Any mollusk that has two shells hinged together by a strong muscle, such as a clam, oyster, cockle, or mussel. They are important around the world and in many diverse cuisines. Some can be eaten raw, most must be cooked.

Blast Freezing
Freezing by circulating cold air over batched product placed in trays or racks. Continuous operations are available with rotating belts or spiral screens.

Method in which fishermen remove blood from fish by cutting  an artery. Large meaty fish like tuna are routinely bled before further processing. Skates and sharks are also bled to remove uric acid.

Term used by packer to indicate that product has been processed to remove backbone and rib bones.

Brine Freezing
Freezing seafood by soaking in liquid brine. King crab or snow crab is often brine-frozen.

Butterfly Fillet
Fish is cut along both sides with the two pieces remaining joined by the skin of the back. Technically, two pieces held together with the belly skin is called a kited fillet.

Butterfly Shrimp
Peeled and deveined shrimp with the shell left on the last (tail) segment. Shrimp in this form is often breaded.

This is the fish and other marine life that are incidentally caught with the targeted species in a fishery. Bycatch is typically discarded dead at sea, and includes seabirds, marine mammals, turtles, juveniles of the targeted species, and even fish sought after in other fisheries. It is estimated that one-quarter of the global fishery catch is discarded each year as bycatch.
Cooked and peeled shrimp. Can be deveined as well.

A mixture of flour or meal; one or more seafood components and other ingredients such as vegetables and seasonings in a batter that is sautéed, fried or baked.

A process by which fillets are placed on a backlighted, translucent table that reveals the presence of parasites in the flesh.

Cello Wraps
Fillets wrapped together in cellophane or polyethylene film. Each wrap is usually labeled with the type of fish, the packer and the brand. Six polywraps per 5-lb. box is standard.

Center Cut
The center third of a fillet.

Chill Packed
A packing method in which fish are packed in cartons with gel packs and no ice.

A product form consisting of a group of legs and a claw from one side of a crab, with the connecting shoulder area still attached. Also known as a "section."

Cold Smoked
Fish smoked at low temperatures (around 80◦ F) for 18 hours to several days, producing a moist, delicately flavored product.

The bones of a fish just behind the gills; they support the pectoral fins. The collar is waste when a fish is steaked or filleted. Most headless fish are sold with the collar on because it protects the fish.

Cooking Times
Fish is naturally tender, requiring short cooking times at high temperatures. Allow 10 minutes per inch of thickness (at the thickest part) for fresh fish, 20 minutes per inch for frozen fish.

Crustaceans are the aquatic analogs of insects, both being members of the phylum Arthropoda. Found in both fresh and salt water, crustaceans are invertebrates and characteristically have a segmented body and exoskeleton, with limbs that are paired and jointed. Lobsters, crabs, shrimp and barnacles are examples of crustaceans.

Extremely cold freezing process, using liquid nitrogen or carbon dioxide, often used to freeze high-value items like shrimp or soft-shell crabs.

Using salt or sugar to draw moisture from the flesh of fish or other meats to make it unattractive to the growth of spoilage bacteria. Curing was widely used as a preservation method before the advent of modern refrigeration techniques. Today, curing is used to give a pleasing flavor to fish and refrigeration is recommended to preserve this product from spoilage.

Deep Skinned
Removing the fat layer underneath the skin on oily species for milder flavor and improved shelf life.

To remove the sand vein (intestine) from the tail section of a shrimp, lobster or other crustacean.

A number of similar chemicals are used in processing seafoods to help retain moisture, and sometimes to improve the appearance by whitening. The use of dips is long established and so far as is known, harmless. It is common in other parts of the food industry.

Dorsal Fin
The top fin of a fish.

Double Fillet
Fillets cut from both sides of the fish, with the two pieces remaining joined at the back. Also called "butterfly fillet."

Double Frozen
Fish or shellfish that is frozen at sea, thawed for reprocessing in a plant onshore and then frozen a second time. Also called "twice-frozen" or "refrozen."

Drawn Fish
Entrails, gills and scales removed. Since entrails cause rapid spoilage, drawn fish have a longer storage life.

The fishing vessel tows a rigid steel framed dredge along the seafloor to gather scallops or, in the case of oyster capture, a steel ring mesh dredge is used.

Indicates that seafood has been dehydrated by natural (air, sun) or mechanical means.

Drip Loss
Weight loss that occurs as a seafood product gives up moisture. Also, loss of moisture during the thawing of frozen seafood.

Dressed Fish
Completely cleaned but with head on (head removed is usually called pan-dressed). Both forms are ready for stuffing and are generally cooked in one piece.

Drift Net
A large gill net ranging in length up to 40 miles, a drift net is suspended vertically with floats and allowed to range freely in the open ocean. The United Nations has banned the use of drift nets in international waters because of their non-selective catch characteristics. Drift nets in U.S. waters are limited to 1.5 miles in length. See gill net below.

Dry Pack
A pack form of chopped clams that contains no clam juice.

Dry Salting
A coating process used in curing seafood. It helps dry the outside of the product, allowing it to acquire a denser, firmer texture.

Farm raised
Seafood which has been grown in containment and fed a controlled diet.

Frozen at sea.

French spelling for fillet (see Fillet)

A slice of fish flesh of irregular size and shape which is removed from the carcass by a cut made parallel to the backbone, usually 2 to 12 oz. Some fillets, especially of fresh fish and those used to make up the larger frozen blocks, may be larger than 12 oz. However, for most institutional foodservice and home uses, frozen fish fillets over 12 oz. are not generally available. Special cut fillets are taken from solid large blocks; these include a "natural" cut fillet, wedge, rhombus, or tail shape. Fillets may be skinless or have skin on; pinbones may or may not be removed.

The practice of cutting off the fins of sharks and discarding the carcasses overboard. Asia is the primary market for shark fins, which are used to make shark fin soup. Congress banned shark-finning in all U.S. waters in 2000.

The primary protein source for farmed carnivorous fish, fishmeal is made by cooking, pressing, drying, and grinding fish or shellfish. (NMFS)

Fish that have a flat body with both eyes located on the upper side. Flatfish swim "sideways" and include "flounder," "halibut," and "sole." Most of these fish have sweet, delicate white flesh that chefs and consumers everywhere enjoy: low fat, fine textured meat and mild flavor. All flatfish belong to the order Pleuronectiformes, which means they have both of their eyes on the same side of their head. All flatfish start out life looking like normal fish, but after a few weeks, one eye migrates to the other side of their head, their bodies flatten into an oval shape, one side turns dark and one side white and they settle to the bottom.

Large boneless fillet of halibut, swordfish or tuna.

Means free on board and a location usually follows this term. Charges beyond the termination point are the buyer's responsibility.

Freezer Burn
Dehydration caused by the evaporation loss of moisture from product. It is recognized by a whitish, cottony appearance of the flesh, especially at the cut edges or thinner places.

Fresh Frozen
Indicates fish were quickly frozen while still fresh.

Gill Net
A gill net’s mesh size allows the heads of fish to pass through the openings but the gills get caught. Many states, including Texas, Louisiana, Florida and California, have banned the use of gillnets in their coastal waters. Like drift nets, gill nets are associated with some bycatch because they are non-selective. In some cases, however, regulations establish where nets can be placed in the water or what time of day they can be set to help reduce the chances of catching non-targeted species.

Protective coating of ice on frozen product to prevent dehydration. There are laws against excessive glazing.

A term for incremental measurement of seafood products, such as counts per pound of shrimp or weight range of fillets.

Fish that live on or near the seabed, such as cod, flounder, and rockfish. This term is not so much a scientific grouping as a management term. Demersal is the scientific term that describes the fish and other organisms that live near the ocean bottom.

Headed and Gutted (H&G)
Have head and viscera removed before sale.

Analogous to the rod and reel used by recreational anglers, the hook-and-line method attracts fish by a natural or artificial bait (lures) placed on a hook fixed to the end of a line, or snood, on which fish are caught. Hook-and-line units may be used singly or in large numbers.

Individual polywrapped.

Individually quick frozen. Fillets are packed IQF in 2 or 4 oz. gradations; 2-4, 4-6, 8-10, etc. Typical species packed in this manner are whitefish, sole, cod, and Pacific rockfish. Shrimp are also sold IQF, breaded or not-breaded in various forms.

Trimming a fillet removing both the nape and pinbones, usually the most expensive cut.

A method of fishing using lures on a vertical line that is moved up and down (jigged) by hand or mechanically, jigs are extremely efficient for fishing oceanic squids at night. Jigging dates back hundreds of years in New England and Canada for cod fishing.

Layer Pack
Product, usually fillets, put into a carton in layers with a sheet of polyethylene between each layer of product.

The boneless portion of edible flesh cut lengthwise from either side of the backbone of a large, round-bodied fish.

A longline consists of many short lines, each baited with a hook, suspended vertically from a main line that is dragged horizontally through the water. Longlines can carry thousands of hooks and stretch as long as 40 miles. This method is generally associated with moderate to high bycatch, depending on how many hooks there are and where and when the lines are set. Longlines set for tuna, for instance, also catch swordfish, shark, turtles, and seabirds (the latter are attracted to the baited hooks as they are put in the water).

Cured salmon. The curing method makes use of salt.

See Shellfish.

Napecut Fillets
A wide angular cut from the gillcover to the vent eliminating the rib cage, or by slicing it from the fillet.

Net Weight
Net weight is the weight of the product without packing material or glaze. The problem is to determine the net weight without glaze, since most seafood will drip their own moisture for days.

Ocean Run
Industry term for a pack of random weight and size products.

Usually a square or rectangle, cut from a block of frozen fish. Weights vary from 1-1/2 oz. to about 6 oz. May be plain or breaded, raw or pre-cooked.

Purse Seine
A net that is usually set by two boats and is used to catch open-sea or pelagic fish. The boats encircle a school of fish, then the bottom of the net is drawn together like a purse. As with any net, the size of the mesh determines which species is targeted. The “dolphin-safe” logo resulted from public awareness about the bycatch of dolphins associated with purse seines used in the Pacific tuna fishery.

Red Tide
A reddish-colored carpet of algae that appears below the surface of the sea and is eaten by clams, mussels and oysters. The algae secrete a substance that can be toxic to humans. Fishing grounds are closed when red tide occurs, preventing the harvest of any contaminated shellfish.

Most fish species grow their eggs in a sac in the abdomen, and the roe of some species is considered a delicacy in various countries. Sturgeon roe, or caviar, is the best-known and most expensive in the U.S., but cod, herring, mullet, pollock, salmon and shad all produce roe prized by various regional and ethnic groups.

Refers to physical shape of the body of the fish, and is more a convenient way to group all fish other than those in the flatfish family than a scientific classification. (See Flatfish).

A microorganism causing food poisoning in humans, salmonella is very common and is found on meat, poultry and rarely, seafood. Normal cooking destroys salmonella.

Another name for large shrimp, usually about 1 oz. or larger. Outside the U.S., the term is also applied to lobster. Also a method of preparation, usually with shrimp, that includes butter and garlic.

Also spelled schrod. Small Atlantic cod, haddock or pollock whole, 2.5 pound or less. Available whole dressed or as fillets.

The three walking legs and one claw on one side of king, snow or Dungeness crab, all attached at the shoulder.

A box of frozen fish fillets separated by interleaved polyethylene sheets. Fillets can be separated by dropping the box, "shattering" the pack.

Two major groups of seafood are called shellfish. Mollusks include clams, oysters, mussels, conch, snails and scallops. Crustaceans include shrimp, crabs, lobster and crawfish. Squid and octopus are generally considered shellfish as well.

Some species of fish are skinned rather than dressed, such as catfish and eels.

The term "Sole" does not define a specific species of fish. In fact, it refers to a flat, white, boneless piece of fish known as the "Fillet of the Day." Varieties include but are not limited to Yellow Tail, Grey, and Lemon Sole; these are all actually flounders.

Slices of dressed fish smaller than chunks. They yield an edible portion of about 86% to 92%. They are ready for cooking. Salmon, halibut, swordfish and other large fish are commonly processed and sold as steaks.

T & T
An abbreviation used to represent Tubes & Tentacles, a common way to retail cleaned squid/calamari.

Fish portion which resembles the tail of a fish, boneless, usually breaded or batter-dipped, raw or precooked. Weights vary from 3-1/2 to 6 oz. Sometimes the entire tail, bone-in, is breaded and frozen for sale as a "tail". The term is also applied to shrimp and spiny lobster with reference to their meaty tail sections.

Fishing by means of devices such as cages that trap fish in a confined environment. Traps are often designed and baited to catch a particular species, as in a crab pot, lobster pot, tuna trap, and fyke net. There is little to no bycatch associated with traps.

A trawl is a sock-shaped net with a wide mouth tapering to a small, pointed end (sometimes called the cod end) that is towed behind a vessel at any depth. This method is more indiscriminate than others because the net scoops up everything in the trawl’s path.

Tripolyphosphate (also, Sodium Tripoly, STP)
A sodium-based additive used to control moisture loss. Often applied at sea to fresh-shucked scallops. Seafood with tripoly added is referred to as "wet," "dipped," or "treated."

Whole or Round Fish
Fish sold just as they come from the water. They must be dressed before cooking