GLOSSARY 6 October, 2000 - ICCAT · GLOSSARY of Fishery Terms This annotated Glossary defines some of the terms frequently found in Executive Summary Reports of the International

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GLOSSARYof Fishery Terms

This annotated Glossary defines some of the terms frequently found in Executive Summary Reportsof the International Commission for the Conservation of Atlantic Tunas´ Standing Committee onResearch and Statistics (SCRS). The definitions are intended for the general public. However,references are also provided for those readers seeking more detailed information on some of themore technical terms.

This Glossary is in draft form and should be considered as tentative until the SCRS finalizes it.

Please provide comments/suggestions to: Victor Restrepo ([email protected])ICCATCorazón de María, 8-6o

28002 Madrid, Spain

AAbundance IndexIndice d´abondanceIndice de abundancia

A quantitative measure of fish density or abun-dance, usually as a time series. An abundance index canbe specific to an area or to a segment of the population(e.g., large fish), or it can refer to abundance stock-wide;the index can reflect abundance in numbers or in weight(biomass). Most abundance indices currently used bythe SCRS are based on standardized CPUE data, al-though fishery-independent abundance indices based onscientific surveys have also been used. Typically, abun-dance indices are in relative units (as opposed to mea-suring absolute abundance), and simply indicate rela-tive changes in abundance over time.

ADAPTADAPTADAPT

A stock assessment program based on VPA andtuning of abundance indices. The population model isage-structured. (Geromont and Butterworth 1997; Powersand Restrepo 1992)

Age at First CaptureAge de première captureEdad de primera captura

See age of recruitment.

Age CompositionStructure démographiqueComposición por edad

The proportion of fish of different ages in the stockor in the catch.

Age-Length KeyClef d´identification âge-longeurClave edad-talla

One approach used to assign ages to fish, givenlength measurements. For example, age-length keys canbe used to convert catch-at-size data into catch-at-agedata. The keys specify the probability that fish of a givensize belong to one of several age groups. Age-lengthkeys need to be constructed from (annual) samples oflength/age data, which have proved to be very difficultfor tunas. As a result, the method of cohort-slicing isused more frequently by the SCRS. (Hoenig et al. 1994)

Age of MaturityAge de maturitéEdad de madurez

The age when 50% of the fish of a given sex areconsidered to be reproductively mature.

Age of RecruitmentAge de recrutementEdad de reclutamiento

The age when fish are considered to be recruitedto the fishery. In stock assessments, this is usually theyoungest age group considered in the analyses, typicallyage 0 or 1.

Age-slicingDécoupage des âgesCorte de edad

See Cohort Slicing.

Albacore (Thunnus alalunga)GermonAtún blanco

A temperate tuna species widely distributedthroughout the Atlantic Ocean and Mediterranean Sea.For assessment purposes, three three stocks are assumed:northern and southern Atlantic stocks (separated at 5ºN)and a Mediterranean stock. Spawning occurs in subtropi-

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cal western areas of both hemispheres and throughoutthe Mediterranean during austral and boreal spring-sum-mer. Until the age of maturity (about 5 years) they aremainly found in surface waters, where they are targetedby surface gears. Some adult albacore are also caughtusing surface gears but, as a result of their deeper distri-bution, they are mainly caught using longlines. Youngalbacore are also caught by longline in temperate wa-ters.

AllocationAllocationAsignación

The partitioning of fishery controls or fishing rightsamong participating entities or operating units. For ex-ample, the allocation of the TAC into country-specificquotas.

Archival TagMarque-archiveMarca-archivo

A type of tag that stores information in a micro-chip. Archival tags are useful to learn about the biologyof fish because they can store variables such as internal(body) and external temperature, pressure (to measuredepth), and light levels (to infer geographic position)for several years.

ArtisanalArtisanalArtesanal

Refers to catch or effort that is neither industrialnor recreational in nature, and which is generated usingsimple fishing methods.

ASPICASPICASPIC

A stock assessment program based on Schaefer´sform of the production model, with non-equilibrium tun-ing of biomass-based abundance indices. The popula-tion model is in lumped biomass. (Prager 1992)

ASPMASPMASPM

A stock assessment program based on a determin-istic form of a stock-recruitment relationship, with non-equilibrium tuning of abundance indices. The popula-tion model is an age-structured production model. (Puntet al. 1992; Restrepo and Legault 1998)

Asymptotic Length (L�

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The maximum size that fish of a given speciescould reach on average if they lived forever. Sometimesit is mistaken for the largest observed size for the spe-cies.

AvailabilityDisponibilitéDisponibilidad

Refers to the distribution of fish of different agesor sizes relative to the distribution of the fishery.

BBase CaseCas de baseCaso base

Pertains to the stock assessment (model and re-sults) that the SCRS uses as the basis to formulate man-agement advice.

BayesianBayésienBayesiano

A formal statistical approach in which expertknowledge or beliefs are analyzed together with data.Bayesian methods make explicit use of probability forquantifying uncertainty. Bayesian methods are particu-larly useful for making decision analyses. (Gelman et al.1995; Porch 1999a; Walters and Ludwig 1994)

BETYPBETYPBETYP

Bigeye Tuna Year Program. A special researchprogram coordinated by ICCAT that aims to augmentscientific understanding of the population dynamics ofbigeye tuna in the Atlantic Ocean, primarily through tag-ging.

Beverton-Holt (stock-recruitment model)Beverton-Holt (modéle stock-recrutement)Beverton-Holt (modelo de stock-reclutamiento)

A particular stock-recruitment formulation inwhich recruitment reaches an asymptote as stock sizebecomes very large.

BiasBiaisSesgo

A systematic difference between the expectedvalue of a statistical estimate, and the quantity it esti-mates.

Bigeye (Thunnus obesus)Thon obèsePatudo

A widely-distributed species of tuna, ranging be-tween 50o N and 45o S. This species dwells in deeperwater than other tunas and shows extensive verticalmovements. Spawning occurs in tropical waters whenthe environment is favorable. From the spawning areabigeye migrate into temperate waters as they grow. Youngfish form schools mostly mixed with other tunas such asyellowfin and skipjack. These schools are often associ-ated with drifting objects, whale shark and sea mounts.This association weakens as they grow larger. Circum-

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stantial evidence suggests a single Atlantic-wide singlestock.

Biological Reference Point (BRP)Point de référence biologiquePunto biológico de referencia

A benchmark against which the abundance of thestock or the fishing mortality rate can be measured inorder to determine its status. These reference points canbe Limits or Targets, depending on their intended us-age. (Caddy and Mahon 1995; Gabriel and Mace 1999;Sissenwine and Shepherd 1987)

BiomassBiomasseBiomasa

Biomass refers to the abundance of the stock inunits of weight. Sometimes, “biomass” refers to onlyone part of the stock (spawning biomass, exploitablebiomass) but this distinction is not always made.

Biomass at MSYBiomasse de PMEBiomasa en RMS

A biological reference point. It is the long-termaverage biomass value expected if fishing at FMSY. Thetext of the International Convention for the Conserva-tion of Atlantic Tunas states that ICCAT is responsiblefor “studying and appraising information concerningmeasures and methods to ensure maintenance of thepopulations of tuna and tuna-like fishes in the Conven-tion area at levels which will permit the maximum sus-tainable catch and which will ensure the effective ex-ploitation of these fishes in a manner consistent withthis catch” (Article IV, paragraph 2.b). (Caddy and Mahon1995)

Bluefin (Thunnus thynnus thynnus)Thon rougeAtún rojo

A temperate tuna distributed throughout the northAtlantic. For assessment purposes, two stocks are as-sumed, although some mixing is known to occur: West-ern and eastern (including the mediterranean) Atlantic.Atlantic bluefin can grow to over 300 cm and reach morethan 650 kg and can live for over 20 years. In the west-ern Atlantic, bluefin generally reach a larger maximumsize, and mature later than eastern bluefin. Spawningoccurs from April to June in the Gulf of Mexico and theFlorida Straits, and from May to July around the BalearicIslands, Tyrrhenian Sea, and central Mediterranean.Large bluefin are adapted for migration to colder wa-ters.

Blue marlin (Makaira nigricans)Makaire bleuAguja azul

A species of billfish found throughout tropical andtemperate waters of the Atlantic and adjacent seas, rang-ing from Canada to Argentina on the west, and from the

Azores to South Africa on the east. A single Atlantic-wide stock is assumed for assessment. Migratory pat-terns can be trans-Atlantic or trans-Equatorial. The spe-cies is considered to be rare and solitary compared toschooling tunas. Spawning occurs in tropical and sub-tropical waters in the summer and fall. Adults are foundpredominately in the open ocean near the surface andare caught most frequently as a by-catch by the offshorelongline fisheries which target tropical or temperate tu-nas using shallow deployment of gear. Significant by-catch landings are also made by offshore longline fish-eries that target swordfish, particularly in the West At-lantic Ocean.

BootstrapBootstrap (processus itératif type bootstrap)Bootstrap (muestreo repetitivo)

A statistical methodology used to quantify theuncertainty associated with estimates obtained from amodel. The bootstrap is often based on Monte Carloresampling of residuals from the initial model fit. (Efronand Tibshirani 1991; Porch 1999b)

By-catchPrise accessoireCaptura secundaria

Catch of species other than the intended target spe-cies in a fishing operation. Bycatch can either be dis-carded or landed. (Alverson et al. 1994)

CCalibrationCalibrageCalibración

See Tuning.

Carrying CapacityCapacité de pêcheCapacidad (del stock, del barco)

(1) Virgin biomass. (2) Refers to the holding ca-pacity of a fishing vessel.

Catch (C)PriseCaptura

The total number of fish caught by fishing opera-tions (sometimes “catch” is used to denote the weight offish caught). Catch should pertain to all fish killed bythe act of fishing, not just those fish that are landed.Catches are reported to ICCAT as part of the “Task I”data.

Catch at Age (CAA)Prise par âgeCaptura por edad

The estimated number of fish caught, tabulatedby fish age and year of capture (and by other strata suchas gear or nation). CAA is estimated on the basis ofCAS, using age-length keys or cohort slicing.

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Catch at Size (CAS)Prise par tailleCaptura por talla

The estimated number of fish caught, tabulatedby size class and by other strata such as gear, nation andquarter. For any given species, CAS should include allfish killed by the act of fishing, not just those fish thatare landed.

Catchability (q)CapturabilitéCapturabilidad

The fraction of the stock which is caught by a stan-dardized (effective) unit of effort. It is also used as theconstant of proportionality that relates effective effortto fishing mortality (q x f = F) or as the constant of pro-portionality that relates an index of abundance to abso-lute stock size (I = q x N). Catchability is affected byfish availability. Thus, specific climatic conditions mayresult increased or decreased availability of the fish. Thiswould lead to increased (decreased) catchability and,thus, increased (decreased) fishing mortality rate withthe same fishing effort.

Catch CurveCourbe de captureCurva de captura

A graph showing the logarithm of catch in num-ber of fish, plotted against fish age. Assuming equilib-rium conditions, the descending limb of a catch curvecan be used to estimate total mortality.

CATCHEMCATCHEMCATCHEM

A stock assessment program based on separableprojections and tuning of abundance indices. The popu-lation model can be age/length-structured. (Porch 1996)

Catch per Unit Effort (CPUE)Capture par unité d´effortCaptura por unidad de esfuerzo

The amount of catch that is taken per unit of fish-ing effort (e.g., number of fish per longline hook-months). Nominal CPUE is often used as a measure ofthe economic efficiency of a type of gear. StandardizedCPUE is normally used as an abundance index for “tun-ing” or fitting assessment models.

Catch RateTaux de captureTasa de captura

See Ctach per Unit Effort.

CohortCohorteCohorte

The fish born in the same time period, usually ayear. For instance, the 1987 cohort would refer to fishthat are age 0 in 1987, age 1 in 1988, and so on.

Cohort analysis (CA)Analyse des cohortesAnálisis de cohorte

A simplified VPA algorithm based on an approxi-mation that assumes that, in a given time period, all fish-ing takes place instantaneously in the middle of the timeperiod. (Pope 1974)

Cohort SlicingDécoupage des cohortesSeparación de cohorte

One approach used frequently to assign ages tofish, given length measurements. For example, cohortslicing is used to convert catch-at-size data into catch-at-age data before the application of age-structured as-sessment models. Cohort slicing assumes that there is aone-to-one correspondence between length and age (i.e.the approach ignores individual variability in growth).

CommercialCommercialComercial

Refers to catch or effort that is commercial in na-ture, typically using industrial-type vessels and gears.

ConditioningConditionnéCondicionado

Statistical estimates are often based on the assump-tion that some of the inputs are known exactly, a prac-tice known as conditioning. For example, a VPA is con-ditioned on the catch at age.

Confidence limitsLimites de confianceLímites de confianza

A statistical measure of uncertainty, providing thelower and upper bounds within which a parameter fallswith a given probability. Example: the 80% confidencelimits for SSB are the low and high values within whichSSB lies with 80% certainty.

ControlsContrôlesControles

Refers to the various controls (measures) that man-agers can impose to regulate fishing. Controls are usu-ally classified as effort controls or catch controls, de-pending on what they intend to regulate. (Gulland 1974;Pallarés and Suzuki 1998)

Conversion FactorsFacteurs de conversionFactores de conversión

Multipliers applied to convert landings into Nomi-nal Catches. These factors vary with the species involvedand with the dressing of the fish (e.g. fresh, frozen, gut-ted, etc.,.). They could also vary by country and overtime.

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Cryptic BiomassBiomasse cryptiqueBiomasa críptica

The term is sometimes used to describe the frac-tion of the stock that is unavailable to the fisheries (seeAvailability). (Laloë 1989; Fonteneau et al. 1998)

CV (Coefficient of variation)CV (coefficient de variation)CV (coeficiente de variación)

The standard error of a statistic, divided by itsestimate. The C.V. gives an idea of the precision of anestimate, independent of its magnitude.

DDecision analysisAnalyse de prise de décisionAnálisis de decisión

A formal analysis to aid decision-making in theface of uncertainty. A decision analysis usually evalu-ates the expected outcomes (e.g., average catch, con-stancy of catch, probability of rebuilding to a given bio-mass target, etc.,) of alternative management controls.A decision analysis can also address management con-sequences under different plausible assumptions aboutthe status of the stock. (Kim 1992)

Delta MethodMéthode DeltaMétodo Delta

Also known as the Taylor Series method, the Deltamethod is a statistical procedure used to quantify theuncertainty associated with estimates obtained from amodel. More specifically, the Delta method quantifieshow the variance propagates from the parameters thatare estimated directly by the statistical model (e.g., cur-rent SSB), and those parameters that are derived fromthe application of mathematical formulations (e.g. fu-ture SSB based on model projections). (Seber 1982)

DeterministicDéterministeDeterminista

A process that has no stochastic (random) compo-nents. For example, the population model of some stockassessment methods assumes that population growth dueto recruitment follows a deterministic formulation.

DepletedSurexploitéMermado

See Overfished.

DiscardsRejetsDescartes

Refers to part of the catch that is thrown over-board at sea. Discards may be released either dead oralive. Scientists generally estimate the dead discards aspart of the total catch. Estimates of discards can be made

in a variety of ways, including samples from observersand logbook records. Fish (or parts of fish) can be dis-carded for a variety of reasons such as having physicaldamage, being a non-target species for the trip, and com-pliance with management regulations like minimum sizelimits or quotas.

DNAADNADN

Deoxyribonucleic acid, the molecular basis of he-redity in many organisms. Genetic DNA analyses cansometimes provide information on the structure of popu-lations and thus be used to define stocks on a biologicalbasis.

Dressed Weight (DWT)Poids manipuléPeso eviscerado

A type of weight measurement frequently madefor ICCAT species (primarily billfishes), particularlyafter unloading, where the gills, guts, head and fins havebeen removed and discarded at sea. ICCAT catch data(yield) are in Round Weight, so conversion factors areused for each species when measurements are made indressed weight.

Dynamic Pool ModelModèle dynamique d´aggrégation“Dynamic pool model”

The term is used to describe yield-per-recruit typesof models.

EEEZZEEZEE

Exclusive Economic Zone (defined in the Law ofthe Sea Convention).

Effective Effort (f)Effort effectifEsfuerzo efectivo

Measures of fishing effort such as hooks per dayof fishing that have been standardized so that the mea-sure is proportional to the fishing mortality rate that thegear(s) impose on the stock of fish. Controls purportedto limit effective effort imply that the fishing mortalityrate is to be limited.

Effort (Fishing Effort, f)Effort (effort de pêche)Esfuerzo (esfuerzo de pesca)

A measure of the intensity of fishing operations.How Effort is defined depends on the type of fishery(gear) and often on the type of information available.For longline fisheries, effort is usually defined in unitsof number of hooks or in hook-hours. For purse-seinefisheries, effort is often defined as boat-days (time fish-ing plus search time). Scientists should aim to define

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effort in a way that facilitates effort standardization.

EFL (Eye-fork length)EFL (longueur cavité oculaire-fourche)EFL (longitud ojo-horquilla)

A measurement used frequently for ICCAT bill-fish species: Projected straight or curved-body distancebetween the posterior edge of the eye orbit and the forkof the tail.

EquilibriumConditions d´équilibreEquilibrio

A situation that arises when the fishing mortality,exploitation pattern and other fishery or stock charac-teristics (growth, natural mortality, recruitment) do notchange from year to year. Many yield per recruit analy-ses assume equilibrium. That is, equilibrium yield perrecruit that is computed for a given fishing mortality canbe achieved if that fishing mortality is held constant formany years (as many years as there are age classes inthe fishery); equilibrium yield per recruit values com-puted for a new level of fishing mortality or a change inselectivity would not be expected to reach equilibriumuntil several years from the time of implementation (seeTransitional). Other types of stock assessments such asvariants of stock production models or catch curves alsoassume equilibrium. Their non-equilibrium variants aimto better explain the dynamics of the observed datathrough time. (Hilborn and Walters 1992)

Equilibrium Yield CurveCourbe de production équilibréeCurva de rendimiento en equilibrio

A function that describes the long-term yield whichwould be obtained at different levels of fishing mortal-ity. At its highest point, the equilibrium yield is theMaximum Sustainable Yield (MSY) and the associatedfishing mortality rate is FMSY. (Restrepo et al. 1994)

Excess CapacityCapacité excédentaireExceso de capacidad

In the short-term, it is the fishing capacity overand above that which is needed to extract the TAC fromthe stock. In the long-term, it is the fishing capacityover and above that which is needed to achieve the man-agement objectives (e.g. to generate a fishing mortalityequal to FMSY).

Exploitable BiomassBiomasse exploitableBiomasa explotable

Refers to that portion of a stock´s biomass that isavailable to the fishing gear.

Exploitation PatternMode d´exploitationPerfil de explotación

The distribution of fishing mortality over the agecomposition of the fish, determined by the type of fish-

ing gear and spatial and seasonal distribution of fishing,and by the growth and migration of the fish. In otherwords, it is the combined effect of gear selectivity andfish availability. The pattern can be changed by modifi-cations to fishing gear; for example, by increasing meshor hook size or by changing the ratio of harvest by gearsexploiting the fish (e.g., gill net, trawl, hook and line).The pattern can also change due to changes in fishingpractices such as avoidance of areas where juvenilesreside.

Exploitation RateTaux d´exploitationTasa de explotación

The proportion of a population at the beginningof a given time period that is caught during that timeperiod (usually expressed on a yearly basis). For ex-ample, if 220,000 fish were caught during the year froma population of 1 million fish alive at the beginning ofthe year, the annual exploitation rate would be 0.22.

Exploitation RatioRatio de l´exploitationRatio de explotación

The ratio of fish caught to total mortality (= F/Z).

FF0.1F0.1

F0.1

A biological reference point. It is the fishing mor-tality rate at which the increase in equilibrium yield perrecruit in weight for an increase in a unit of effort is10% of the yield per recruit produced by the first unit ofeffort on the unexploited stock (i.e., the slope of the yieldper recruit curve for the F0.1 rate is only 1/10th of theslope of the yield per recruit curve at its origin). [Note:F0.1 is sometimes computed from equilibrium yieldcurves]. Originally, F0.1 was intended as an economicreference point, measuring where additional investmentinto effective fishing effort would only produce a 10%marginal gain in yield per recruit. It later evolved into aconservative reference point for yield optimization be-cause F0.1 results in almost as much yield per recruit asFmax does, but at lower levels of fishing mortality. (Caddyand Mahon 1995)

FmaxFmax

Fmax

A biological reference point. It is the fishing mor-tality rate that maximizes equilibrium yield per recruit.Fmax is the F level that defines growth overfishing. Ingeneral, Fmax is different than FMSY (the F that maximizessustainable yield), and is usually higher than FMSY, de-pending on the stock-recruitment relationship. By defi-nition, Fmax is always higher than F0.1. (Caddy and Mahon1995)

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FmedFmed

Fmed

A biological reference point. It is the fishing mor-tality rate corresponding to an equilibrium SPR equal tothe inverse of the median observed survival ratio (ratioof recruits to parental spawning biomass). That is, astock exploited indefinitely at Fmed should be able to re-place itself with an abundance close to the observed his-torical median. In consequence, the degree of conser-vatism implied by Fmed depends largely on whether the“observed” (i.e. assessed) history of the stock corre-sponds to an overfished state or to a lightly-exploitedstate. (Caddy and Mahon 1995; Sissenwine and Shepherd1987)

FMSYFPME

FPME

A biological reference point. It is the fishing mor-tality rate which, if applied constantly, would result inMaximum Sustainable Yield (MSY). FMSY is the im-plicit fishing mortality target of the International Con-vention for the Conservation of Atlantic Tunas (seeBMSY). FMSY can be estimated in two ways: (1) Fromsimple (biomass-aggregated) production models (e.g.,ASPIC, PRODFIT); (2) from age-structured models thatinclude a stock-recruitment relationship (e.g., ASPM).(Caddy and Mahon 1995)

fopt (fMSY)fopt

fopt

A biological reference point. It is the effectivefishing effort corresponding to FMSY. fopt is often reportedas one of the main outputs of production models. (Fox1975)

F-ratioF-ratioRatio de F

The ratio of fishing mortality on the oldest agegroup to the fishing mortality of the preceding age group.Annual F-ratios are estimable parameters in many tunedVPA assessments.

F�

(Fcrash)F

� (Fcrash)

F� (Fcrash)

A biological reference point. It is the fishing mor-tality rate corresponding to an equilibrium SPR equal tothe inverse of the survival ratio at the origin of the stock-recruitment relationship. A stock exploited indefinitelyat F

�

is expected to collapse sooner or later (hence theterm “Fcrash”) due to recruitment failure. F

�

is usuallycomputed from age-structured data based on a fit to thestock-recruitment observations. F

�

can also be repre-sented by the highest fishing mortality value at whichyield becomes 0 in an equilibrium yield curve. (Gabrieland Mace 1999)

FX% (FX%SPR)FX%

FX%

A family of biological reference points. FX% de-notes the fishing mortality that will reduce the equilib-rium spawning potential per recruit to X% of what itwould be without any fishing (or, equivalently, it is theF that results in X% equilibrium spawning potential ra-tio). Reference points of this kind are often used as prox-ies to other biological reference points that require moreinformation about the relationship between stock andrecruitment. For example, based on simulation studiesfor groundfish stocks, F20% has been recommended as adefault proxy for recruitment overfishing and F35% as aproxy for FMSY. The performance of specific FX% poli-cies for ICCAT stocks has not been studied thoroughly.(Caddy and Mahon 1995)

FAD (Fish Aggregating Device)DCP (Dispositif de concentration du poisson)DCP (dispositivo de concentración de peces)

Artificial or natural objects placed on the surfacethat attract several species underneath, thus increasingtheir catchability. (Kwei and Bannerman 1993; Pallarés etal. 1998)

FecundityFéconditéFecundidad

The number of eggs produced on average by afemale of a given size/age. Fecundity information isoften used to compute spawning potential.

FinningPrélèvement des aileronsCorte de aletas

The practice of removing fins and discarding thecarcass, usually pertaining to sharks.

FISFISFIS

Refers to the joint France-Cote d´Ivoire-Senegalfleet that targets tropical tunas off Africa.

Fishery-IndependentIndépendant de la pêcheIndependiente de la pesquería

Refers to statistics about the stock that are col-lected independently of the fisheries, e.g. through scien-tific surveys. Most ICCAT data are fishery-dependent.

Fishing CapacityCapacité de pêcheCapacidad de pesca

Usually refers to the size and characteristics ofindividual fishing vessels (see Carrying Capacity).

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Fishing GearsEngins de pêcheArtes de pesca

The equipment used for fishing. Some of the mostcommon fishing gears for tunas and tuna-like fish arebaitboat, gillnet, handline, harpoon, troll, haul seine,longline, widwater trawl, purse seine, rod-and-reel, trap,and trawler (see gear codes towards the end of the Glos-sary). Each of these can have multiple configurations.

Fishing Mortality Rate (F)Taux de mortalité par pêcheTasa de mortalidad por pesca

The part of the total mortality rate that is due tofishing. Fishing mortality is usually expressed as an in-stantaneous rate, as discussed under Mortality Rate, andcan range from 0 per year (for no fishing) to high valuessuch as 1.0 or more per year. Fishing mortality shouldreflect all deaths in the stock that are due to fishing, notjust those fish that are actually landed. It is commonpractice to refer to F as a scalar value but it would bemore appropriate to refer to it as a vector. That is, it isimportant to consider how F is distributed among agegroups (i.e. what the exploitation pattern is). For in-stance, and F value of 0.5 for a stock exploited by purseseines that target small fish would have very differentconsequences than an F=0.5 for the same stock exploitedby longlines targeting large fish.

Fishing PatternMode de PêchePatrón de explotación

See Exploitation Pattern. Sometimes the term isalso used in reference to the way in which fishing opera-tions are conducted.

Fishing PowerPuissance de pêchePotencia pesquera

Refers to the efficiency of a fishing unit, usually avessel, in capturing fish. The fishing power of individualfishing units can change over time (typically increas-ing) in response to technological developments in fish-ing gear, engines or sonar equipment, and adjustmentsto fishing practices.

FittingAjustementAjuste

See Tuning.

FL (fork length)FL (longueur à la fourche)FL (longitud a la horquilla)

A measurement used frequently for tunas: Pro-jected straight distance between the tip of the fish andthe fork of the tail.

FlagPavillonBandera

Refers to the State in which a boat is registered.

Flag of Convenience (FOC)Pavillon de complaisanceBandera de conveniencia

The term pertains to cases when a boat is regis-tered in a different State than that of ownership, for what-ever reasons of convenience.

Fleet StatisticsStatistiques sur les flottillesEstadísticas de flota

Data used to monitor the basic makeup of fishingfleets. Some fleet statistics are important for measuringFishing Capacity. ICCAT collects basic fleet statisticsfrom all countries/entities fishing for tunas in the Atlan-tic under “Task I” data.

Floating ObjectObjet flottantObjetos flotantes

See FAD.

Fox ModelModèle de FoxModelo Fox

A specific form (the “logistic” shape) of produc-tion model. Traditionally, the Fox model has been ap-plied to catch and effort data for many stocks of tropicaltunas. (Fox 1974, 1975)

Fully ExploitedPleinement exploitéPlena explotación

The term means that the stock is not being over-exploited nor underexploited. This can be interpretedin an equilibrium yield sense as fishing at FMSY, or in ayield-per recruit sense as fishing at Fmax.

GGeneralized Additive Model (GAM)Modèle additif généraliséModelo generalizado aditivo

A statistical procedure similar to a GeneralizedLinear Model, excpet that the response variable (e.g.CPUE) can be modeled as a nonlinear function of thedependent variables (e.g. time, latitude, etc.).

Generalized Linear Model (GLM)Modèle linéaire généraliséModelo linear generalizado

A statistical procedure similar to an Analysis ofVariance or a Multiple Regression that is used to esti-mate the magnitude of the effects of different factors ona variable of interest. GLMs are the tool of choice forstandardizing CPUE data in order to obtain indices ofabundance. In such applications, the variable of inter-

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est is CPUE and the factors are Year and perhaps otherssuch as area, gear configuration, etc.; the standardizedabundance index of annual abundance would then begiven by the parameters associated with the factor Year.(Brown and Porch 1997; Cooke and Lankester 1996;McCullagh and Nelder 1989)

GENPRODGENPRODGENPROD

A stock assessment computer program based onthe “generalized” form of the production model, withnon-equilibrium tuning of biomass-based abundance in-dices. The population model is in lumped biomass. (Pellaand Tomlinson 1969)

Gilled and Gutted WeightEviscéré et sans branchiesPeso eviscerado y sin agallas

A type of weight measurement frequently madefor ICCAT species (yellowfin, bigeye and bluefin tu-nas), particularly after unloading, where the gills andguts (and sometimes the heads as well) have been re-moved and discarded at sea. ICCAT catch data (yield)are in Round Weight, so conversion factors are used foreach species when measurements are made in gilled andgutted weight.

Global ModelModèle globalModelo global

The terms is sometimes used to describe produc-tion models.

Growth OverfishingSurpêche de croissanceSobrepesca de crecimiento

Growth overfishing occurs when the fishing mor-tality rate is above Fmax. This means that individual fishare caught before they have a chance to reach their maxi-mum growth potential. (Gulland 1974)

Growth RateTaux de croissanceTasa de crecimiento

(1) Intrinsic growth rate: A value that quantifieshow much a population can grow between successivetime periods. The intrinsic growth rate is often estimatedwith production models and plays an important role inevaluating the sustainability of different harvest levels.(2) Individual growth rate: A value that quantifies howfast the average individual in the population grows insize or in weight.

GRTTJBTRB

Gross Registered Tonnage, a measure of a vessel´svolume.

GTTBTB

Gross tonnage (will replace GRT in general).

HHarvest Control RuleRéglementation de contôle des capturesNorma de control de captura

Describes a variable over which management hassome direct control as a function of some indicator ofstock status. For example, a harvest control rule candescribe a plan for how to adjust fishing mortality lev-els, depending on the abundance of a stock. Constantcatch and constant fishing mortality are two types ofsimple harvest control rules.

IIntegrated AnalysisAnalyse intégréeAnálisis integrado

Refers to stock assessment methodologies that at-tempt to integrate multiple sources of data into a singleestimation framework. For example, an integrated as-sessment can attempt to fit the following observationsbased on model predictions: Total landings by fleet, sizesamples of landings, discard estimates, size samples ofdiscards, standardized CPUE by fleet, fishery-indepen-dent surveys, and tagging records on movement, growthand recoveries. (Fournier et al. 1998; Porch 1996)

ITQ (Individual Transferable Quota)ITQ (Quota individuel transférable)ITQ (Cuota individual transferible)

A type of quota management system which typi-cally entails the allocation of a part of the TAC to indi-vidual fishermen or vessel owners. The quota, once dis-tributed, can be sold to others. (NRC 1999)

IUUIUUIUU

Illegal, Unregulated and Unreported fishing ves-sels.

LLandingsDébarquementsDesembarques

The part of the catch that is landed.

Laurec-ShepherdLaurec-ShepherdLaurec-Shepherd

A stock assessment method based on VPA and Adhoc tuning of abundance indices. The population modelis age-structured.

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Least SquaresMoindres carrésCuadrados mínimos

A statistical criterion for the estimation of param-eters in regression. Least squares means that the methodaims to minimize the sum of squared differences betweenthe observations and the predictions from a model. Forexample, VPA tuning often involves finding the estimatesof abundance and mortality rates that minimize the sumof squared differences between standardized CPUE andpredicted abundance from the VPA.

Life HistoryEvolution du cycle vitalCiclo vital

A summary of the entire life cycle of the specieswhich describes how the average individual is born,grows, reproduces and dies.

LifespanLongévitéDuración de vida

A species´ life expectancy in the absence of a fish-ery.

Limit Reference PointPoints limites de référencePunto de referencia límite

A benchmark that should not be exceeded withany significant probability according to a given set ofmanagement objectives. According to the UNIA, FMSYshould be a limit reference point. ICCAT´s objectivesdo not define limit reference points explicitly, althoughFMSY is the implied target. (Caddy and Mahon 1995)

LJFL (Lower jaw-fork length)LJFL (Longueur maxillaire inférieur-fourche)LJFL (Longitud mandíbula inferior-horquilla)

A measurement used frequently for billfishes spe-cies: Projected straight distance between the tip of thelower jaw and the fork of the tail.

LOALOA (Longeur hors-tout)LOA (Eslora total)

“Length overall”, a measure of the size of a fish-ing vessel.

LogbookCarnet de pêcheCuaderno de pesca

An official record of a fishing vessel´s fishingoperations (including location and time of catches, gearconfiguration, nominal effort used, size samples, etc.).Loogbooks are mandatory in some States and are thebasis of much of ICCAT´s “Task II” data.

MManagement StrategyStratégie de gestionEstrategia de ordenación

Refers to the management system as a whole (in-cluding support activities such as stock assessment)geared towards the achievement of specific managementobjectives. A management strategy can be defined morenarrowly as the combination of a particular data collec-tion system, a particular stock assessment technique anda particular harvest control rule and its implementation.In such a way, alternative management strategies can becompared against each other via simulation.

MaturityMaturitéMadurez

Refers to the ability, on average, of fish of a givenage/size to reproduce. Maturity information, in the formof percent mature by age/size, is often used to computespawning potential.

Maximum Economic Yield (MEY)Production économique maximaleRendimiento económico máximo

Conceptually similar to Maximum SustainableYield, except that the objective is to maximize longtermprofits.

Maximum LikelihoodProbabilité maximaleMáxima verosimilitud

A statistical criterion for the estimation of param-eters in models. The method aims to maximize the like-lihood (probability) of having collected the observeddata, given predictions from a model. For example, VPAtuning often involves finding the estimates of abundanceand mortality rates that maximize the likelihood for theobserved standardized CPUE. Under some conditions,the methods of Maximum Likelihood and Least Squaresgive similar results. (Freund and Walpole 1987)

Maximum Sustainable Yield (MSY)Production maximale soutenable (PME)Rendimiento máximo sostenible (RMS)

The largest average yield (catch) that can be takenin the long-term from a stock, which corresponds to theyield expected from fishing at FMSY. ICCAT´soverarching objective is to make sure that stocks will bemaintained at levels that permit harvest levels of MSY(see BMSY).

MicroconstituentMicroélémentMicroelemento

Refers to the elemental makeup of bone structures.Like DNA, microconstituents can sometimes be used toinfer something about the structure of populations.

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Minimum SizeTaille minimaleTalla mínima

A control available to managers, intended to mini-mize the catches of small fish. Such a control is oftendecided upon based on yield per recruit considerationslike avoiding growth overfishing. That is, minimum sizeregulations aim to alter the exploitation pattern so thatyoung fish are given a better chance to grow before be-ing vulnerable to fishing.

ModelModèleModelo

A conceptual and simplified idea of how the “realworld” works.

Monte CarloMonte CarloMonte Carlo

Monte Carlo simulation is an approach wherebythe inputs that are used for a calculation are re-sampledmany times assuming that the inputs follow known sta-tistical distributions. The Monte Carlo method is usedin many applications such as Bayesian analyses, para-metric bootstraps and stochastic projections. (Manly 1991)

MoratoriumMoratoireMoratoria

A cessation of fishing activities.

Mortality Rate (instantaneous)Taux (instantané) de mortalitéTasa de mortalidad (instantánea)

Conceptually, the easiest way to describe mortal-ity is as a fraction (e.g. 0.3 or 30% of the fish die in ayear). Because fishing and natural mortality happencontinuously throughout the year, it is not straightfor-ward to use these fractions in an additive way. Express-ing these processes as instantaneous rates (i.e. as the frac-tions that die in infinitesimal periods of time) facilitatesthe stock assessment analysis computations on an an-nual basis, even when the catches take place daily. In-stantaneous mortality rates of 0.1, 0.5 and 1.0 are equiva-lent to 10%, 39% and 63% mortality.

MSP (Maximum Spawning Potential)MSP (Potentiel reproducteur maximal)MSP (potencial máximo de desove)

See SPR.

MULTIFAN-CLMULTIFAN-CLMULTIFAN-CL

A stock assessment program based on length-basedseparable models and tuning of abundance indices. Thepopulation model is length/age-structured. (Fournier etal. 1998)

NNAO (North Atlantic Oscillation index)NAO (Indice de l´Oscillation nord-atlantique)NAO (Indice de oscilación del Atlántico norte)

An index of climatic conditions given by the dif-ferences in winter sea level pressures between Lisbon,Portugal, and Stykkisholmar, Iceland. Several studieshave looked for correlations between NAO anomalies(deviations from the mean) and recruitment strength oftunas or swordfish. (Mejuto 1999)

Natural Mortality Rate (M)Taux de mortalité naturelleTasa de mortalidad natural

The part of the total mortality rate that is due tocauses other than fishing (e.g., predation, disease, can-nibalism, and perhaps increasingly, environmental deg-radation such as pollution). These many causes of deathare usually lumped together for convenience, becausethey are difficult to separate quantitatively. Sometimesnatural mortality is confounded with losses of fish fromthe stock due to emigration. M has proven very difficultto estimate, and values are often assumed based on lifehistory characteristics such as longevity. Also, M val-ues are often assumed to remain constant through timeand by age.

NEI (Not Elsewhere Included)NEINEI

Refers to catch statistics that cannot be linked di-rectly to a State or fishing entity, for whatever reason.

NominalNominalNominal

Refers to quantities as they are reported, beforeany analyses or transformations. Nominal catch is thesum of catches that have been reported as round weightor, equivalently, the landings (nominal catches do notinclude such measures as unreported dead discards).Nominal effort pertains to measures of fishing effort orvessel carrying capacity that have not been standard-ized. When catchability changes, e.g., through changesin gear technology, trends in nominal effort can give amisleading picture of trends in exploitation.

Non-equilibriumNon-équilibreNo equilibrio

See Equilibrium.

Numbers at age (N)Nombre à l´âgeNúmeros por edad

The number of fish in each age class in the stockat a particular point in time. Age-structured assessmentmodels aim at estimating these quantities.

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OObserverObservateurObservador

An independent person that collects informationonboard fishing vessels. Observer programs can be usedfor quantifying bycatch and dead discards, collecting tagreturns, etc. (Matsumoto and Miyabe 1999)

OptimumOptimalOptimo

The term is used to mean that the stock is beingexploited in complete harmony with management ob-jectives. Since these objectives can be biological, eco-nomic or social, the term Optimum can have differentimplications in terms of harvest rates.

OtolithOtolitheOtolito

The ear bone of a fish. Otoliths are used for age-ing fish of many species, like rings are used in trees.However, the otoliths of most ICCAT species are noto-riously difficult to extract and read, and thus they arenot used routinely to prepare age-length keys.

OverfishedSurexploitéSobreexplotado

Overfished means that the abundance of the stockis “too low”. In many fisheries fora the term is usedwhen biomass has been estimated to be below a limitbiological reference point that is used as the signpostthat defines an “overfished condition”. ICCAT has notformally defined when a stock is to be categorized asbeing overfished, so usage of the term may not alwaysbe consistent. (Mace 1998)

OverfishingSurpêcheSobrepesca

The term generally means that the fishing mortal-ity being exerted on the stock is “too high”. In manyfisheries fora the term is used when F has been estimatedto be above a limit biological reference point that is usedas the signpost that defines “overfishing”. Usage of theterm is not limited to “growth overfishing” situations; itcan also pertain to recruitment overfishing and to othertypes of overfishing. As with the term Overfished,ICCAT usage of “overfishing” may not always be con-sistent. (Mace 1998)

PParameterParamètreParámetro

A quantity that characterizes a population variable

in a statistical sense. In population dynamics models,parameters such as the rates of growth, mortality andreproduction provide the essential characteristics of thepopulation.

Partial RecruitmentRecrutement partielReclutamiento parcial

See Exploitation Pattern.

PelagicPélagiquePelágico

A species that lives in midwater or close to thesurface. Tunas and tuna-like fishes are generally referredto as “large pelagics”.

PopulationPopulationPoblación

A group of fish of one species which shares com-mon ecological and genetic features. The stocks de-fined for the purposes of stock assessment and manage-ment do not necessarily coincide with self-containedpopulations.

Population DynamicsDynamique des populationsDinámica de poblaciones

In general, refers to the study of fish stock abun-dance and why it changes over time.

Population ModelModèle de populationModelo de poblaciones

A component of a stock assessment model, madeup of formulations that describe how the populationchanges from one time period to the next. The types ofpopulation models used by ICCAT vary, depending onthe species life history and on data availability. Popula-tion models can roughly be classified as age/size struc-tured or biomass-based; deterministic or stochastic; den-sity-dependent or density-independent; spatially-struc-tured or spatially aggregated; equilibrium or non-equi-librium.

Pop-up TagMarques pop-upMarcas pop-up

A tag that detaches itself from the fish after a pre-determined period of time has elapsed since tagging. Af-ter detachment, the tag sends a signal via satellite, pro-viding its position and downloading any other availableinformation (if the pop-up tag is also an archival one).This technology does not rely on the recapturing/report-ing of tagged fish to recover the information. (de Metrioet al. 1999)

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Precautionary ApproachApproche de précautionEnfoque precautorio

“A set of agreed cost-effective measures and ac-tions, including future courses of action, which ensuresprudent foresight, reduces or avoids risk to the resource,the environment, and the people, to the extent possible,taking explicitly into account existing uncertaintiesandthe potential consequences of being wrong" (García 1996)

PRODFITPRODFITPRODFIT

A stock assessment computer program based onthe generalized form of the production model, with equi-librium tuning of biomass-based abundance indices. Thepopulation model is in lumped biomass. The “FoxModel” is one of the optional production functions thatcan be used. (Fox 1975)

Production ModelModèle de productionModelo de producción

A population model that describes, using simplefunctions, how the population biomass changes from yearto year (or, how biomass changes in equilibrium as afunction of fishing mortality). The simplest productionfunctions aggregate all of the biological characteristicsof growth, natural mortality and reproduction into asimple, deterministic model using three or four param-eters. Production models are primarily used in simple-data situations, where total catch and effort data are avail-able but age-structured information are either unavail-able or deemed to be less reliable (although some ver-sions of production models allow the use of age struc-tured data). (Cadima and Pinho 1996)

ProjectionProjectionProyección

A computation of how the stock and fishery willbehave in the future. Projections are made to address“what-if” questions of relevance to management. Short-term (1-4 years) projections are typically used in sup-port of decision-making on quotas. Longer term pro-jections become much more uncertain in terms of abso-lute quantities, because predicted recruitment tends todominate the results and recruitment itself is very diffi-cult to predict. For this reason, long-term projectionsare more useful to evaluate overall management strate-gies than for making detailed decisions.

ProxyIndice approchantAproximación

A substitute for some quantity. Scientists often useproxies for quantities that are not easy to estimate. Forexample, F0.1 or Fx%SPR are sometimes used as proxiesfor FMSY.

PWGPWGGTP

Permanent Working Group for the Improvementof ICCAT Statistics and Conservation Measures.

QQuotaQuotaCuota

A portion of a TAC allocated to a fishery or to anoperating unit, such as a size class of vessels or a coun-try.

RRaisingExtrapolationExtrapolación

A procedure for estimating the total from a sample,by multiplying all the fractions in the sample by a “rais-ing factor” equal to the proportion of the total which thesample represents. For example, the total catch at sizefor a fishery is obtained by raising catch-at-size samplesto the magnitude of the total catches, i.e. by multiplyingthe sampled numbers times the ratio of sample weightto total catch weight (or the ratio of sample numbers tototal numbers).

RebuildingRétablissementRecuperación

Refers to the trajectory of a stock from an over-fished condition to a defined target. For example, a stockmay be rebuilt to the BMSY level.

RecommendationRecommandationRecommendación

A decision made by the Commission, typically ofa regulatory nature, which should be implemented do-mestically by Contracting Parties.

RecreationalSportifDeportivo/a

Refers to catch or effort that is exerted by sports-men.

RecruitmentRecrutementReclutamiento

The amount of fish that first become vulnerableto the fishery each year due to growth and/or migrationinto the fishing area.

Recruitment OverfishingSurpêche de recrutementSobrepesca de reclutamiento

The rate of fishing above which the recruitment to

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the exploitable stock becomes significantly reduced.This is characterized by a greatly reduced spawningstock, a decreasing proportion of older fish in the catch,and generally very low recruitment year after year. Re-cruitment overfishing can lead to stock collapse.

Regime ShiftChangement de régimeCambio de régimen

A (medium- or long-term) shift in environmentalconditions that impacts the productivity of a stock.(Beamish et al. 1999)

Replacement YieldProduction de remplacementRendimiento de reemplazo

The amount of yield in weight that can be removedfrom a population of fish and have that stock neitherincrease nor decline in biomass. When the populationproductivity is high under proper exploitation, then re-placement yield will also be high. Conversely, when thepopulation is underexploited or overexploited, then re-placement yields will be low. In either case, if the ac-tual yield taken is equal to the replacement yield, thenthe biomass will not change from one year to the next.See also surplus production.

ResidualValeur résiduelleResiduo

In statistical models, a residual is the differencebetween an observed quantity and the prediction givenby the model (see Least Squares).

ResilienceRésistanceElasticidad

Refers to the ability of a stock to recover fromoverfishing once fishing mortality rates are lowered.

ResolutionRésolutionResolución

A decision made by the Commission which is notbinding (see Recommendation).

Retrospective PatternMode rétrospectifEsquema retrospectivo

A diagnostic that indicates a potentially seriousbias in a stock assessment. A retrospective pattern indi-cates that, as new years worth of data are added, themodel estimates for the most recent years change sub-stantially and in a systematic fashion. For example, theestimate of F for 1995 is very high when 1995 is the lastyear in the model; as more years are added, the estimatebecomes progressively smaller (or, viceversa, the ten-dency could be one of increasing F with increasing data).(Hiramatsu 1993)

Ricker (stock-recruitment model)Ricker (modèle stock-recrutement)Ricker (modelo de stock-reclutamiento)

A particular stock-recruitment formulation inwhich recruitment is dome-shaped, reaching a maximumat an intermediate level of parental stock size.

RiskRisqueRiesgo

The term is used loosely to mean the probabilityof some undesired event (e.g., the risk of stock collapse).More rigorously, in decision analyses, it means the prob-ability of an undesired event times a quantitative mea-sure of the consequence(s) of the bad event. (Punt et al.1996)

Round WeightPoids vifPeso en vivo

The whole weight of an individual fish, i.e. beforeit is processed (see gilled and gutted). ICCAT Task Idata are in round weight units.

SSafe Biological LimitLimite biologique de sécuritéLímite biológico de seguridad

A Limit reference point, usually the stock biom-ass below which recruitment will decline substantially.

Sailfish (Istiophorus albicans)VoilierPez vela

A billfish distributed around tropical and subtropi-cal waters, with high concentrations in coastal watersbut also found in oceanic waters. Eastern and westernstocks are assumed for assessment. Sailfish are the mostcommon Atlantic istiophorid and are can occur in smallgroups of a dozen or more fishs. They are found pre-dominately near the surface and are caught most fre-quently as a bycatch of the offshore longline fisheries.Spawning occurs in tropical and subtropical waters fromthe spring through summer.

Schaefer ModelModèle de SchaeferModelo Schaefer

A specific form (the “parabolic” shape) of aggre-gated biomass stock production model. In the Schaefermodel, BMSY is at one-half of the carrying capacity.(Prager 1992; Schaefer 1994)

SchoolBanc (matte)Cardumen

A group of fish swimming together. Schools areoften formed by fish of the same species and age or size.Some tuna fishing gears are designed to target schools.

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Scientific SurveyCampagne d´échantillonnage scientifiqueEncuesta científica

A fishery-independent survey that is designed sci-entifically to achieve a given objective. For instance, ascientific survey can aim to produce an abundance in-dex that is not affected by changes in catchability due tochanges in gear technology.

SCRSSCRSSCRS

Standing Committee on Research and Statistics(ICCAT).

Search timeTemps de rechercheTiempo de búsqueda

Refers to the time that a fishing vessel spends look-ing for fish schools. For purse seine operations, searchtime is often calculated as the time at sea minus the du-ration of the set.

SelectivitySélectivitéSelectividad

The relative vulnerability of different age or sizeclasses to the fishing gear. Selectivity and exploitationpattern are often used interchangeably.

Sensitivity AnalysisAnalyse de la sensibilitéAnálisis de sensibilidad

The process of testing the sensitivity of input pa-rameters on model results. For example, an estimationprocedure such as VPA might be used to determine thefishing mortality rates over several years. The resultsmight be conditioned on an assumed annual naturalmortality rate (M) of 0.2. The Sensitivity of this assump-tion might be examined by redoing the virtual popula-tion analysis based upon a different M, perhaps M=0.3.From the sensitivity analysis one can determine the im-portance of particular parameters to the overall scien-tific advice. (Vaughan et al. 1987)

SeparabilitySéparabilitéSeparable

Age-structured stock assessment models trackchanges in fishing mortality by fish age and by fishingyear. Separability is the assumption, made in some ofthese models, that the fishing mortality matrix can bepartitioned into two components: An age-specific com-ponent that does not vary over time (i.e. a constant ex-ploitation pattern), and an annual multiplier that scalesthe age-specific pattern up or down. (Kimura and Scott1994)

Sequential Population Analysis (SPA)Analyse séquentielle des populationsAnálisis secuencial de poblaciones

Stock assessment methods consisting of a VPA anda statistical criterion for fitting indices of abundance (e.g.,ADAPT).

SetOpération de pêcheLance

Refers to a fishing operantion in which the gear isdeployed and retrieved once, usually for purse-seines orlonglines.

Sexual DimorphismDimorphisme sexuelDimorphismo sexual

Pertains to systematic differences between malesand females. Several species of tunas and billfishes showsexual dimorphism in growth or mortality.

ShrinkingShrinkingConstricción

A procedure applied in some assessment modelsin order to constrain how much parameter estimates canvary between consecutive years or between consecutiveages. Fishing mortality is sometimes extremely diffi-cult to estimate with adequate precision in the most re-cent years; “shrinking” allows the assessment scientistto constrain the F for the last year so that it does notdiffer substantially from, say, the average F for the pre-ceding 3-year period.

SimulationSimulationSimulación

The body of numerical techniques in which a cal-culation is performed using specified inputs in order tosimulate how a population of fish might react. Simula-tions may be deterministic (for each set of inputs therewill be one output of the calculation) or stochastic (mul-tiple calculations are performed to characterize the rangeof variability in the results). Sensitivity analyses are aform of simulation. Projections of the status of the popu-lation into the future is another type of simulation. Of-ten stochastic simulations are conducted in which anassessment calculation is repeated a large number oftimes, where each time the inputs are randomly selectedwith error. The range of outcomes in the calculationswill indicate how sure one is of the results. There areseveral ways of accounting for uncertainty in the inputs,such as bootstrapping, Bayesian methods, and MonteCarlo simulations. In either case, stochastic methods areused to determine confidence in the results of a particu-lar analysis.

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Size samplesEchantillons de tailleMuestras de talla

Refers to samples taken from the catch (from thelandings) in order to determine the size distribution ofthe catches. This information is important for stock as-sessments (particularly for age/size-structured methods)and management advice. Size samples are reported toICCAT as “Task II” data. When size samples are notavailable for a given type of fishing operation, Substitu-tions are used.

Skipjack (Katsuwonus pelamis)ListaoListado

A cosmopolitan tuna species forming schools inthe tropical and subtropical waters of the three oceans.Eastern and western stocks are assumed for assessment,separated at 30o W. Spawning is opportunistic through-out the year in vast areas of the Atlantic. Growth is vari-able and seasonal, and substantial differences in growthrates have been reported between areas. This species isassociated with floating objects, both natural and artifi-cial (FADs) which have been used extensively since theearly 1990s by purse seiners and baitboats. Skipjackcaught with FADs are usually associated with small yel-lowfin, bigeye and other tuna species.

SMT (Small Tunas)SMT (Thons mineurs)SMT (Pequeños túnidos)

These species (BLF, BLT, BON, BOP, BRS, CER,FRI, KGM, KGX, LTA, MAW, SSM, and WAH) aretypically exploited by coastal fisheries. For logisticalreasons, ICCAT does not conduct assessments of thesespecies, although some stocks are assessed by MemberStates.

SpawnersGéniteursReproductores

Refers to fish that are reproductively mature.

Spawning Potential Ratio (SPR)Ratio potentiel de reproductionRatio potencial de desove

The ratio of spawning potential per recruit undera given fishing regime relative to the spawning potentialper recruit with no fishing (also known as %MSP forMaximum Spawning Potential). SPR’s require informa-tion on natural mortality, growth, spawning potential atage and the relative vulnerability by age to fishing. Ifpossible, spawning potential per recruit is measured infecundity per recruit, but often spawning stock biomassper recruit (SSB/R see below) is an appropriate substi-tute. SPR and SSB/R are simple extensions to yield perrecruit (see below) in that there are two ways in whichrecruits can be used: they can be caught, in which casethey are part of the yield (yield per recruit), or they cansurvive, in which case they are part of the SPR, SSB/R.

SPR is expressed as a ratio of a fished condition to anunfished condition, thus the ratio varies from 0 to 1.Additionally, empirical studies have shown that for somepopulations SPR’s in the order of 20% to 30% may runthe risk of recruitment declines, thus there is a basis ofcomparison between populations. Therefore, FX%SPR fish-ing mortality rates are sometimes used as biological ref-erence points. (Note: SPR is sometimes used to mean“spawners per recruit”, but this usage should be avoidedand replaced by SSB/R). (Goodyear 1990)

Spawning Stock Biomass (SSB)Biomasse du stock reproducteur (SSB)Biomasa del stock reproductor (SSB)

The total weight of sexually mature fish in thepopulation (usually males and females combined, butsometimes female SSB, alone, is used). This quantitydepends on the abundance of year classes, the exploita-tion pattern, the rate of growth, both fishing and naturalmortality rates, the onset of sexual maturity, and envi-ronmental conditions. Many types of analyses that ad-dress reproductive (spawning) potential should use ameasure of production of viable eggs (e.g. fecundity).However, when such life-history information is lacking,SSB is used as a proxy.

Spawning stock biomass per recruit (SSB/R)Biomasse du stock reproducteur par recrue (SSB/R)Biomasa del stock reproductor por recluta (SSB/R)

The expected lifetime contribution to the spawn-ing stock biomass for the average recruit to the fishery.For a given exploitation pattern, rate of growth, matu-rity schedule and natural mortality, an equilibrium valueof SSB/R can be calculated for any level of F. SSB/Rdecreases monotonically with increasing F.

SSTSSTSST

Sea Surface Temperature.

STACFADSTACFADSTACFAD

Standing Committee on Finance and Administra-tion (ICCAT).

StandardizedStandariséEstandarizado

Refers to quantities that have been adjusted to bedirectly comparable to a unit that is defined as the “stan-dard” one. Nominal CPUE is standardized to removethe effect of factors which are known not to be related toabundance. This means that the effects of factors suchas vessel size or spatial availability, which clearly affectCPUE, are removed, e.g. by adjusting all observationsto the “standard vessel” in the “standard area”. A vari-ety of techniques are available for standardization suchas GLMs. (Cooke and Lankester 1996)

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StationaryStationnaireEstacionario

Refers to a parameter or life histrory characteris-tic that does not change over time. “Stationary” is closelyrelated to Equilibrium, although it is possible to haveone without the other. For example, yield-per-recruitcan be constant (if the fishing and natural mortality, ex-ploitation pattern, and growth remain stationary) but theoverall yield can vary over time if the number of re-cruits varies.

Statistical ModelModèle statistiqueModelo estadístico

A component of an estimation model, that definesthe criteria for how the observations are fitted. The typesof statistical models used in ICCAT analyses vary, in-cluding Least Squares, Maximum Likelihood, Bayesian,and Ad hoc procedures.

StatusEtatEstado

Refers to a determination made, on the basis ofstock assessment results, about the condition of the stockand of the fishery. Status determinations are often madewith respect to biological reference points (e.g., a stockis Overfished if its biomass is below the agreed limitreference point). The SCRS strives to report status withrespect to FMSY and BMSY because these quantities play arole in the Convention texts (see BMSY).

StochasticStochastiqueEstocástico

A process that has random components. For ex-ample, stock projections are usually made that futurerecruitment has a stochastic component.

StockStockStock

The term has different meanings. In general, astock is a biological unit of one species forming a groupof similar ecological characteristics and, as a unit, is thesubject of assessment and management. However, thereare many uncertainties in defining spatial and temporalgeographical boundaries for such biological units thatare 100% compatible with established data collectionand geopolitical systems. For this reason, the term stockis often synonym with assessment/management unit, evenif there is migration of the same species to and fromadjacent areas.

Stock AssessmentEvaluation de stockEvaluación de stock

The application of statistical and mathematicaltools to relevant data in order to obtain a quantitativeunderstanding of the status of the stock as needed to

make quantitative predictions of the stock´s reactions toalternative future regimes.

Stock-Recruitment RelationshipRapport stock-recrutementRelación stock-reclutamiento

A function that describes how recruitment varieswith changes in the reproductive output (or biomass) ofthe parental stock. Two common forms are the Beverton-Holt and the Ricker relationships. The stock-recruitmentrelationship is particularly important for the understand-ing of the sustainability of alternative harvesting regimes.Some stock assessment methods incorporate the estima-tion of such a relationship directly into the model, eitherexplicitly (e.g. some age-structured assessments) or im-plicitly (most stock production models). (Hayasi 1974)

Stock StructureStructure du stockEstructura de stock

(1) Refers to the geographical boundaries of thestocks assumed for assessment and management pur-poses (e.g., a species may be assumed to be comprisedof three separate stocks in the North Atlantic, South At-lantic, and Mediterranean Sea). (2) Refers to boundariesthat define self-contained populations in a genetic sense.

SubstitutionsSubstitutionsSubstituciones

Refers to the practice of substituting informationfrom one type of fishing operation for missing data inanother type of fishing operation. Substitutions are of-ten needed to obtain estimates of the total catch at sizefor a species.

Surface fisheriesPêcheries de surfacePesquerías de superficie

Refers to fisheries that target tunas or swordfishusing surface gears, such as surface longlines, baitboats,purse-seines and harpoons.

Surplus ProductionProduction excédentaireProducción excedente

The amount of biomass produced by the stock(through growth and recruitment) over and above thatwhich is required to maintain the total stock biomassconstant between consecutive time periods. See alsoReplacement Yield.

SurveyEchantillonnage scientifiqueProspección

Refers to the collection of data that is controlledby scientists, for example by collecting fish from researchvessels by following a pre-determined scientific design.See Fishery-independent.

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Survival RatioTaux de survieRatio de supervivencia

Ratio of recruits to spawners (or parental biom-ass) in a stock-recruitment analysis. Changes in sur-vival ratios indicate that the productivity of a stock ischanging.

SustainabilityDurabilitéSostenibilidad

Pertains to the ability to persist in the long-term.Sustainable fishing is a manner of fishing that ensuresthat future generations will also be able to fish. Be-cause fish populations exhibit natural variability, it isnot possible to keep all population and fishery attributesat a constant level simultaneously, thus sustainable fish-ing does not imply that the fishery and stock will persistin a constant equilibrium state. Because of natural vari-ability, even if FMSY could be achieved exactly each year,both catches and stock biomass would oscillate aroundtheir “equilibrium” MSY levels.

Swordfish (Xiphias gladius)EspadonPez espada

Swordfish are distributed widely in the AtlanticOcean and Mediterranean Sea, and range from Canadato Argentina on the western side, and from Norway toSouth Africa on the eastern side. Three stocks are as-sumed for assessment purposes: Mediterranean, Northand South Atlantic. They are typically caught on pelagiclonglines at night when they feed in surface waters.Spawning occurs in the warm tropical and subtropicalwaters throughout the year, although seasonality has beenreported. Swordfish are found in the colder northern wa-ters during summer months.

TTagMarqueMarca

A mark implanted on (or inside) a fish. Taggingdata are used to learn about a species´ biology but alsoas auxiliary data for stock assessments. “Conventional”or streamer tags are used to collect information aboutpoint of capture, point of recapture and growth. Moremodern tags use archival and/or pop-up technology.

Target Reference PointPoint cible de référenceNiveles de referencia previstos

A benchmark that should be achieved on averageaccording to a given set of management objectives.ICCAT´s implied targets are FMSY, BMSY and MSY. (Caddyand Mahon 1995)

Task I DataDonnées Tâche IDatos de la Tarea I

Atlantic tuna statistics collected by ICCAT con-sisting of: (i) Nominal annual catch of tuna and tuna likefish, by region, gear, flag and species, and, where pos-sible, by EEZ and High Seas; (ii) number of fishing ves-sels by size class, gear and flag, and, where possible, byEEZ and High Seas. In general, the primary responsi-bility for reporting catch and landing data rests on theflag State.

Task II DataDonnées Tâche IIDatos de la Tarea II

Atlantic tuna statistics collected by ICCAT con-sisting of: (i) Catch and effort statistics by small area(1ox1o or 5ox5o squares), gear, flag, species and month;(ii) actual size frequencies of samples caught by smallarea, gear, flag, species and month.

Taylor Series MethodMéthode de TaylorModelo de series de Taylor

See Delta Method.

Terminal FF terminalF terminal

Refers to fishing mortality values in the last yearfor which data are available in an assessment.

ThermoclineThermoclineTermoclina

A transition zone in the ocean between the upperwarm water layer and the lower cold water layer. Theposition of some fishing gears with respect to the ther-mocline can affect catchability.

ThresholdSeuilUmbral

A bilogical reference point used to indicate that aLimit reference point is being approached. (Note: Insome of the fisheries literature, “Threshold” is used todenote a “Limit”).

Total Allowable Catch (TAC)Total de prises permissiblesTotal admisible de capturas

A management control to limit the catch (yield)for the entire stock. TACs are typically partitioned intoquotas.

Total mortality rate (Z)Taux global de mortalitéTasa de mortalidad total

The sum of natural and fishing mortality rates.

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TransitionalTransitoireTransitorio

Refers to the non-equilibrium trajectory betweentwo equilibrium states. For example, equilibrium yieldanalyses might indicate that a given regulation will in-crease equilibrium yield by, say, two-fold. However,the transition between the two levels of yield will actu-ally involve a short-term loss in yield.

TuningCalibrageCalibración

The fitting of indices of abundance with catch data,using a stock assessment model. Tuning usually aims tominimize differences between the observed abundanceindices and the abundance predicted by the model.

UUncertaintyIncertitudesIncertidumbre

Uncertainty results from a lack of perfect knowl-edge of many factors that affect stock assessments, esti-mation of biological reference points, and management.Sources of uncertainty include measurement error (inobserved quantities), process error (or natural popula-tion variability, e.g. in recruitment), model error (mis-specification of assumed values or population modelstructure), estimation error (in population parameters orreference points, due to any of the preceding types oferrors), and implementation error (or the inability toimplement management controls for whatever reason).

UndersizedSous-tailleBajo talla

Refers to fish that are smaller than a minimum sizelimit established by regulation.

UN Fish Stocks Agreement (UNFSA)Accord de l´ONU sur les stocks (UNFSA)Acuerdo ONU sobre stocks de peces (UNFSA)

Agreement for the Implementation of the Provi-sions of the United Nations Convention on the Law ofthe Sea of 10 December 1982 Relating to the Conserva-tion and Management of Straddling Fish Stocks andHighly Migratory Fish Stocks (also known as the “Strad-dling Stocks Agreement”).

VVessel Monitoring System (VMS)Système de suivi des bateauxSistema de seguimiento de barcos

A system for tracking the position and operationof fishing vessels electronically, with real-time data trans-mission via satellite.

VirginViergeVirgen

Refers to an unfished condition of the stock in anequilibrium sense. For instance, Virgin Biomass isequivalent to the stock´s carrying capacity.

Virgin biomass (Bo)Biomasse viergeBiomasa virgen

A biological reference point. It is the long-termaverage biomass value expected in the absence of fish-ing mortality. In production models, B0 is also knownas carrying capacity.

Viscosity (of the stock)Viscosité (du stock)Viscosidad (del stock)

A term used to describe the notion that, through-out its area of distribution, mixing of individuals is nei-ther complete and instantaneous, nor inexistent. Thus,what a fishery does in a particular subarea of the stockimpacts the entire stock in a time scale and to a degreethat are a function of the stock´s “viscosity”. ICCATdoes not have quantitative measures of viscosity, and itsassessments are not spatially-structured, so that this con-cept is only used in a qualitative fashion. (Fonteneau etal. 1998; MaCall 1990)

Virtual Population Analysis (VPA)Analyse des populations virtuellesAnálisis de población virtual

An algorithm for computing historical fishingmortality rates and stock sizes by age, conditioned oncatches, natural mortality, and certain assumptions aboutmortality for the last year and last age group. A VPAessentially reconstructs the history of each cohort, as-suming that the observed catches are exact and knownwithout error. (Powers and Restrepo 1992)

WWhite marlin (Tetrapturus albidus)Makaire blancAguja blanca

A billfish species found throughout tropical andtemperate waters of the Atlantic Ocean and adjacent seas.Their range is almost identical to that of blue marlin,although they seem to be less abundant in the easternAtlantic. A single Atlantic-wide stock is assumed forassessment. White marlin occur only in the AtlanticOcean, which is not the case for blue marlin and sail-fish. Although white marlin are considered to be rareand solitary compared to schooling tunas, they are knownto occur in small groups of several fish. Spawning oc-curs in tropical and subtropical waters in mid- to latespring. White marlin are found predominately in the openocean near the surface and are caught most frequentlyas a by-catch by the offshore longline fisheries whichtarget tropical or temperate tunas. Significant by-catch

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landings are also made by offshore longline fisheriesthat target swordfish, particularly in the west AtlanticOcean.

XXBTXBTXBT

Expendable baty-thermograph, an instrument thatrecords water temperature against depth.

XSAXSAXSA

“Extended Survivors Analysis.” A stock assess-ment program based on VPA and tuning of abundanceindices. (Darby and Flatman 1994)

YYear ClassClasse annuelleClase anual

The fish spawned or hatched in a given year. Seecohort.

Yellowfin (Thunnus albacares)AlbacoreRabil

A cosmopolitan tuna species distributed mainlyin the tropical and subtropical oceanic waters of the threeoceans, where they form large schools. Smaller fish formsurface schools mixed with skipjack and young bigeye,while larger fish are found in surface and sub-surfacewaters. A single Atlantic-wide stock is assumed for as-sessment. The main spawning ground is the equatorialzone of the Gulf of Guinea, with spawning occurringfrom January to April. Spawning also occurs from Mayto November in the Gulf of Mexico and southeasternCaribbean Sea. From the Gulf of Guinea, juveniles movetowards more coastal waters off Africa. Later they maymigrate westward to the American coasts, to return tothe east Atlantic fishing grounds for spawning when theyreach maturity.

YieldProductionRendimiento

Catch in weight.

Yield per Recruit (Y/R)Production par recrueRendimiento por recluta

The expected lifetime yield for the average recruit.For a given exploitation pattern, rate of growth, and natu-ral mortality, an equilibrium value of Y/R can be calcu-lated for each level of F. Y/R analyses play an impor-tant role in advice for management, particularly as itrelates to minimum size controls.

AcronymsAssessment Symbols andAcronyms (see definitions)

B BiomassBMSY Biomass at MSYBo Virgin (unexploited level) biomassCA Cohort analysisCAA Catch at ageCAS Catch at sizeCPUE Catch per unit effort (catch rate)F Fishing mortality rateK Carrying capacity of the stockL

�Asymptotic (maximum) length

M Natural mortality rateMSY Maximum sustainable yieldq Catchabilityr (Intrinsic) growth rateSPA Sequential Population AnalysisSPR Spawners per recruitSSB Spawning stock biomassSSB/R Spawning stock biomass per recruittc Age of recruitmentVPA Virtual population analysisY/R Yield per recruitZ Total mortality rate

ICCAT Species CodesALB Albacore Thunnus alalunga.BET Bigeye tuna Thunnus obesus.BFT Bluefin tuna Thunnus thynnus thynnus.BGT Big tunas, unclassified.BIL Billfishes, unclassified.BLF Blackfin tuna Thunnus atlanticus.BLM Black marlin Makaira indica.BLT Bullet tuna Auxis rochei.BON Atlantic bonito Sarda sarda.BOP Plain bonito Orcynopsis unicolor.BUM Atlantic blue marlin Makaira nigricans.CER Cero Scomberomorus regalis.FRI Frigate tuna Auxis thazard.KGM King mackerel Scomberomorus cavalla.KGX Scomberomorus, unclassified.LTA Atlantic black skipjack Euthynnus alletteratus.MAW W African Spanish mackerel Scomberomorus tritor.OTH Mixed or unknown species.SAI Atlantic sailfish Istiophorus albicans.SBF Southern bluefin tuna Thunnus maccoyii.SKJ Oceanic skipjack Katsuwonus pelamis.SPF Spearfish Tetrapturus pfluegeri and T. belone.SSM Spotted Spanish mackerel Scomberomorus

maclatus.SWO Broadbill swordfish Xiphias gladius.WAH Wahoo Acanthocybium solandri.WHM Atlantic white marlin Tetrapturus albidus.YFT Yellowfin tuna Thunnus albacares.YOU Young tunas, unclassified.

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Fishing Gears and CodesBB Baitboat. Pole-and-line fishing, chumming live bait for

attracting schools of tuna.

GILL Gillnet. A set of nets (either drifting or afixed to thebottom) used for entangling fish.

HAND Handline. Fishing lines held by had, with or withoutchumming live bait.

HARP Harpoon. Harpoons or spears thrown either by handor an auxiliary mechanism to catch fish.

HS Haul seine. Beach seine.

LL Longline. A set of lines to which branch lines with hooksare attached.

MWT Mid-water trawl. A net that is trawled below the sur-face, but not touching the bottom.

PS Purse seine. A seine with a purse-like mechanism at thebottom, used to close the net after encircling a school.

RR Rod-and-reel. Rod and line fishing (sports fishing).

TRAP Trap. Fixed gear anchored to the bottom, usually con-taining a guide net that leads fish into an enclosure.

TRAW Trawl. A net that is trawled over the bottom.

TROL Troller. A boat equipped with lines that have one ormore hooks, wich are trolled from the running boat.

Organizations/InstitutesAZTI Instituto Tecnologico Pesquero y Alimentario.

(www.azti.es)

CCAMLR Commission for the Conservation of AntarcticMarine Living Resources. (www.ccamlr.org)

CCSBT Convention for the Conservation of Southern Blue-fin Tuna. (www.home.aone.net.au/ccsbt)

CITES Convention on International Trade in EndangeredSpecies of Wild Fauna and Flora. (www.cites.org)

COFI Committee on Fisheries, United Nations.

CRODT Centre de Recherches Océanographiques Dakar-Thiaroye, Sénégal.

CSIRO Council of Scientific and Industrial Research Orga-nization, Australia. (www.marine.csiro.au)

CWP Coordinating Working Party on Fishery Statistics (agroup composed by FAO and regional agencies involvedin the collection and compilation of fishery statistics).(www.fao.org/fi/body)

DFO Department of Fisheries and Oceans, Canada. (www.dfo-mpo.gc.ca)

EU European Union. (www.europa.eu.int)

FAO Food and Agriculture Organization. (www.fao.org/fi)

FONAIAP Fondo Nacional de Investigaciones Agropecuarias(Venezuela).

GFCM General Fisheries Commission of the Mediterranean.

IATTC Inter-American Tropical Tuna Commission.(www.iattc.org)

ICES International Council for the Exploration of the Seas.(www.ices.dk)

IBAMA Instituto Brasileiro do Meio Ambient e dos RecursosNaturais Renováveis, Brazil. (www.ibama.gov.br)

IEO Instituto Español de Oceanografía, Spain. (www.ieo.es)

IFREMER Institut Français de Recherche pour l´Exploitationde la Mer, France. (www.ifremer.fr)

INAPE Instituto de Pesca Marítima, Uruguay.

IOC Intergovernmental Oceanographic Commission.

IOF Institute of Oceanography and Fisheries, Croatia.

IOTC Indian Ocean Tuna Commission. (www.seychelles.net/iotc)

IRD Institut de Recherche pour le Développement, France(formerly ORSTOM). (www.ird.fr)

ISPM Institut Scientifique des Pêches Maritimes, Maroc.

NAFO Northwest Atlantic Fisheries Organization.(www.nafo.ca)

NRIFSF National Research Institute of Far Seas Fisheries,Japan. (www.enyo.affrc.go.jp)

NMFS National Marine Fisheries Service, USA.(www.nmfs.gov)

ORSTOM Office de la Recherche Scientifique et TechniqueOutre-Mer, France (now IRD).

SPC Secretariat of the Pacific Community. (www.spc.org.nc/oceanfish)

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