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Annex 3: Glossary

Adaptive management

A management strategy that can be readily adapted to take account of new knowledge obtained during implementation, including performance assessments.

Alien species

A species occurring in an area outside its historically known natural range as a result of intentional or accidental dispersal by human activities. Also known as Introduced species


Absence of oxygen. A pathological deficiency of oxygen. (The American Heritage Dictionary of the English Language, 2000).


See: Population assemblage.

Associated species

Species that occur with the target species in a given area and may be caught as bycatch during the fishing process.


Living on or in the bottom.


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 (Convention on Biological Diversity, 1992. The variety and variability of living organisms. It takes into account intraspecific genetic variability, the variety of species and their way of life, the diversity of species communities and their interactions, as well as the ecological processes that they influence or realize, the diversity of adaptive strategies and the number of interactions between the organisms and the variables of the environment (Lévèque 1997; FAO 1997).


Produced by living organisms or biological processes. Necessary for the maintenance of life processes. (The American Heritage Dictionary of the English Language, 2000).

Biological potential

A characteristic capacity of all populations, from bacteria to fish, to expand population size, more or less rapidly up to some naturally variable maximum. The expansion capacity of a population is limited by the biogenic capacity of the ecosystem. In fisheries, the term "potential" of a stock refers to its Maximum Sustainable Yield (MSY).


An integrated group of species inhabiting a given area; the organisms within a community influence one another's distribution, abundance and evolution. (A Human Community is a social group of any size whose members reside in a specific locality.) (WRI Biodiversity glossary of terms). See also: Population assemblage.


The interaction among organisms for a necessary resource that is in short supply (Nybakken, 1982). Happens between individuals of a given population or between different populations of the same species which occupy the same ecological niche (intraspecific competition). May happen also between different species with the same or overlapping ecological niches (interspecific competition). It is being argued that, as apical predators, human beings are in competition with marine mammals (Tamura, 2003). Organisms and populations are able to exclude competitors by altering their surroundings through excretion of chemical substances that modify the interactions. In a fished ecosystem, fishers compete for resources with other predators they may exploit (e.g. tunas, sharks) or not (e.g. piscivorous birds and marine mammals).


The management of human use of the biosphere so that it may yield the greatest sustainable benefit to current generations while maintaining its potential to meet the needs and aspirations of future generations; thus, conservation is positive, embracing preservation, maintenance, sustainable utilization, restoration and enhancement of the natural environment (WRI Biodiversity glossary of terms).

Coral bleaching

Anomalous phenomenon occurring in coral reefs through which corals lose their natural colouration and take a whitish color. The discolouration is due to the loss of the microscopic algae living inside their colonies and leads to the loss of photosynthetic capacity of the coral reefs and, eventually, to their death.

Dependent species

A non-target species depending on the target species (e.g. a predator fish depending on a prey).


Regularly migrating between freshwater and seawater. This category includes anadromous and catadromous fishes (e.g. sea lampreys, Anguilla, Alosa, etc. (FishBase Glossary, 2000;


Diversity is a measure of the complexity of an ecosystem and often an indication of its relative age. It is measured in terms of the number of different plant and animal species (Scialabba, 1998). A numerical measure combining the number of species in an area with their relative abundance (Nybakken, 1982). Often called species richness, the diversity of a community is represented by a mathematical expression relating species richness to the relative abundance of a species. For a fixed species richness, the diversity is maximum when the abundance of each species is the same.


A seal of approval (or certification) of a product, process or service complying with a particular set of agreed environmental criteria usually awarded by an impartial third party (certification company). In fisheries, the label informs on the quality of the product itself as well as on the production and management processes.


A voluntary method of certification of environmental quality (of a product) and/or environmental performance of a process based on lifecycle considerations and agreed sets of criteria and standards.

Ecological niche

The function of a species in the ecosystem. For example, the niche of herbivores or the niche of carnivores. The connections between organisms and the ecosystem. Should not be confused with the habitat (Odum, 1975). The ecological niche of an organism depends not only on where it lives (habitat) but also on what it does. By analogy, it may be said that the habitat is the organism's "address", and the niche is its "profession", biologically speaking (Odum, 1959).

Ecological valence

Represents the extent of the variations of the environmental factors which a species can survive in the long run. Thus, a species is an indication of a particular ecological situation. Certain species endure great variations (thermal, eurythermic, saltwater, euryhaline) or no variation (stenothermal).

Endangered species

Species threatened by extinction as a direct or indirect result of human activities,e.g. through habitat degradation, overexploitation, competition with introduced species.


Group of biotic and abiotic variables and their interactions.


The slow aging process of a lake, estuary or bay evolving into a marsh and eventually disappearing. During the later stages of eutrophication, the water body is loaded with excessive concentrations of plant nutrients such as nitrogen and phosphorus, causing excessive algal or plant production. As organic matter accumulates in the water and on the bottom, eutrophication may lead to oxygen depletion, anoxia and massive mortalities. While eutrophication can be a natural process, it can also be provoked or accelerated by human activities adding nutrients (e.g. agriculture fertilizers, manure, urban sewage) to a water body.

Fish-in-Balance index

FiB. A composite indicator of an exploited ecosystem based on the average trophic level and weight of the total catch (see equation below). In the absence of long-term, environmentally-induced changes in species or size composition, changes in FiB may be related to fishing. An increasing trend could indicate, inter alia, a broadening of the resource base through fisheries expansion (e.g. to new and bigger species, farther offshore, at greater depth, etc.). A decreasing trend would indicate overfishing. A stable value would indicate an overall stable (and possibly sustainable) fishery but it may hide trends, including overfishing, in some of the catch components.

where Yi is the catch in year i, TLi the mean trophic level in that catch, Y0 the catch at the start of the series, TL0 the mean trophic level in the catch at the start of the series and TE the mean transfer efficiency between trophic levels. TE has been estimated as 10% in various marine ecosystems (Pauly and Christensen, 1995). Assuming that this estimate applies through the time series the equation simplifies to:

Complied from: Pauly et al. (2000).

Ghost fishing

The continued killing of fish by a fishing gear,e.g. through gilling or entanglement (by a gillnet) or trapping (by a fish trap or pot) after the gear has been lost or voluntarily dumped in the water body.


In general, the activity or process of governing; a condition of ordered rule; those people charged with the duty of governing or the manner/method/ system by which a particular society is governed. In a particular sector (e.g. fisheries), a continuing process through which governments, institutions and stakeholders of the sector and of other interacting sectors, elaborate and adopt appropriate policies, plans and management strategies to ensure sustainable and responsible resource utilization. In the process, conflicting or diverse interests may be accommodated and co-operative action may be taken. The modern use of the term implies change in the meaning (and mode) of government, with: reform of the civil service; greater use of non-governmental organizations (civil society); reduction of public intervention; privatization of public enterprises; encouragement of competition; greater use of markets and quasi-markets to deliver public services; openness of information (transparency), integrity and accountability (auditing); decentralization of responsibilities (local governance) (FAO Glossary, 2002,


Group of organisms that exploit the same resources (share the same food resources) in an ecosystem.


The biological place or position of a population in an ecosystem (Nybakken, 1982). The place where an organism is found (Odum, 1975). The place or type of site where species and communities normally live or grow, usually characterized by relatively uniform physical features or by consistent plant forms (Scialabba, 1998).


The speed at which a population - or group of populations - regains the state in which they were prior to a disturbance (Pearson et al., 1992) or return to the original equilibrium (Barbault, 1997). See also: Resilience.

Introduced species

See: Alien species.


Of or relating to or living in still waters (as lakes or ponds).


Of or relating to or living in moving water (as brooks, rivers, etc.).


Exerting a fishing pressure (fishing intensity) beyond agreed optimum level. (FAO Glossary, 2002; The symptoms of ecosystem overfishing include: reduction in diversity, reduction in aggregate production of exploitable resources, decline in mean trophic level, increase in bycatch, greater variability in abundance of species, greater anthropogenic habitat modification (Hall, 1999). According to Murawski (2000), an ecosystem can be considered to be overfished when cumulative impacts of catches (landings plus discards), non-harvest mortality and habitat degradation result in one or more of the following conditions: (1) Biomasses of one or more of the most important species assemblages fall below minimum biological acceptable levels, such that recruitment is impaired or rebuilding times to MSY are extended; (2) Diversity of communities declines significantly as a result of sequential "fishing down" of stocks; (3) Species selection and harvest rate lead to greater year-to-year variations in populations than would result from lower cumulative harvest rates; (4) Changes in species composition as a result of fishing significantly decrease the resilience or resistance of the ecosystem to perturbations arising from non-biological factors; (5) The harvest rates result in lower cumulative net economical or social benefits than would result from a less intense overall fishing pattern; (6) Harvest of prey species or direct mortalities resulting from operations impair the long-term viability of ecologically important non-resource species (e.g. marine mammals, turtles, sea birds).


Characteristic of a group of stable populations that conserve the same number of species in time (Pimm, 1984; Pimm and Hyman, 1987).


All the individuals of a given species that occupy a given area or ecosystem (from Barbault, 1992). A population is therefore the basic biological functional unit of an ecosystem. The exploitation and eventual overexploitation concerns a population or a group of populations. The unit directly targeted by fishing is the stock, which is not necessarily representative of a population.

Population assemblage

A group of populations living in a given ecosystem, also called community or species assemblage (Lévêque, 1997; Amanieu and Lasserre, 1982). The term community is sometimes considered as more restrictive, referring to a given taxonomic group taken with a given sampling technique.

Protected areas

Designated areas of the ecosystem which are protected by law and regulations with the view to conserving/rehabilitating them and the biodiversity they contain. Protection includes regulation or outright prohibition of human uses.


Relationship between the observed diversity and maximum diversity for a given species richness (Odum, 1975). The distribution of the total number of individuals among the species (Nybakken, 1982).


See: Homeostasis.


The degree of modification of the species composition or a species assemblage after a disturbance. The capacity of species assemblages to resist during a disturbance (Pearson et al., 1992).


See: Species richness.

Species diversity

See: Diversity.

Species richness

The number of species (taxons) occurring inside an ecosystem. A simple listing of the total number of species in a community or trophic level (Nybakken, 1982). SR reflect the capacity of the environment to sustain species, because it is a function of the number of ecological niches and of the habitats' diversity. This concept is important in restocking programmes. See also: Species diversity.


An assemblage of species is stable when it conserves the same number of individuals of each species in the course of time (modified from Connell and Sousa, 1983). A population is stable when it conserves the same number of individuals in the course of time.


The conducting, supervising or managing of something. The careful and responsible management of something entrusted to one's care: stewardship of our natural resources (Webster Dictionary).

Top predators

Predators (carnivores) located at the top of the food chain, feeding on preys located at lower levels in the chain and with no or few predators able to feed on them. Large marine mammals, sharks, tuna, are top predators. Top predators may have a role in top-down control of ecosystem structure and functioning.

Trophic chain

The complex architecture of living creatures interconnected through feeding (predator-prey relationships) from the lower levels of primary productivity (microscopic algae in the plankton) to top predators.

Trophic level

The level of a living creature in the food chain. The phytoplankton is found at the lower levels (bacteria and other microorganisms are at an even lower level). Top predators occupy the highest levels.


Amanieu, M., & Lasserre, G. 1982. Organisation et évolution des peuplements lagunaires. Oceanologica Acta, SP, pp. 201-213

Barbault, R. 1992. Ecologie des peuplements. Structure, dynamique et évolution. Paris. Masson. 200 pp.

Barbault, R. 1997, Ecologie générale - structure and function of the biosphere. Paris. Masson. 286 pp.

Connell, H.J. & Sousa, W.P. 1983, On the evidence needed to judge ecological stability of persistence. American Naturalist, 121: 789-825

FAO. 1997. Fisheries management. FAO Technical Guidelines for Responsible Fisheries, 4: 82 pp.

Hall, S.J. 1999. The effects of fishing on marine ecosystems and communities. London. Blackwell Scientific Publications. 274 pp.

Lévêque, C. 1997. La biodiversité. Que sais-je? Paris. Presse Universitaire de France. 126 pp.

Murawski, S. 2000, Definitions of overfishing from an ecosystem perspective. ICES Journal of Marine Science, 57: 649-658

Nybakken, J.W. 1982. Marine biology. An ecological approach. New York. Harper & Row. 466 pp.

Odum, E.P.1959. Fundamentals of Ecology. Philadelphia. W. B. Saunders and Co. 574 pp.

Odum, E.P. 1975. Ecology. New York. Holt, Rinehart and Wilson

Pauly, D. & Christensen, V. 1995. Primary production required to sustain global fisheries. Nature, 374: 255-257

Pauly, D., Christensen, V. & Walters, C. 2000. Ecopath, Ecosim and Ecospace as tools for evaluating ecosystem impact of fisheries. ICES Journal of Marine Science 57: 697-706

Pearson, T.N., Li, H.W. & Lembertini, G.A. 1992. Influence of habitat complexity on resistence to flooding and resilience of stream fish assemblages. Transactions of the American Fisheries society, 121: 427-436

Pimm, S.L. 1984. The complexity and stability of ecosystems. Nature, 307: 321-326

Pimm, S.L., & Hyman, J.B. 1987. Ecological stability in the context of multispecies fisheries. Canadian Journal of Fisheries and Aquatic Sciences, 44: 84-94

Scialabba, N. (ed.). 1998. Integrated coastal area management and agriculture, forestry and fisheries. FAO Guidelines, 256 pp.

Tamura, T. 2003. Regional assessment of prey consumption and competition by marine cetaceans in the world. In M. Sinclair & G. Valdimarsson, eds. Responsible fisheries in the marine ecosystem, pp. 143-170. Rome, Italy, and Wallingford, UK. FAO and CAB International

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