Glossary of Terms

Below are some of the terms related to fishing, fisheries management, and the marine environment. Some of these terms are referenced in the Smart Choices species pages. For a more complete listing of terms, please see the resources indicated below.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X Y | Z

A

Algal Bloom

An algal bloom is a proliferation of either phytoplankton or seaweed and is a natural phenomenon. However, nutrient pollution has resulted in a substantial increase in algal blooms along many coastal regions over the past two decades. Phytoplankton blooms can produce toxic effects on humans and other organisms, cause physical impairment of fish and shellfish, or result in severe oxygen depletion of bottom habitats. Blooms involving phytoplankton are sometimes called “red tides” though, in reality, they can be of various colors, or not visible at all. Even miniscule doses of some algal toxins, such as domoic acid or saxitoxin, can cause severe illness or death in humans. Most algal species, however, pose no threat to human health.

Anadromous

This describes species of fish that breed in freshwater rivers and streams but spend most of their adult lives in the marine environment. They return to the same river or stream in which they were born to spawn, or reproduce. Salmon, steelhead trout and striped bass are examples of anadromous fish. (NMFS)

Aquaculture

Aquaculture is the farming of aquatic species, such as fish and shellfish, in salt, brackish, or freshwater. Farming implies private ownership and enhancement of production by stocking, feeding, providing protection from predators and other management measures. According to the Food and Agricultural Organization’s latest figures, about one-third of the seafood consumed worldwide is farm-raised.

B

Benthos

The community of marine life inhabiting the sea floor is referred to as the benthos.

Billfish

Billfish are pelagic fish whose upper jaws are prolonged into a spear or sword, such as marlin, sailfish, and swordfish. (Norse)

Biomass

This is the total weight of a number of organisms or population of a species. It is possible for a fish population to have a high biomass and be overfished.

Bycatch

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. Fisheries managers and scientists, often working in collaboration with commercial fishermen, have sucessfully introduced bycatch reduction devices - such as the Nordmøre grate - in many fisheries.

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C

Cast Net

These are nets cast from the shore or from a boat that catch the fish by falling and closing in on them. The use of cast nets is usually restricted to shallow waters.

Catadromous

The opposite of anadromous species, catadromous species spawn in the sea; their young then migrate to fresh or brackish water to grow and mature. The American eel is an example of a catadromous species.

Catch

This is the total number or weight of fish and other marine life, including bycatch, taken by fishers from an area over some period of time, as opposed to landings, which do not reflect the amount of discards. (Roberts et al.)

Commission for the Conservation of Antarctic Living Marine Resources

Established by treaty in 1980, the CCAMLR is unique among fisheries agreements in that the conservation measures adopted by the Commission must include a fishery’s impact on the entire ecosystem, rather than on just the targeted species. This ecosystem approach aims to prevent a decrease in the size of harvested populations to levels that threaten their stable recruitment, and to minimize the risk of changes in the marine ecosystem that are not potentially reversible over two or three decades. The meetings of the Commission are held annually in Hobart, Australia, with representatives of the 23 CCAMLR member states.

Continental Shelf

The continental shelf is a gradually sloping undersea shelf of land that extends beyond shore of the continent. The nature of this geologic “shelf” is home to a great diversity of fish and shellfish species.

Copepods

Copepods are a large group (approximately 6,000 species) of tiny shrimplike crustaceans. They are an important food source for many larger animals, including fish, seabirds, and baleen whales.

Coral Reefs

Coral reefs are built up over hundreds of years by colonies of small animals, called coral polyps, and their skeletons of calcium carbonate. Coral reefs cover less than 1% of the ocean area but are home to one-third of all marine fish species.

Crustacean

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.

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D

Dredge

Used mainly to target shellfish, dredges employ a heavy mesh to suck up everything from the seafloor. The gear is dragged along the bottom, and the shellfish are held in a sort of bag or sieve which allows the water, sand or mud to run out. Boat dredges vary in weight and size, but they are usually fairly heavy and their effect on bottom habitats is a major concern.

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.

E

Effluent

The waste stream flowing from an aquaculture facility. Wastes can include: particulate matter from fecal material and uneaten food; nutrients; and chemicals and drugs such as pesticides, disinfectants, and antibiotics.

Essential Fish Habitat

First defined by Congress in the 1996 Sustainable Fisheries Act, essential fish habitat is the waters and substrate necessary for fish to reproduce, feed, and grow to maturity. The conservation of habitat in general is important in building and maintaining sustainable fisheries.

Estuary

An ecosystem occurring where a river or stream meets ocean waters, such as the Chesapeake Bay and San Francisco Bay. Estuaries are highly productive areas that serve as important nurseries for juveniles of many commercially important fish species. (Norse)

Exclusive Economic Zone (EEZ)

Established in international law by the Law of the Sea treaty, this is the zone within which a coastal nation has exclusive fishing rights. It typically extends out to 200 nautical miles.

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F

Factory Trawler

This is a large stern trawler, typically 150 to 300 feet in length, equipped with onboard facilities for gutting, filleting, freezing and storing fish, and for processing fish oil and fishmeal.

Fecundity

Whereas fertility is a measurement of the actual number of offspring produced, fecundity is the level or rate of egg or offspring production. Fecundity may change with the size and age of a species. (Waller)

Feed Conversion Ratio (FCR)

The ratio of the gain in wet body weight of fish to the amount of dry feed fed to the fish. Currently, farming of carnivorous fish results in a net loss of fish or protein, since these fish require fish oil and fishmeal for feed. Farming herbivorous and omnivorous fish, such as carp, catfish, and tilapia, results in a net gain of fish or protein, since these fish consume a plant-based diet.

Finning

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.

Fishmeal

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

Fishery

A fishery can be defined in many ways though, in general terms, it is the take or removal of a species from the aquatic environment using some type of fishing technology. The emphasis is on the human aspects of fishing and all the activities it involves.

Fishery Management Council

The Fishery Conservation and Management Act of 1976 as amended created the eight regional councils that are responsible for developing Fishery Management Plans (FMPs) in the federal waters of those regions. Each council consists of representatives from each state in the region and up to nineteen members from various stakeholder groups. The eight regions are New England, Mid-Atlantic, South Atlantic, Gulf of Mexico, Caribbean, Pacific, North Pacific and Western Pacific. See also Sustainable Fishery Act. (NRDC)

Flow-through System (Raceway)

A flow-through system, or raceway, is a type of aquaculture system in which water is diverted from nearby streams or pumped from wells into concrete troughs or tanks where fish are held. The water flows through a series of raceways before being discharged, usually with some form of wastewater treatment.

Food Chain

A food chain is the sequence of organisms through which energy and materials are transferred (in the form of food), or the linear progression of feeding levels in which one organism is the food source for the next. (Waller)

Food Web

This is the complex, interlocking series of individual food chains in an ecosystem, i.e., all the predator-prey relationships.

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G

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.

Groundfish

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.

H

Harpoon

Harpooning is a surface fishing method that requires considerable effort to locate and chase individual fish, as opposed to fishing methods that target schools of fish. Harpoons, which target high-value fish, may be hand-held or fired from a gun. Because harpoons are aimed at individual fish, bycatch is not a concern.

High-Grading

This is the practice of discarding at sea all or a portion of a vessel’s legal catch in order to obtain a higher or larger grade of fish that brings higher prices. It may occur in both quota and nonquota fisheries. (Roberts et al.)

Hook-and-Line

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.

Hypoxia

A state of low dissolved oxygen concentration relative to the level required by oxygen-breathing species. Anoxia is the complete absence of oxygen in the water. Those living creatures that cannot flee oxygen-depleted zones may die if levels drop too low. Every spring, a huge hypoxic region, or “dead zone,” covering about 8,000 square miles appears in the northern Gulf of Mexico due, in large part, to nutrient run-off from the use of agricultural fertilizer. (NRDC)

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I

Ichthyology

This is the study of fishes, including their biology, life history, habitat, diversity and classification.

Individual Non-Transferable Quota

A management tool used to allocate Total Allowable Catch to individual fishermen or companies. They do not represent long-term rights because they are not tradable by their holders. The management authority retains the prerogative to withdraw and redistribute them under certain conditions. (FAO)

Individual Transferable Quota (ITQ)

A type of quota (a part of the Total Allowable Catch) allocated to individual fishermen or vessel owners and which can be sold to others. (FAO)

International Commission for the Conservation of Atlantic Tunas (ICCAT)

ICCAT was established in 1966 out of concern for dramatic declines of bluefin and other tunas. The ICCAT scientific committee annually reviews the status of individual Atlantic tunas and billfishes and recommends management measures, such as size limits or quotas, based on these assessments. The entire body then votes to whether to accept these measures. If the recommendations are adopted, the individual member countries are responsible for implementation. ICCAT thus has no enforcement mechanisms.

Invertebrate

Jellyfish, octopus, and sponges are examples of marine invertebrates, or animals without a backbone. In fishery management terms, invertebrate usually refers to shellfish, such as lobsters, shrimp, oysters, and clams, for which there are significant fisheries.

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J

Jig

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.

K

L

Landings

Commercial landings are defined as the quantity of fish and shellfish brought ashore for sale. The term also applies to the amount caught for personal use by recreational fishermen. This measurement does not include the amount of bycatch incidentally caught and discarded dead at sea.

Law of the Sea (UNCLOS)

The 1982 United Nations Convention on the Law of the Sea is the most comprehensive of the ocean treaties; it lays down a regime of law and order in the world’s oceans and seas, establishing rules governing all uses of the oceans and their resources. It also contains a section on environmental protection, obliging all nations “to protect and preserve the marine environment.” This treaty established the concepts of a 200- nautical mile exclusive economic zone and 12-nautical mile territorial sea.

Longline

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).

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M

Mangrove Forest

Mangroves are salt-tolerant trees primarily found in the intertidal zone of estuaries along tropical and subtropical coasts. Like coral reefs and seagrass beds, mangrove forests are highly productive and serve as important nurseries for a wide range of fish and invertebrates. Mangroves protect coastlines from erosion and contribute much in terms of fuel, food, and fibre for many coastal communities.

Maximum Sustainable Yield

The maximum amount of a species that can be taken without diminishing the future take.

Mercury

Although mercury is a naturally occurring element, it is also released into the environment by various human activities including waste incineration, coal burning, and mining. Mercury is an ongoing public health concern due to its highly toxic nature; exposure to high levels can permanently damage the brain and kidneys and the developing fetus. Children are more susceptible than adults to mercury contamination. Fish consumption is one of the most important exposure routes to humans. Mercury bioaccumulates, meaning that top predators, such as sharks and swordfish, have higher levels in their tissues than, for example, fish that feed on plankton. For further information on human health protection, see the EPA’s Consumption Advisories, the FDA’s Consumer Advisory and the National Academy of Sciences report on methylmercury].

Metric Ton

Often the unit of measurement for commercial and recreational landings, a metric ton is equal to 1000 kilograms, 0.984 long tons, 1.1023 short tons, or 2204.6 pounds.

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N

Nautical mile

One nautical mile is the equivalent of 1.15 statute miles.

Netpen System

A type of fish farm that consists of mesh enclosures (or sometimes cages), typically placed in coastal areas. The outside structures may be rigid or semi-rigid. There is no effective barrier between the netpen interior and the ocean, so wastes are emitted directly into the surrounding waters. This system also creates the potential for farmed individuals to escape into the wild and spread disease to wild populations. Carnivorous fish, such as salmon, are commonly farmed using net pens.

Nordmøre Grate

Sometimes referred to as the Nordmøre grid, this bycatch reduction device is used primarily in shrimp trawl fisheries to exclude large animals from the nets. It features an alluminium grid secured to the trawl at 45-60 degrees from the vertical. Large animals are the guided by the grid towards the escape opening in the top while shrimps and other small animals pass through the grid and enter the codend. Studies indicate the use of this technology has led to significant reduction in the take of marine life associated with shrimp trawl fisheries, see for example: Hannah and Jones. "Effectiveness of bycatch reduction devices in the ocean shrimp (Pandalus jordani) trawl fishery." Fisheries Research 85.1-2 (2007): 217-225.

O

Organic (as it applies to seafood)

According to the United States Department of Agriculture (USDA), “organic” is a labeling term that denotes agricultural products that are grown or made under the authority of the Organic Foods Production Act. The principal guidelines for organic production are to use materials and practices that enhance biodiversity and that integrate the parts of the farming system into an ecological whole.

Currently, no aquaculture-specific organic standards exist in the U.S., and there is much confusion about the current state of organic fish farming. According to some fish farmers, until such standards are developed, producers may obtain organic certification and market their products as organic as long as they comply with USDA’s general organic livestock rules. This has been the case for two shrimp farmers in the U.S., and it is expected that more shrimp farmers, as well as some tilapia and catfish farmers, may follow. Others contend, however, that because no specific standards exist, it is impossible to have an organically certified product, especially when not all organic principles are followed. They argue that fish raised on feed that includes nonorganic ingredients such as fishmeal made from wild-caught fish and preserved with synthetic chemicals do not meet the definition of organic. Many producers and consumers are looking to USDA’s National Organic Standards Board to resolve these issues.

Organic aquaculture standards have been developed in several other countries, and, as a result, aquaculture products certified to these standards and labeled as organic have started to show up in U.S. markets. However, one should note that these products do not meet USDA organic standards, which, as stated above, do not exist for seafood, and the state of California has banned the use of the term “organic” for seafood until such standards are created.

Overcapitalization

This occurs when there is more fishing capacity (i.e., more boats, gear, or investment in equipment) than is needed to catch the available fish in an economically efficient and sustainable manner. Overcapitalization poses a threat to fish populations because it can easily lead to overfishing. (Roberts et al. and NRDC)

Overfishing

Overfishing exists when the rate of fishing is greater than the level required to meet the management goal or maximum sustainable yield. In other words, overfishing occurs when a population of fish is caught faster than it can replenish itself through reproduction. (Roberts et al.)

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P

Pelagic

The word “pelagic” is an ancient Greek word for the open ocean or high seas, the area comprising most of the earth’s surface. The word is still used to describe this vast region as well as to describe the creatures that inhabit it (i.e., a pelagic species).

Plankton

Plankton are small plant and animal species that spend at least part of their time on the sea surface. They rely in large part on ocean currents for distribution and transportation. As eggs and larvae, many marine species, such as cod and Dungeness crabs, are planktonic for part of their life cycle. The plankton provide food for many commercially important fish and form the basis of ocean food webs. Some of the largest marine creatures, such as whale sharks and blue whales, eat plankton. Zooplankton are animals and phytoplankton are plants. (Waller)

Pole

Fish caught by this method are first attracted to bait fish thrown into the water; in the midst of the ensuing feeding frenzy, fish are caught on hooks attached to a pole and “poled” aboard. This fishing method is used worldwide to capture surface-swimming tuna such as yellowfin and skipjack.

Polyculture and Integrated Aquaculture

The farming of two or more species in the same aquaculture system; it may involve animals, plants, or plants and animals together. These methods can improve the environmental performance of aquaculture because waste products are used instead of discharged into the environment.

Pond System

One of the earliest forms of aquaculture, ponds can be either natural or artificially constructed. Managing the waste discharges properly can reduce the impact of ponds on the environment. Catfish, carp, and tilapia are most commonly cultured in ponds.

Population

A group of interbreeding organisms that represents the level of organization at which speciation begins. In other words, a population is a group within a species that shares common ecological and genetic features compared to other individuals of that species. (FAO Fisheries Department)

Pot

This is a type of trap designed to catch fish or crustaceans, in the form of cages or baskets. Pots are made of various materials, such as wood, wicker, metal rods, or wire netting, and have one or more openings or entrances. They are usually laid on the bottom, with or without bait, singly or in rows, and are connected by ropes (buoy-lines) to buoys on the surface showing their position.

Precautionary Principle

A proactive method of dealing with the environment that places the burden of proof on those whose activities could harm the environment rather than on the public. It is the opposite of the wait-and-see principle; acting before scientific proof of deleterious effects is applying a precautionary approach. (Norse)

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.

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Q

R

Raceway (Flow-through System)

A flow-through system, or raceway, is a type of aquaculture system in which water is diverted from nearby streams or pumped from wells into concrete troughs or tanks where fish are held. The water flows through a series of raceways before being discharged, usually with some form of wastewater treatment.

Racks and Rafts

These are suspended, or off-bottom, aquaculture methods used to rear mollusks such as oysters. Farming mollusks with these techniques generally results in little environmental impact because no additional feed is needed and little waste is produced. Since the mollusks are not farmed on the ocean bottom, they do not need to be collected by dredging, a method that can damage the seafloor.

Recirculating System

Recirculating systems are closed, or semi-closed, aquaculture systems in which most of the water is recycled through the system and very little is discharged. Water that would otherwise be discharged with wastes is treated and reused within the system. Recirculating systems limit other environmental impacts, such as escapes and disease interactions, but they are costly to operate and are highly dependent on electricity or other power sources.

S

Stock

The technical definition of a stock is an interbreeding sub-population of a species, reproductively isolated to some extent from other populations. Used as a unit for fishery management, however, “stock” refers to a specific population or group of populations of one or more species.

Sustainable Fisheries Act ( also the Magnuson-Stevens Act)

The 1996 Sustainable Fisheries Act amended the habitat provisions of the Magnuson Act. The re-named Magnuson-Stevens Act calls for direct action to stop or reverse the continued loss of fish habitats. Toward this end, Congress mandated the identification of habitats essential to managed species and measures to conserve and enhance this habitat. The Act requires cooperation among NOAA Fisheries, the regional Fishery Management Councils, fishing participants, and Federal and state agencies to protect, conserve, and enhance essential fish habitat. 

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T

Territorial Sea

Traditionally, the territorial sea extended out to three nautical miles from the shore of a coastal nation. Why three nautical miles? This was the distance a cannon could be fired, and thus the distance that a nation could defend itself. With the signing of the Law of the Sea, territorial waters were extended out to twelve nautical miles. In the U.S., the three nautical mile mark is still used as the extent of a state’s jurisdiction; the exceptions to this are Texas and the Gulf coast of Florida, whose territorial seas extend out to nine nautical miles.

Total Allowable Catch (TAC)

The total catch allowed to be taken from a resource in a specified period (usually a year), as defined in the management plan. The TAC may be allocated to the stakeholders in the form of quotas as specific quantities or proportions. (FAO)

Trap

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.

Trawl

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.

Trolling

This is a type of hook-and-line method described above in which several unconnected lines, each hooked and baited, are slowly dragged behind the vessel.

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U

V

W

XYZ

References

National Marine Fisheries Service (NMFS). 1999. Fisheries of the United States, 1998.
Natural Resources Defense Council (NRDC). 1997. Hook Line and Sinking.
Norse, Elliot ed. 1993. Global Marine Biological Diversity.
Roberts, Kenneth, Jerald W. Horst, John E. Roussel, and Joseph A. Shepard. 1991.
Defining Fisheries: A User’s Glossary . [Available online at the American Fishermen’s Research Foundation.]
United Nations Food and Agricultural Organization (UN FAO). 2004. State of World
Fisheries and Aquaculture .
UN FAO. Fisheries Department website. Fisheries Glossary.
Waller, Geoffrey ed. 1996. Sea Life.

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