Biological reference point

Biological reference points are different indicators that provide a standard for comparison. They are used to inform fisheries managers about stock’s status relative to various management objectives. BRPs are often based on fishing mortality rates, biomass, or the maintenance of adequate recruitment to the stock. Some of them are the target reference point and the limit reference point.

Biomass for the maximum sustainable yield

The biomass that would provide the highest long‑term average catch (or maximum sustainable yield, MSY) of a fish stock.

Biomass (total)

The total weight or volume of a stock of fish.


Conservation and management measures

Measures adopted by T-RFMOs to manage tuna stocks. Sometimes referred to as “Resolutions” or “Recommendations”.

Coastal states

A state whose territory is surrounded by sea, at least, in some places, and consequently has jurisdiction over particular maritime areas and resources, including fishing. In this context, this term is commonly used in contrast to distant water fishing nations (DWFNs).

Catch per unit of effort

The quantity of fish caught (in number or in weight) with one standard unit of fishing effort (e.g., number of fish taken per 1,000 hooks per day, or weight of fish taken per hour of trawling). CPUE is often considered an index of fish biomass (or abundance). Sometimes referred to as catch rate.


Distant water fishing nations

A term used to describe those countries that fish outside their own territories and usually extend their range of action to faraway places. The establishment of the economic exclusive zones regulated the access to these areas in order to avoid conflicts for the use of marine resources between coastal and distant nations.


Exclusive economic zone

Sea zone prescribed by the United Nations Convention on the Law of the Sea in 1982 over which a state has special rights regarding the exploration and use of marine resources. It stretches from the baseline out to 200 nautical miles from its coast.

Electronic monitoring system

An advanced fishing-monitoring system installed in fishing vessels that integrates a set of components for continuously recording information during fishing trips using video technology. EMS largely consists of cameras integrated with GPS that register exact positions, and sensors that start recording when they detect specific actions on the vessels —such as setting or hauling fishing gear. The camera and sensor systems do not allow external manipulation of data. These systems, if properly designed and installed, can be considered a reliable and accurate method to estimate catches onboard vessels and to independently assess vessel compliance with regulations.

Endangered, threatened or protected species

Designation used in some countries for vulnerable species such as marine mammals, sea turtles, and others.


(FFA) Pacific Islands Forum Fisheries Agency

An advisory body providing expertise, technical assistance, and other support to its Pacific Island members. FFA helps countries to sustainably manage, control and develop the tuna fishery resources that fall within their 200-mile exclusive economic zones (EEZs).

Fishing effort

A measure of the resources used to harvest in a fishery. The measure of effort appropriate for a fishery depends on the fishing methods used and the management arrangements. Common measures include the number of vessels, the number of hooks set, and the number of fishing days or nights.

Fishing mortality at the maximum sustainable yield

The level of fishing intensity that, if applied constantly year after year, would result in the maximum sustainable yield (MSY).

Flag of convenience

A business practice under which commercial vessel owners register their ships in a nation that they do not necessarily belong to, flying the civil ensign of that state on their ships. This is often considered a suspicious practice since it is normally used to reduce operating costs or evade rules and regulations of the home nation.

Fishing capacity

An indicator used to assess the fishing pressure caused by a fishing fleet. Fishing capacity can be expressed in terms of tonnage and/or engine power, and sometimes as the number of vessels and their average size. Larger vessels are generally considered to lead to more fishing pressure because of the type of gear, its level of activity, and the geographical coverage that these vessels can reach.


Harvest control rules

Set of well-defined management actions that describe how the harvest is to be managed (e.g., catch or effort-related limits) based on the state of a specified indicator(s) of stock status. Changes in stock status indicators must be measured against appropriate biological reference points inferred from monitoring data or models.


Illegal, unreported and unregulated (IUU)

IUU fishing is a broad term that captures a wide variety of fishing activity. IUU fishing is found in all types and dimensions of fisheries; it occurs both on the high seas and in areas within national jurisdiction. It concerns all aspects and stages of the capture and utilisation of fish, and it may sometimes be associated with organized crime.

Illegal fishing: 

  • conducted by national or foreign vessels in waters under the jurisdiction of a State, without the permission of that State, or in contravention of its laws and regulations;
  • conducted by vessels flying the flag of States that are parties to a relevant regional fisheries management organisation but operate in contravention of the conservation and management measures adopted by that organisation and by which the States are bound, or relevant provisions of the applicable international law; or
  • in violation of national laws or international obligations, including those undertaken by cooperating States to a relevant regional fisheries management organization.

Unreported fishing:

  • which have not been reported, or have been misreported, to the relevant national authority, in contravention of national laws and regulations; or
  • are undertaken in the area of competence of a relevant regional fisheries management organisation which have not been reported or have been misreported, in contravention of the reporting procedures of that organisation.

Unregulated fishing: 

  • in the area of application of a relevant regional fisheries management organization that are conducted by vessels without nationality, or by those flying the flag of a State not party to that organization, or by a fishing entity, in a manner that is not consistent with or contravenes the conservation and management measures of that organization; or
  • in areas or for fish stocks in relation to 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.

IUU fishing undermines national and regional efforts to conserve and manage fish stocks and, as a consequence, inhibits progress towards achieving the goals of long-term sustainability and responsibility. Moreover, IUU fishing greatly disadvantages and discriminates against those fishers that act responsibly, honestly and in accordance with the terms of their fishing authorizations. If IUU fishers target vulnerable stocks that are subject to strict management controls or moratoria, efforts to rebuild those stocks to healthy levels will not be achieved, threatening marine biodiversity, food security for communities who rely on fisheries resources for protein and the livelihoods of those involved in the sector.


Limit reference point

A type of biological reference point that defines the beginning of the “danger zone” for a stock, i.e., the point beyond which fishing is no longer sustainable for the stock.


Management procedure

A pre-agreed framework for recommending or making fisheries management decisions, such as setting catch limits, that is designed to achieve specific management objectives. A fully developed MP specifies which monitoring data will be collected, how the data will be analyzed and what harvest control rule(s) will be applied, and has been simulation tested to determine likely performance across a range of uncertainties (e.g., via MSE).

Monitoring, control and surveillance

A set of tools used to monitor and control fishing activities

Management strategy evaluation

A simulation‐based, analytical framework used to evaluate the performance of multiple candidate management procedures relative to the pre-specified management objectives, or to determine how well an existing strategy performs. An MSE considers the uncertainty arising from stock assessments (e.g., confidence intervals on parameters and quantities of interest) when determining annual catch levels.


Observer coverage

The amount of observer effort (number of human observers or electronic monitoring devices) set for a fleet, so that it is sufficient to ensure that fisheries comply with fishing rules and regulations. Observer coverage also is used to record data for scientific and management purposes representatively and accurately.

Observer programs (or programmes)

An important component for fisheries management that consists of monitoring commercial fishing activities at sea, and reporting key information — such as data on catch, effort and bycatch — for scientific, compliance and management purposes. An observer program can include trained human observers who watch carefully and record what is happening onboard or electronic monitoring devices.


A form of over-exploitation of fishery resources where the fishing intensity exceeds the capacity of a stock to maintain a sustainable ecological level. In overfishing, the fish stock is diminished to such an extent that the remaining adult fish are not able to replenish their population through natural reproduction. Prolonged overfishing rates lead to depletion of fish populations and the collapse of fisheries.


The state of a stock that has been exploited beyond an ecologically sustainable limit and whose population size has become too low to ensure safe reproduction. Overfished stocks can be managed under a rebuilding plan that, over time, returns the population to optimal ecological levels. The stock may remain overfished for some time even though fishing pressure might be reduced or suppressed.


Port States Measures Agreement

A FAO agreement adopted by the FAO Conference in 2009. The main purpose of the Port States Measures Agreement (PSMA) is to prevent, deter and eliminate illegal, unreported and unregulated (IUU) fishing through the implementation of robust port state measures. The Agreement envisages that parties, in their capacities as port states, will apply the Agreement in an effective manner to foreign vessels when seeking entry to ports or while they are in port. The application of the measures set out in the Agreement will, inter alia, contribute to harmonized port state measures, enhanced regional and international cooperation and block the flow of IUU-caught fish into national and international markets.

Parties to the Nauru Agreement (PNA)

A group of eight countries (Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Solomon Islands and Tuvalu) that controls the largest tropical tuna fishery in the world.


Spawning stock biomass

An indicator of the status of the stock and its reproductive capacity. It can be defined as the combined weight of all individuals in a fish stock (usually females only) that have reached sexual maturity and are capable of reproducing.


Biological unit of one species forming a group of similar ecological characteristics which is the subject of assessment and management in fisheries management studies. T-RFMOs recognize 23 stocks of major commercial tunas.

Supply vessel

A vessel that provides assistance to other fishing vessels, such as fuel supply, fish storage, refrigeration or processing, and/or periodic transportation of catches to shore. Some fleets use supply vessels to plant and check FADs and to maintain them. A supply vessel can work with one purse seiner or be shared by a group. Such activity allows a fishing vessel to access a larger number of FADs than it would otherwise be able to maintain.


Temperate tuna species

Tuna species that inhabit cold-temperate waters around 10°C, although they can also be found in warmer waters of the subtropical regions. This group includes the three species of bluefin tuna (Atlantic bluefin, Pacific bluefin, and Southern bluefin) and albacore tuna.

Threshold reference point

A threshold reference point can be used in a harvest control rule as an “early warning” indicator, to help the fishery remain close to the target reference point and reduce the probability that the limit reference point (LRP) would be exceeded.

Tropical tuna species

Tuna species that inhabit warm-temperate tropical and subtropical waters, with temperatures generally greater than 18°C, (although they can dive in colder waters). This group includes skipjack, yellowfin, and bigeye tuna.

Target reference point

A type of biological reference point that defines the level of biomass and fishing pressure that would allow optimal harvests, respecting both ecological and socioeconomic objectives for the fish stock or fishery. It is an indicator that establishes the target fishery state that should be achieved and maintained on average.


The transfer process of fish or fish products at sea or in port, from one fishing vessel to either another fishing vessel — or to a vessel used solely for the carriage of cargo, for further transport. At-sea transshipments are of special concern in fishery management since, if not properly monitored, they can complicate the collection of accurate data and the traceability of product, creating a fertile environment for illegal, unreported, and unregulated fishing activities.



Regional Fisheries Management Organisations (RFMOs) are international organisations formed by countries with fishing interests in an area. Some of them manage all the fish stocks found in a specific area (except the highly-migratory species), while others principally focus on highly-migratory species, notably tuna, sharks and billfish; these “tuna- RFMOs” are the ones we are interested in engaging.

The focus of RFMO management is on the high seas fisheries but, due to the management needs of highly migratory and straddling fish stocks, can also focus on fisheries operating in Exclusive Economic Zone (EEZ) waters with coastal state agreement.

Tuna RFMOs

The RFMOs are open to countries in the region (coastal states) and other countries with interests in the fisheries concerned. For example, members of the IOTC include the European Union and Japan – both outside the Indian Ocean area but with tuna fishing fleets operating in the region.

Tuna RFMOs have management powers to set limits to catch and fishing effort, agree technical measures and control obligations for tuna and associated species (i.e. fish and non-fish bycatch, or accidental catch of non-target species). The individual countries making up each RFMO implement these management measures separately.


There are five tuna RFMOs:
  • IOTC – Indian Ocean Tuna Commission
  • WCPFC – Western and Central Pacific Fisheries Commission
  • IATTC – Inter-American Tropical Tuna Commission
  • ICCAT – International Commission for the Conservation of Atlantic Tunas
  • CCSBT – Commission for the Conservation of Southern Bluefin Tuna

One, the Commission for the Conservation of Southern Bluefin (CCSBT), focuses on one species (southern bluefin tuna) while the others consider multiple species.