This glossary has been compiled from various sources including FishBase, Appendix 12 of ICCAT Report 1994-95 (II) and the FAO Atlas. It provides an explanation of many of the technical terms relating to data collection and use which a fisheries manager will be confronted with.
Accuracy of estimates: An indicator of the closeness of an estimated population parameter to the actual population value. Accuracy is generally not known unless cross-checking procedures are conducted from time to time using other survey approaches. It should not be confused with precision which measures the variability of the estimates and can always be computed from the samples.
Active fishing days: Time extrapolating factor used in the estimation of total fishing effort. It is boat/gear specific and defined as the number of days in a reference period (e.g. a calendar month) during which fishing activities are "normal". Usually this variable is defined in reverse manner, that is by subtracting from the calendar days those days known for zero or negligible activity. Definition of active days is in itself a sample-based survey involving several sites and boat/gear types, but it is often specified at minor stratum level by means of empirical knowledge and/or information from the enumerators.
Allowable catch: The catch allowed to be taken from a stock, by a fishery during a specified time period. Often defined as the Total Allowable Catch (TAC), it is often allocated explicitly amongst those having a right of access to the stock. See: Quota.
Artisanal fisheries: Traditional fisheries involving fishing households (as opposed to commercial companies), using relatively small amount of capital and energy, relatively small fishing vessels (if any), making short fishing trips, close to shore, mainly for local consumption. In practice, definition varies between countries, e.g. from gleaning or a one-man canoe in poor developing countries, to more than 20 m trawlers, seiners, or long-liners in developed ones. Artisanal fisheries can be subsistence or commercial fisheries, providing for local consumption or export. Sometimes referred to as small-scale fisheries. See: Subsistence fishery.
Base port: The port from which fishing units operate, irrespective of where they are registered (homeport). The differentiation between base ports and homeports occurs when fishing units migrate from the locations indicated by the frame survey to other sites, usually on a seasonal basis.
Bias in estimates: Estimated population parameters that are systematically smaller (negative bias) or higher (positive bias) than the actual population value. Biases are not traceable unless cross-checking parallel surveys are conducted from time to time. High precision is not an indication of unbiased estimates; in fact extremely high precision (= very low variability in the samples) may well be associated with positively biased samples.
Bio-economic model: An analytical tool to facilitate management decisions. Bio-economic models establish functional relationships between specific characteristics of the natural resource base, (e.g. a fishery resource), and the activities of man to make use of such resource. The formalization of such relationships require certain abstractions from reality, as well as assumptions about the biological processes and human behaviour. To the extent that these assumptions may be partially violated in a specific fishery under study, the results of models should be considered as theoretical and potentially biased. While the reliability of models increases with the validity of the assumptions, there are limits to formalizing and to interpreting the results of highly complex systems.
Biomass: 1) The total weight of the living organisms concerned, whether in a system, a stock, or a fraction of a stock: e.g. plankton biomass in an area, biomass of spawners or of newly recruited fish. 2) Total weight of a resource, a stock, or a component of such stock. Examples: the biomass of all demersal fish on the Georges Bank; the biomass of the cod stock; the spawning biomass (i.e. the weight of mature females) (also standing stock).
Boat Activity Coefficient (BAC): The proportion of fishing units that are expected to be fishing during any given day of the survey period. It is a sample effort parameter and usually expressed in percentage form.
Boat day: A measure of fishing effort; e.g. 10 vessels in a fishery, each fishing for 50 days, would have expended 500 boat-days of effort.
By-catch: Part of a catch of a fishing unit taken incidentally in addition to the target species towards which fishing effort is directed. Some or all of it may be returned to the sea as discards.
Catch: 1) Any activity that results in killing any fish or bringing any live fish on board a vessel. 2) The component of fish encountering fishing gear which is retained by the gear.
Catch per unit effort (CPUE): The amount of catch that is taken per unit of fishing gear, e.g. number of fish per longline hook-months is one way to express CPUE. CPUE can be used as a measure of the economic efficiency of a type of gear, but normally it is used as an index of abundance, i.e. a proportional change in CPUE is hoped to represent the same proportional change in abundance. Nominal CPUE is simply the measure of CPUE from the fishery. However, it is known that there are many factors (including economics, geographical distributions) which may affect CPUE but do not represent changes in abundance. Therefore, CPUEs are often "standardized" using a variety of statistical techniques to remove the effect of those factors which are known not to be related to abundance. Thus, using the standardized CPUE will be more appropriate for an index of abundance. Most assessment analyses (production models, virtual population analyses) use the index of abundance data to fit to calibrate (tune) the models.
Census: A fisheries census is a survey in which the value of each variable for the survey area is obtained from the values of the variable in all reporting units, that are usually fishing households. The primary objective of fisheries censuses is to provide a detailed classification of the fisheries structure of the country. It provides estimates for each household, and therefore, aggregate data for the smallest administrative, political or statistical subdivisions of the country and for classifications of households by size or other subgroups of interest.
Data: Facts that result from measurements or observations.
Data base: A logically structured and consistent set of data that can be used for analysis.
Data Base Management System (DBMS): Application software that stores, maintains, locates and retrieves data for a database.
Data flow: A representational tool that shows how information moves in an organization or process. Special symbols represent different types of data flow.
Data set: A collection of data and accompanying documentation which relate to a specific theme (usually consisting of one or more computer readable files on the same system).
Data validation: Confirmation of the reliability of data through a checking process, usually involving information from an alternative source.
Discard: 1) To release or return fish to the sea, whether or not such fish are brought fully on board a fishing vessel. 2) Part of the catch, which is not retained and is returned to the sea. Discard typically consists of "non-target" species or undersized specimens. While some species (clams, sea stars, etc.) might survive the process, most fish will die. See: By-catch.
Exclusive Economic Zone (EEZ): 1) A zone under national jurisdiction (up to 200-nautical miles wide) declared in line with the provisions of 1982 United Nations Convention of the Law of the Sea, within which the coastal State has the right to explore and exploit, and the responsibility to conserve and manage, the living and non-living resources. 2) The area adjacent to a coastal state which encompasses all waters between: (a) the seaward boundary of that state, (b) a line on which each point is 200 nautical miles (370.40 km) from the baseline from which the territorial sea of the coastal state is measured (except when other international boundaries need to be accommodated), and (c) the maritime boundaries agreed between that state and the neighbouring states.
Fillet: A slice of meat without bones, cut out for human consumption.
Fisher: A person (male or female) participating in a fishery (in preference to the previously used term 'fisherman'). An individual who takes part in fishing conducted from a fishing vessel, platform (whether fixed or floating) or from the shore.
Fishery: 1) The sum (or range) of all fishing activities on a given resource (e.g. a hake fishery or shrimp fishery). It may also refer to the activities of a single type or style of fishing (e.g. beach seine fishery or trawl fishery). The fishery can be artisanal, or/and industrial, commercial, subsistence, and recreational, and can be annual or seasonal. 2) Activity of catching fish, from one or more stocks of fish, that can be treated as a unit for purposes of conservation and management and that is identified on the basis of geographic, scientific, technical, recreational, social or economic characteristics, and/or method of catch. See: Fishing.
Fishery-independent: Characteristic of information (e.g. stock abundance index) or an activity (e.g. research vessels survey) obtained or undertaken independently of the activity of the fishing sector. Intended to avoid the biases inherent to fishery-related data.
Fish stock: The living resources in the community or population from which catches are taken in a fishery. Use of the term fish stock usually implies that the particular population is more or less isolated from other stocks of the same species and hence self-sustaining. See: Fishery resource
Fishery management: The integrated process of information gathering, analysis, planning, decision-making, allocation of resources and formulation and enforcement of fishery regulations by which the fishery management authority controls the present and future behaviour of interested parties in the fisheries, in order to ensure the continued productivity of the living resources.
Fishery resource: Any stock of aquatic living animals (except those specifically prohibited by law) which can be caught by fishing, and their habitat.
Fishing: Any activity, other than scientific research conducted by a scientific research vessel, that involves the catching, taking, or harvesting of fish; or any attempt to do so; or any activity that can reasonably be expected to result in the catching, taking, or harvesting of fish and any operations at sea in support of it (Modified from US Department of Commerce, 1996).
Fishing effort: 1) The amount of fishing gear of a specific type used on the fishing grounds over a given unit of time e.g. hours trawled per day, number of hooks set per day or number of hauls of a beach seine per day. 2) The overall amount of fishing (usually per unit of time) expressed in units such as: boat days on the fishing ground, number of traps, or trawl hauls, or (gillnet length x soaking time), etc. The effort may be nominal, reflecting the simple total of effort units exerted on a stock in a given time period. It may also be standard or effective when corrected to take account of differences in fishing power and efficiency and ensure direct proportionality with fishing mortality. Relates usually to a specific fishery and gear. If more than one gear is considered, standardization in relation to one of them is necessary. For biologists, a good measure of fishing effort should be proportional to fishing mortality. For economists it should be proportional to the cost of fishing.
Fishing industry: Includes both recreational, subsistence and commercial fishing, and the harvesting, processing, and marketing sectors.
Fishing intensity: Effective fishing effort per unit area. It is proportional to fishing mortality
Fishing mortality: A mathematical expression of the rate of deaths of fish due to fishing. See: Natural mortality, Total mortality rate.
Fishing vessel: Any vessel, boat, ship, or other craft that is used for, equipped to be used for, or of a type that is normally used for the exploitation of living aquatic resources or in support of such activity. This definition may include any vessel aiding or assisting one or more vessels at sea in the performance of any activity relating to fishing, including, but not limited to, preparation, supply, storage, refrigeration, transportation, or processing (e.g. mother ships).
Flag State: State having registered a vessel under the national flag.
Fleet: The aggregation of units of any discrete type of fishing activity utilising a specific resource. Hence, for example, a fleet may be all the purse seine vessels in a specific sardine fishery, or all the fishers setting nets from the shore in a tropical multispecies fishery.
Frame survey: A complete description of the structure of the primary fishery sector including an inventory of ports, landing places, number and type of fishing units (boats and gears), and a description of fishing and landing activity patterns, fish distribution routes, processing and marketing patterns, supply centres for goods and services, etc.
Gear: Any tools used to catch fish, such as hook and line, trawls, gill nets, traps, spears, etc.
Geographic Information System (GIS): An information system that stores and manipulates data which is referenced to locations on the earth's surface, such as digital maps and sample locations.
Geo-referenced data: Data which is connected to a specific location on the earth's surface.
Home port: Refer to base port described above. Boat and gear activities are sampled from homeports or base ports, in contrast to catches and species composition, prices, etc. that are sampled at landing sites.
Household: A basic unit for socio-cultural and economic analysis. It includes all persons, kin and non-kin, who live in the same dwelling and share income, expenses and daily subsistence tasks. The concept of household is based on the arrangements made by persons, individually or in groups, for providing themselves with food or other essentials for living. A household may be either (a) a one-person household, that is, a person who makes provision for his or her own food or essentials for living without combining with any other person to form part of a multiperson household, or (b) a multiperson household, that is, a group of two or more persons living together who make common provision for food or other essentials of living. The persons in the group may pool their incomes and have a common budget to a greater or lesser extent; they may be related or unrelated persons or a combination of both. Households usually occupy the whole, part of, or more than one housing unit but they may also be found living in camps, boarding houses or hotels or as administrative personnel in institutions, or they may be homeless. Households consisting of extended families that make common provision for food or of potentially separate households with a common head, resulting from polygamous unions, or households with vacation or second homes may occupy more than one housing unit. Homeless households are defined as those households without a shelter that would fall within the scope of living quarters. A household also includes those persons who normally reside with the other members of the household but are away temporarily (for less than one year), e.g. full-time students or those engaged in seasonal migratory labour.
Incidental Catch: See: By-catch.
Index of abundance: A relative measure of the abundance of a stock; e.g. a time series of catch per unit of effort data.
Indicator: A variable, pointer, or index. Its fluctuation reveals the variations in key elements of a system. The position and trend of the indicator in relation to reference points or values indicate the present state and dynamics of the system. Indicators provide a bridge between objectives and action (FAO, 1999. FAO Technical Guidelines for Responsible Fisheries Development and Use of Indicators for Sustainable Development of Marine Capture Fisheries, in press).
Information system: A structured set of processes, people and equipment for converting data into information.
Landing price: Price for a product at the landing point, not taking account of any transportation or handling costs. Equivalent to the "farm gate" price for aquaculture.
Landing site: Location at which boats land their catch. A landing site may be the same as the homeport or base port but it can also be different. Boat and gear activities are sampled from homeports or base ports, in contrast to catches and species composition, prices, etc. that are sampled at landing sites.
Landings: Weight of the catch landed at a wharf or beach.
Limit Reference Point (LRP): Indicates the limit beyond which the state of a fishery and/or a resource is not considered desirable. Fishery development should be stopped before reaching it. If an LRP is inadvertently reached, management action should severely curtail or stop fishery development, as appropriate, and corrective action should be taken. Stock rehabilitation programmes should consider an LRP as a very minimum rebuilding target to be reached before the rebuilding measures are relaxed or the fishery is re-opened. See: Reference point, Target Reference Point.
Logbook: A record of the fishing activity registered sistematically by the fisher, including catch and its species composition, the corresponding effort, and location. In many fisheries completion of logbooks is a compulsory requirement of a fishing licence.
Major stratum: Conventional name describing various types of population groupings that are already in place and imposed on a data collection programme. They constitute standard aggregating levels of derived estimates for reporting purposes. Estimates are always produced at minor stratum and not at major stratum level.
Management authority: The legal entity which has been assigned by a State or States with a mandate to perform certain specified management functions in relation to a fishery, or an area (e.g. a coastal zone). Generally used to refer to a state authority, the term may also refer to an international management organisation.
Management objective: A formally established, more or less quantitative target that is actively sought and provides a direction for management action. For example, achieving a 40% reduction in fleet capacity, or ensuring a competitive income for individual fishers.
Minor stratum: Conventional name describing various types of logical population partitioning into homogeneous population sub-sets defined by the survey planner with the purpose of increasing the precision of estimated population parameters. Estimates are always produced at minor stratum level.
Monitoring: The collection of information for the purpose of assessment of the progress and success of a land use (or fishery management) plan. Monitoring is used for the purpose of enforcement and of revising the original plan, or to gather information for future plans.
Nationality of catch: The flag of the vessel performing the essential part of the operation catching the fish, should be considered the paramount indication of the nationality assigned to the catch data and this indication overridden only when one of the following arrangements between a foreign flag vessel and the host country exists: (a) the vessel is chartered by the host country to augment its fishing fleet; or (b) the vessel fishes for the country by joint venture contract or similar agreements (as opposed to the ad hoc practice of a vessel selling catches to a foreign vessel or landing catches at a foreign port) and the operation of such vessel is an integral part of the economy of the host country. When governments negotiate joint ventures or other contracts in which vessels of one country land their catches at ports of another country or unload their catches to vessels of another country and the one of the above-mentioned criteria is applicable, the assignment of nationality to such catches and landings data should be specified in the agreement.
Natural mortality: Deaths of fish from all causes except fishing (e.g. ageing, predation and disease). It is often expressed as an annual rate that indicates the percentage of fish dying in a year; e.g. a natural mortality rate of 0.2 implies that approximately 20% of the population will die in a year from causes other than fishing. Scientists use the instantaneous natural mortality rate, M, which may also be split into one part due to predation and the other due to all other natural causes (disease, ageing). See: Fishing mortality, Total mortality rate.
Nominal catch: The sum of the catches that are landed (expressed as live weight equivalent). Nominal catches do not include unreported discards and may differ considerably from the actual catch.
Observer: Any certified person serving in the capacity of an observer employed by the Management Authority, either directly or under contract. Usually embarked on large fishing vessels (principally but not exclusively foreign vessels), observers are responsible for monitoring fishing operations (e.g. areas fished, fishing effort deployed, gear characteristics, catches and species caught, discards, etc.). They may or may not be part of the enforcement system.
Observer data: Fisheries information collected on-board fishing vessels by independent observers.
Performance: Accomplishment; fulfilment; functioning, usually with regard to effectiveness. Indicators of performance will be interpreted in relation to reference points and objectives.
Policy: The course of action for an undertaking adopted by a government, a person or another party. Instruments that exist to support policy and tools used to achieve policy objectives comprise some or all of the following: societal instruments, economic and command and control instruments, direct government involvement and institutional and organisational arrangements. It is to be mentioned that although law may be used as a policy instrument, there are cases where law may impose constraints on what policies may be adopted. For example, if the Constitution states that the shore is the patrimony of the nation or requires the payment of compensation for the expropriation of the land, this would restrict the policies which could be adopted for Integrated Coastal Area Management (ICAM).
Precautionary approach: 1) Set of measures taken to implement the precautionary principle. 2) A set of agreed cost-effective measures and actions, including future courses of action, which ensures prudent foresight, reduces or avoids risk to the resource, the environment, and the people, to the extent possible, taking explicitly into account existing uncertainties and the potential consequences of being wrong.
Quota: A share of the Total Allowable Catch (TAC) allocated to an operating unit such as a country, a vessel, a company or an individual fisherman (individual quota) depending on the system of allocation. Quotas may or may not be transferable, inheritable, and tradable. While generally used to allocate total allowable catch, quotas could be used also to allocate fishing effort or biomass.
Recreational fishing: Any fishing for which the primary motive is leisure rather than profit, the provision of food or the conduct of scientific research. and which may not involve the sale, barter, or trade of part or all of the catch.
Reference point: 1) An estimated value derived from an agreed scientific procedure and/or model, which corresponds to a specific state of the resource and of the fishery, and that can be used as a guide for fisheries management. Reference points may be general (applicable to many stocks) or stock-specific. 2) A reference point indicates a particular state of a fishery indicator corresponding to a situation considered as desirable (Target Reference Point) or undesirable and requiring immediate action (Limit Reference Point).
Resources: Biological resources include genetic resources, organisms or parts thereof, populations or any other biotic component of ecosystems with actual or potential use of value for humanity. fishery resources are those resources of value to fisheries.
Responsible fisheries: The concept "encompasses the sustainable utilisation of fishery resources in harmony with the environment; the use of capture and aquaculture practices which are not harmful to ecosystems, resources and their quality; the incorporation of added value to such products through transformation processes meeting the required sanitary standards; the conduct of commercial practices so as to provide consumers access to good quality products" (International Conference on Responsible Fishing, Cancun, Mexico, 1992).
Round weight: The weight of the whole fish before processing or removal of any part.
Sample design: The sample design of a sample survey refers to the techniques for selecting a probability sample and the methods to obtain estimates of the survey variables from the selected sample.
Spawning stock: Mature part of a stock responsible for the reproduction.
Spawning Stock Biomass (SSB): The total weight of all sexually mature fish in the population (both males and females). This quantity depends on the abundance of year classes, the exploitation pattern, the rate of growth, both fishing and natural mortality rates, the onset of sexual maturity, and environmental conditions.
Species group: Group of species considered together, often because they are difficult to differentiate without detailed examination (very similar species) or because data for the separate species are not available (e.g. in fishery statistics or commercial categories).
Stakeholders: A large group of individuals and groups of individuals (including governmental and non-governmental institutions, traditional communities, universities, research institutions, development agencies and banks, donors, etc.) with an interest or claim (whether stated or implied) which has the potential of being impacted by or having an impact on a given project and its objectives. Stakeholder groups that have a direct or indirect stake can be at the household, community, local, regional, national, or international levels.
State of the stock: An appreciation of the situation of a stock, usually expressed as: protected, under-exploited, intensively exploited, fully exploited, over-exploited, depleted, extinct or commercially extinct.
Stock: 1) In theory, a unit stock comprises all the individuals of fish in an area, which are part of the same reproductive process. It is self-contained, with no emigration or immigration of individuals from or to the stock. On practical grounds, however, a fraction of the unit stock is considered a "stock" for management purposes (or a management unit), as long as the results of the assessments and management remain close enough to what they would be on the unit stock. 2) A group of individuals in a species occupying a well defined spatial range independent of other stocks of the same species. Random dispersal and directed migrations due to seasonal or reproductive activity can occur. Such a group can be regarded as an entity for management or assessment purposes. Some species form a single stock (e.g. southern bluefin tuna) while others are composed of several stocks (e.g. albacore tuna in the Pacific Ocean comprises separate Northern and Southern stocks). The impact of fishing on a species cannot be determined without knowledge of this stock structure.
Stock assessment: The process of collecting and analyzing biological and statistical information to determine the changes in the abundance of fishery stocks in response to fishing, and, to the extent possible, to predict future trends of stock abundance. Stock assessments are based on resource surveys; knowledge of the habitat requirements, life history, and behaviour of the species; the use of environmental indices to determine impacts on stocks; and catch statistics. Stock assessments are used as a basis to assess and specify the present and probable future condition of a fishery.
Straddling stock: Stock which occurs both within the EEZ and in an area beyond and adjacent to EEZ (Article 63(2) of UNCLOS).
Subsistence fishery: A fishery where the fish caught are consumed directly by the families of the fishers rather than being bought by middle-(wo)men and sold at the next larger market.
Survey design: The overall survey design of a probability survey refers to the definitions and the established methods and procedures concerning all phases needed for conducting the survey: the sample design, the selection and training of personnel, the logistics involved in the management of the field force and the distribution and receipt of survey questionnaires and forms, and the procedures for data collection, processing and analysis.
Sustainable development: 1) "Development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs" (World Commission on Environment and Development, 1987). 2) "Management and conservation of the natural resource base, and the orientation of technological and institutional change in such a manner as to ensure the attainment of continued satisfaction of human needs for present and future generations. Such sustainable development conserves (land) water, plants and (animal) genetic resources, is environmentally non-degrading, technologically appropriate, economically viable and socially acceptable" (FAO Council in 1991).
Sustainable use: The use of components of biological diversity in a way and at a rate that does not lead to the long-term decline of biological diversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations.
Sustainable yield: The number or weight of fish in a stock that can be taken by fishing while maintaining the stock's biomass at a steady level from year to year, assuming that environmental conditions remain the same. Sustainable yields can take all sorts of values from very low in underexploited or overexploited fisheries to very high in properly exploited ones. Difficult to achieve in practice due to environmental fluctuations.
Target Reference Point (TRP): Corresponds to a state of a fishery and/or a resource which is considered desirable. Management action, whether during a fishery development or a stock rebuilding process should aim at bringing and maintaining the fishery system at this level. In most cases a TRP will be expressed in a desired level of output for the fishery (e.g. in terms of catch) or of fishing effort or capacity and will be reflected as an explicit management objective for the fishery. See: Limit Reference Point, Reference point.
Target species: Those species that are primarily sought by the fishermen in a particular fishery. The subject of directed fishing effort in a fishery. There may be primary as well as secondary target species.
Total Allowable Catch (TAC): 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.
Total mortality rate (Z): The combined effect of all sources of mortality acting on a fish population. This is conveniently expressed in terms of instantaneous mortality rates because the total instantaneous mortality rate is simply the sum of the instantaneous fishing and natural mortality rates. For example, the total instantaneous mortality rate that is occurring when the instantaneous fishing mortality rate is 0.3 and the instantaneous natural mortality rate is 0.2 would be 0.5. See: Fishing mortality, Natural mortality.
Transshipment: Act of transferring the catch from one fishing vessel to either another fishing vessel or to a vessel used solely for the carriage of cargo.
Trash fish: Fish with little or no commercial value and not sorted by species before landing. Usually part of the trawlers' by-catch. It can be used for aquaculture, fishmeal production and in many developing countries, for human consumption.
Variable: Anything changeable. A quantity that varies or may vary. Part of a mathematical expression that may assume any value (Compton's Encyclopaedia, 1995)
Vessel Monitoring System (VMS): VMS provides monitoring agencies with accurate locations of fishing vessels that are participating in the VMS. It tells the monitoring agency see new guidelines.
Yield: Catch in weight. Catch and yield are often used interchangeably.