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Abbreviations and Definitions

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A glossary of marine and fisheries terminology (abbreviations and definitions). The glossary is in alphabetical order. Navigation is provided by using the first letter from the list below.

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Abiotic
The non-living parts of the environment, e.g. rocks, climate, and pressure, that affect ecological functions.
Abundance
The number of individuals in a certain stock or population.
Acceptable levels
Management issues revolve around deciding what is an acceptable level of fishing. This can be looked at in two ways; biological overfishing or economic overfishing. Also see the entry for overfishing.
Aquaculture
A generic term describing cultivation of marine / freshwater species. This includes both plants and animals.

Benthic
Living on or in the seabed.
Benthos
Organisms dwelling on, or attached to, the seabed.
Biodiversity
The abundance and variety of species, their genetic make-up, and the ecosystems and natural communities they all occur in. Defined by the UN-CBD as "the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems." See the illustrated page on marine biodiversity.
Biologically extinct
When a species population density is so low that no partners are available for mating purposes.
Biological overfishing
Biological overfishing occurs when fishing mortality has reached a level where the stock biomass has a negative growth. Also see the entry for acceptable levels.
Biomass
The accumulative total weight of all living organisms in a stock or resource.
Biotic
The living parts of the environment, e.g. plants, animals and fungi, that affect ecological functions.
Bottom trawling
A fishing method -also known as Benthic trawling- that involves dragging trawl nets along the sea floor. A highly non-selective fishing method with a large amount of bycatch and destruction in the trawler area. Can be performed by either a single or a combination of ships.
Bycatch
Unwanted, non-target, marine species caught while fishing for another species.

Catch share
A general term for several fishery management strategies that allocate a specific portion of the total allowable fishery catch to individuals, cooperatives, communities, or other entities. Each recipient of a catch share is directly accountable to stop fishing when its exclusive allocation is reached. Often the term Individual fishing quota is used.
Common Fisheries Policy
The fisheries policy of the European Union (EU). It sets quotas for which member states are allowed to catch what amounts of each type of fish.
Commercially unviable
The fishing effort -taking in account costs, subsidies, offset prices etc- needed being too high to make an economic profit.

Discards
Marine species thrown back after capture. Normally, most of the discards can be assumed not to survive.

Economic overfishing
Economic overfishing occurs when fish are removed from the fishery so quickly that the profitability of the fishery is sub-optimal. Also see the entry for acceptable levels.
Ecosystem
All the organisms in an area, along with the non-living (or abiotic) factors with which they interact. A biological community within a physical environment.
Ecosystem overfishing
A type of overfishing. When the balance of the ecosystem is altered due to overfishing. Declines in the abundances of large predatory species declines and in turn small forage type species increase in abundance, causing a shift in the balance of the ecosystem towards smaller species of fish. "Fishing down the food-chain" is well known analogy for this.

Fishing capacity
A concept not yet rigorously defined, and there are substantial differences of opinion as to how it should be defined and estimated. However, a working definition is the quantity of fish that can be taken by a fishing unit, for example an individual, community, vessel or fleet, assuming that there is no limitation on the yield from the stock.

Growth overfishing
A type of overfishing. When fish are harvested at an average size that is smaller than the size that would produce the maximum yield per recruit. This makes the total yield less than it would be if the fish were allowed to grow to a reasonable size. It can be countered by reducing fishing mortality to lower levels and increasing the average size of the fish harvested to a length that will allow maximum yield per recruit.

Harvest Control Rules
A model to predict acceptable levels.> Harvest Control Rules (HCR) is a variable over which the fisheries management organisation has some direct control as a function of some indicator of stock status. Constant catch and constant fishing mortality are two types of simple harvest control rules. Also see the entries for precautionary principle.

Illegal fishing
Fisheries conducted by national or foreign vessels in waters under the jurisdiction of a State but without the permission of that State (or in contravention of its laws and regulations). This also applies to fisheries flying the flag of States operating in contravention to the conservation and management measures adopted by an RFMO. Also see the entry for IUU-fishing.
IUU-fishing
Illegal, unreported and unregulated fishing is a group of fisheries activities that respect neither national boundaries nor international attempts to manage high seas resources. These usually thrive where governance is weak and where countries fail to meet their international responsibilities and put unsustainable pressure on fish stocks, marine wildlife and habitats, subverts labour standards and markets. Experts estimate that up to 22 % of total fisheries production is from IUU. These types of fisheries are often labelled Pirate fishing; incentives are mostly economic with the species targeted usually over-exploited, in short supply and thus of high value. Also see the entries for illegal fishing, unreported fishing and unregulated fishing.

Maximum Sustainable Yield, MSY
A concept often used in fisheries management describing the theoretical the largest yield (catch) that can be taken from a stock of a species over an indefinite period. In many modern fisheries management models the MSY occurs at 30% of the unexploited population size. In real world situations misuse of this concept in fisheries management has lead to the collapse of many fisheries as variables as size, reproductive status, age of the animals, the surrounding ecosystem and bycatch / IUU are often not taken in account.

Overfishing
Catching too much fish for the system to support. Also see the entries for ecosystem overfishing, growth overfishing and recruit overfishing. See: what is overfishing.

Pelagic trawling
A fishing method that involves towing a trawl net trough the water column. Can be performed by either a single or a combination of ships.
Precautionary principle
The precautionary principle (also called precautionary approach) states that if an action or a policy has a suspected risk of causing harm to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those taking the action: ("you can fish, but only if you can proof it will not do any harm"). Many fish stocks are managed by this system (through Harvest Control Rules). In classifying endangered species, the precautionary principle means that if there is doubt about an animal's exact conservation status, the one that causes the strongest protective measures to be realized should be chosen.

Quota
A dedicated portion of a species-specific total allowable catch allocated to a country, fishing-group or an individual fishermen. These are typically given out by weight and for a set time period. Also see Catch share.

Recruit overfishing
A type of overfishing. When the mature adults, or spawning biomass, population is depleted to a level where it no longer has the reproductive capacity to replenish itself. There are not enough adults to produce offspring. Increasing the spawning stock biomass to a target level is the approach taken by managers to restore an overfished population to sustainable levels. This is generally accomplished by placing moratoriums, quotas and minimum size limits on a fish population.
Regional Fisheries Management Organisation, RFMO
International organisations dedicated to the management of fishery resources in a particular region of international waters or of a highly migratory species. Also called Regional Fisheries Organisation (RFO). These are often highly political organisations where economic and political powers overrule scientific management advice. Examples of RFMOs are the International Commission for the Conservation of Atlantic Tunas (ICCAT.int) and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR.org).

Trawling
See bottom trawling and pelagic trawling.

UN-CBD
The United Nations Convention on Biological Diversity. See: biodiv.org.
Underfishing
A management concept where deliberately taking significantly less than the MSY is a means to increase fish stocks in the long run and thus maintain a sustainable fisheries.
Unreported fishing
Fishing activities which have not been unreported, or have been misreported, to the relevant national authority or regional organisation (RFMO), in contravention of applicable laws and regulations. Also see the entry for IUU-fishing.
Unregulated fishing
Fishing activities in the area of application of a relevant RFMO that are conducted by vessels without nationality, or by those flying the flag of a State not party to that organisation. It also applies to fishing activities in areas or for fish stocks for which there are no applicable conservation or management measures and where such fishing activities are conducted in a manner inconsistent with State responsibilities for the conservation of living marine resources under international law. Also see the entry for IUU-fishing.