 900 grams (1.75 to 2.0 lbs.)

  • SET — Short for a settlement of clam larvae, as they descend from the surface to the clam bed.

  • Seapa — Baskets with an oval shaped end cap.

  • Shedders — Lobster in the molt or soft-shell stage of growth.

  • Shellfish — All edible species of oysters, clams, mussels, and scallops, either shucked or in the shell, fresh or frozen, whole or in part.

  • Shellstock Shipper (SS) — Person who grows, harvests, buys, or repacks and sells shellstock. They are not authorized to shuck shellfish nor to repack shucked shellfish. A shellstock shipper may also ship shucked shellfish.

  • Shucker-Packer (SP) — Person who shucks and packs shellfish. A shucker-packer may act as a shellstock shipper or reshipper or may repack shellfish originating from other certified dealers.

  • Shucking — Opening an oyster.

  • Small — Lobster weighing 454 to 500 grams (1 to 1 1/8 pounds).

  • Soft Shell — A lobster after it molts or sheds its hard shell to facilitate growth. During this soft-shell period, meat yield is low, and meat texture and flavor are poor.

  • Spat/Seed — The oyster at its larval stage.

  • Stomach — A large sac-like organ that is divided into two chambers used in the digestion and sorting of food particles.

  • Stretched Shrimp(Nobashi) — Increasing the length of peeled and deveined shrimp and minimizing its curling by making parallel cuttings at the bottom, and applying pressure using simple mechanical devises is a new technology adopted by the seafood processing industry in recent years..


  • Table à caire-voie (Tables à claire-voie surélevées) — "Table a caire-voie" are the low steel racks upon which mesh bags of oysters (or so called "poches") are placed fro grow out in the tidal zone. Basic concrete reinforcing bar (rebar) properly welded together works well and is commonly used. The bags usually end up sitting on these racks about 20' to 24" (approx. 50 - 60 cm) above the ground. The length varies - 9 to 10 feet (approx. 3 m) is common.

  • Table lobster — Lobster weighing 454 grams or more, generally sold live.

  • Tentacles — Small sensory organs attached to the edge of the mantle used for the detection of environmental stimuli.

  • Tomalley — Green-colored edible liver, used to flavor spreads and sauces.

  • Top Neck — These clams are also labeled as count neck clams and equal roughly 4 clams per pound.

  • Trap — A cage-like structure used to catch lobsters alive.

  • Trays — Wood framed, mesh enclosed trays in which the spat is grown until they are large enough for baskets.

  • Triploid — Functionally sterile oysters that do not spawn. Allows them to keep their condition for longer than normal (diploid) oysters. They also grow faster than diploids because the energy that normal oysters put into reproduction can instead be used for growth. Triploid oysters have 3 sets of chromosomes.

  • Trompage — See "Au grand air" above.


  • Umbo — The anterior end of the oyster. It is pointed and the oldest part of the oyster.


  • Valves — The two shells of the oyster.


  • Watermen — Individuals who earns an income from harvesting aquatic resources.




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