Updated White Marlin (Tetrapterus Albidus) and Blue Marlin (Makaira Nigricans) Catch Rates from the U.S

SCRS/2006/066 Col. Vol. Sci. Pap. ICCAT, 60(5): 1663-1677 (2007)

UPDATED WHITE MARLIN (TETRAPTERUS ALBIDUS) AND BLUE MARLIN (MAKAIRA NIGRICANS) CATCH RATES FROM THE U.S. PELAGIC LONGLINE IN THE NORTHWEST ATLANTIC AND GULF OF MEXICO 1986-2005

Guillermo A. Diaz and Mauricio Ortiz1

SUMMARY

Indices of abundance of white and blue marlin for the U.S. pelagic longline fishery in the Northwest Atlantic and U.S. Gulf of Mexico are presented for the period 1986-2005. The index of weight (kg) per thousand hooks was estimated from the number of marlin caught reported by the commercial fleet through a logbook reporting system, and from mean annual weight estimated from observations obtained by scientific observers aboard longline vessels since 1992 (Pelagic Observer Program). The standardization analysis procedure included the following variables: year, area of fishing, gear characteristics (e.g., main line length, number of hooks, light sticks, etc.), and fishing characteristics (e.g., bait type, target species, etc.). The standardized indexes were estimated using Generalized Linear Mixed Models under a Delta lognormal model approach. White marlin CPUE series showed a declining trend from 1986 though 2000 and remained fairly constant since with a slight increase in 2004 and 2005. Blue marlin CPUE showed increase from 1985 through 1993 followed by a decline through year 2000; while years 2004 and 2005 showed an upward trend.

RÉSUMÉ

Ce document présente les indices d’abondance du makaire blanc et du makaire bleu de la pêcherie palangrière pélagique américaine dans l’Atlantique Nord-Ouest et dans le Golfe du Mexique des Etats-Unis pour la période 1986-2005. L’indice de poids (kg) par mille hameçons a été estimé d’après le nombre de makaires capturés, déclarés par la flottille commerciale par le biais d’un système de déclaration des livres de bord et d’après le poids annuel moyen estimé d’après les observations obtenues par des observateurs scientifiques embarqués à bord de palangriers depuis 1992 (Programme d’observateurs pélagiques). La procédure d’analyse de standardisation incluait les variables suivantes : l’année, la zone de pêche, les caractéristiques des engins (par exemple, longueur de la ligne principale, nombre d’hameçons, baguettes lumineuses etc.) ainsi que les caractéristiques de pêche (par exemple, type d’appât, espèce cible, etc.). Les indices standardisés ont été estimés à l’aide de modèles linéaires généralisés mixtes dans le cadre d’une approche de modèle delta-lognormal. Les séries de CPUE du makaire blanc présentaient une tendance décroissante de 1986 jusqu’en 2000 et demeuraient assez constantes depuis lors, avec une légère augmentation en 2004 et 2005. La CPUE du makaire bleu affichait une augmentation de 1985 jusqu’en 1993, suivie d’un déclin jusqu’en 2000, alors que les années 2004 et 2005 montraient une tendance à la hausse.

RESUMEN

Se presentan los índices de abundancia de la aguja blanca y la aguja azul para la pesquería de palangre pelágico estadounidense en el Atlántico noroeste y el Golfo de México estadounidense para el periodo 1986-2005. El índice de peso (kg) por mil anzuelos fue estimado a partir del número de marlines capturados declarado por la flota comercial a través del sistema de comunicación de cuadernos de pesca, y del peso anual medio estimado a partir de las observaciones obtenidas por los observadores científicos a bordo de palangreros desde 1992 (Programa de observadores pelágicos). El procedimiento del análisis de estandarización incluía las siguientes variables: año, área de pesca, características del arte (por ejemplo, longitud de la línea madre, número de anzuelos, bastones de luz, etc.), y características pesqueras (por ejemplo tipo de cebo, especie objetivo, etc.). Los índices estandarizados se

1 U.S. Department of Commerce, National Oceanographic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, Sustainable Fisheries Division, 75 Virginia Beach Drive, Miami, FL 33149 USA. [email protected]. *This is a Sustainable Fisheries Division Contribution SFD No. SFD-2006-021

1663 estimaron utilizando modelos lineales generalizados mixtos bajo un enfoque del modelo Delta lognormal. La serie de CPUE de la aguja blanca mostraba una tendencia descendente desde 1986 hasta 2000 y permanecía bastante constante desde entonces, con un ligero incremento en 2004 y 2005. La CPUE de la aguja azul mostraba un incremento desde 1985 hasta 1993 seguido de un descenso hasta el año 2000; los años 2004 y 2005 mostraban una tendencia ascendente.

KEYWORDS

Catch/effort, U.S. commercial long lining, white marlin, blue marlin

1. Introduction

The U.S. longline fleet operates over a wide geographical range of the western north Atlantic ocean and the Caribbean targeting swordfish and tunas. Although billfish are now not targeted nor landed by the U.S. longline fleet, they are still incidentally caught (bycatch). Bycatch data collected from the U.S. pelagic longline fleet has been previously used to develop standardized indices of abundance for white and blue marlin (Cramer 1998, Ortiz and Scott, 2003; Diaz and Ortiz, 2006). This information of relative abundance can be used to tune stock assessment models. The present report documents the analytical methods applied and updates the blue and white marlin indices of abundance presented in document SCRS/2005/031 through 2005.

2. Materials and Methods

Hoey and Bertolino (1988) described the U.S. longline fleet and numerous authors have reviewed the available catch and effort data (e.g., Hoey et al. 1989, Scott et al. 1993, Cramer and Bertolino 1998, Ortiz et al. 2000, Ortiz and Diaz 2004). Logbook records from the U.S. pelagic longline fleet were collected on a voluntary basis from 1986 to 1991, and thereafter the submission of logbook records became mandatory for all vessels. The main targets of the U.S. longline fleet are swordfish (Xiphias gladius), yellowfin tuna (Thunnus albacares), and other tunas. Although marlin are not retained by the U.S. fleet, fishers are still required to record their incidental catch. Each record in the Pelagic Longline Logbook (PLL) data set provides information of the catch in numbers of all species caught including bycatch, fishing effort (as total number of hooks), gear configuration (main line length, number of hooks per basket, etc), date, time, and geographical location of a longline set.

Since 1992, an average of 5-8% of the U.S. pelagic longline fleet is sampled by the Pelagic Observer Program (POP). The POP places trained observers aboard commercial longliners to record detailed information on gear characteristics, fishing operations and biological information of the catch and bycatch that would not otherwise be collected (Lee and Brown 1998).

The ICCAT-SCRS Billfish Species Group has recommended that when possible, indices of abundance be estimated in both weight and number of fish. The PLL only records catch in numbers. Thus, to convert number of marlin caught to weight we used reported lower jaw-fork length (LJFL) by the POP of marlin caught by the sampled fraction of the U.S. pelagic longline fleet. The total number of blue and white marlin recorded by the POP program in the period 1992-2005 was 1,850 and 3,155, respectively. Lower jaw-fork lengths were converted to weight using the size-weight relationships (for combined sex) developed by Prager et al. (1995). Mean weight was estimated for each year-area-season stratum with at least 20 observations (measurements), for those cells with less than 20 observations then a mean weight for the year-area or year stratum was used. For years previous to 1992 (before the implementation of the POP), the mean weight values for 1992 were applied.

The longline fishing grounds of the U.S. fleet extends from the Grand Banks in the north Atlantic to approximately 5-10o S, off the South American coast, and include the Caribbean Sea and the Gulf of Mexico. For analysis purposes, nine geographical areas were defined as follows (Figure 1): Caribbean, Gulf of Mexico, Florida east coast, South Atlantic bight, Mid-Atlantic Bight, Northeast coastal, Northeast distant, Sargasso-North central Atlantic, and Southern offshore area. Since 1999, the U.S. has implemented time-area restrictions for the pelagic longline fleet (Figure. 1). These restriction included three permanent closure: (1) the Desoto Canyon (Gulf of Mexico) since November 1st 2000, (2) the U.S. EEZ within the Florida East Coast area since March 1st 2001, and (3) the entire Northeast distant area since 2001 (the Northeast distant area is only open to U.S.

1664 longline fishing boats participating in fishing gear configuration experiments), and two temporary closures imposed in 1999: (1) the Charleston Bump from Feb. 1st to April 30th and (2) the Bluefin tuna protection area closed from June 1st to June 30th. Calendar quarters were used to account for seasonal fishery distribution through the year (Jan-Mar, Apr-Jun, Aug-Sep, Oct-Dec). Besides year, geographical area, and season, other factors describing gear configurations, target species, and type and size of vessels (operational procedure) were included in the factor selection process. Factors that were continuous variables (e.g. length of the mainline, density of light sticks, etc.), were transformed into discrete variables by defining ranges. Therefore, all factors included in the final models were treated as categorical.

Relative indices of abundances for both the PLL and POP data were estimated by a GLM approach assuming a delta-lognormal model distribution. The delta model fits separately the proportion of positive sets (proportion of sets that caught at least one marlin) assuming a binomial error distribution and the catch rate estimated only from positive sets assuming a lognormal error distribution. The standardized index is the product of these model- estimated components.

Ortiz and Scott (2003), and Diaz and Ortiz (2006) used a step-wise procedure to determine the set of systematic factors and interactions that significantly explained the observed variability in the proportion of positive sets and the catch rates. The significance of a factor added to the model in the step-wise procedure was tested using a Chi-square test. They conditioned the final selection of explanatory factors to: 1) the relative percent of deviance explained by adding the factor in evaluation, 2) the Chi-square test of significance, and 3) the Type III test of significance within the final specified model. After selecting the fixed factors, all possible interactions were evaluated, in particular interactions between the Year effect and other factors.

To update the CPUE series presented in document SCRS/2005/031, the present study used the same significant factors determined in the mentioned document. Besides year, area, and season, the other factors included in the models were:

Target: defined based on the proportion of the number of swordfish caught to the total number of fish (tunas and swordfish) per set as four discrete categories: 0-25%, 25-50%, 50-75% and 75-100%.

OP (Operations Procedure): a categorical classification of US longline vessels based on their fishing configuration, type and size of the vessel, main area of operations, and main target species.

Light: a proportion of hooks in a set with light sticks as three discrete categories. mainline: categorical variable defined by the length of the main line. bait kind: categorical variable that explained the different type/s of bait used in the set (e.g. mackerel, squid, sardine, scad, and different combinations of bait kind, etc.).

Table 1 provides a list of the fixed factors and interactions included in each model. All interaction terms that included the year factor were treated as random interactions. Analysis were done using the GLIMMIX and MIXED procedures from the SAS® Statistical computer software (SAS Institute Inc. 1997).

3. Results and discussion

A total of 235,822 PLL set records were used in the present analysis. Of these, 19,863 (8.4%) reported catching at least one white marlin and 20,163 (8.6%) at least one blue marlin. The POP data set consisted of 7,141 set records; of which 1,615 (22.6%) reported white marlin catch(es) and 1,180 (16.5%) reported blue marlin catch(es).

White marlin standardized and nominal CPUE (in number of fish and weight) series estimated from the PLL data are presented in Tables 2 and 3, and Figures 2 and 3. Coefficients of variation for the estimated standardized CPUE ranged from 24% to 43%. The same information for blue marlin is shown in Tables 4 and 5 and Figure 4 and 5. For blue marlin, the coefficients of variation ranged from 22% to 49%. For each species, nominal and standardized CPUE series for the PLL data showed similar trends, and the nominal series were within the 95% confidence interval of the standardized series during the entire time period analyzed.

1665 A comparison of the estimated standardized CPUE series (in weight) from the PLL and POP data for each species is shown in Figure 6. For comparison purposes, the CPUE series from the PLL and POP data were scaled to their mean of the overlapping time period (1992-2005). In general, 95% confidence intervals of the CPUE series were wider for the POP estimates in both species. In the case of white marlin, both CPUE series showed a close correlation with only one POP estimate outside the 95% CI of the PLL series (year 1994) and a different trend only in the period 1994-1995. Blue marlin CPUE series also showed a good correlation. Only POP estimates for years 1993 and 1994 laid outside the 95% confidence interval of the POP series. Different trends were observed for the period 1994-1996.

For both species, CPUE series showed a declining trend through the late 90's and seemed to have stabilized at low levels until 2003. However, years 2004 and 2005 showed increasing trends for both species. These increases were more noticeable in the POP CPUE series.

References

CRAMER, J. 1998. Large pelagic logbook catch rate indices for Billfish. Col. Vol. Sci. Pap. ICCAT, 47: 301- 307. CRAMER, J. and A. Bertolino. 1998. Standardized catch rates for swordfish (Xiphias gladius) from the U.S. longline fleet through 1997. Col. Vol. Sci. Pap. ICCAT, 49(1):449-456. DIAZ, G. A. and M. Ortiz. 2006. Updated white marlin (Tetrapturus albidus) and blue marlin (Makaira nigricans) catch rates from the U.S. pelagic longline in the nnorthwest Atlantic and Gulf of Mexico.. Col. Vol. Sci. Pap. ICCAT, 59(1):196-210. HOEY, J.J. and A. Bertolino. 1988. Review of the U.S. fishery for swordfish, 1978 to 1986. Col. Vol. Sci. Pap. ICCAT, 27:256-266. HOEY, J.J., R. Conser and E. Duffie. 1989. Catch per unit effort information from the U.S. swordfish fishery. Col. Vol. Sci. Pap. ICCAT, 29:195-249. LEE, D.W. and C.J. Brown. 1998. SEFSC Pelagic Observer Program Data Summary for 1992-1996. NOAA Tech. Memo. NMFS-SEFSC-408, 21 pp. MCCULLAGH, P. and J.A. Nelder. 1989. Generalized Linear Models 2nd edition. Chapman & Hall. ORTIZ, M. J. Cramer, A. Bertolino and G. P. Scott. 2000. Standardized catch rates by sex and age for swordfish (Xiphias gladius) from the U.S. Longline Fleet 1981-1998. Col. Vol. Sci. Pap. ICCAT, 51:1559-1620. ORTIZ, M and G. P. Scott. 2003. Standardized catch rates for white marlin (Tetrapturus albidus) and blue marlin (Makaira nigricans) from the pelagic longline fishery in the northwest Atlantic and the Gulf of Mexico. Col. Vol. Sci. Pap. ICCAT, 55(2):511-528. ORTIZ, M and G. A. Diaz. 2004. Standardized catch rates for yellowfin tuna (Thunnus albacares) from the U.S. pelagic longline fleet. Col. Vol. Sci. Pap. ICCAT, 56(2):660-675. PRAGER, M.H., E. D. Prince and D. W. Lee. 1995. Empirical length and weight conversion equation: for blue marlin, white marlin, and sailfish from the North Atlantic Ocean. Bull of Mar. Sci. 56(1):201-210. SAS Institute Inc. 1997, SAS/STAT® Software: Changes and Enhancements through Release 6.12. Cary, NC, USA:Sas Institute Inc., 1997. 1167 pp. SCOTT, G. P., V. R. Restrepo and A. R. Bertolino. 1993. Standardized catch rates for swordfish (Xiphias gladius) from the US longline fleet through 1991. Col. Vol. Sci. Pap. ICCAT, 40(1):458-467.

1666 Table 1: List of fixed factors and interactions included in the proportion positive and catch rate models for each marlin species and each data source. Refer to text for a detailed explanation of each factor.

Pelagic Longline Logbook Pelagic Observer Program White marlin Blue Marlin White marlin Blue Marlin Prop. Prop. Catch rate Catch rate Prop. Posit Catch rate Prop. Posit Catch rate Posit Posit Year Year Year Year Year Year Year Year Area Area Area Area Area Area Area Area Season Season Season OP Season OP Season mainlength OP OP OP Lights OP Target OP OP Target Lights Target Year*Area Bait Year*Area Year*Area Year*Area Year*Area Year*Area Year*Area Year*OP Target Year*OP Year*Seas. Year*OP Year*OP Year*OP Year*OP Area*OP Light Area*Seas. Area*Seas. Area*Seas. Year*Light Year*Area Area*OP Area*OP

Table 2. White marlin nominal and standardized catch rate (number of fish/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Longline Logbook program data.

Year Nominal Standardized Coefficient Upper 95% Lower 95% CPUE CPUE Variation CI CI 1986 0.604 0.870 31.2% 1.613 0.469 1987 0.404 0.360 31.0% 0.660 0.196

1988 0.342 0.317 32.3% 0.595 0.169

1989 0.392 0.419 29.5% 0.748 0.235

1990 0.314 0.371 30.4% 0.673 0.204

1991 0.334 0.335 31.1% 0.614 0.182

1992 0.388 0.428 28.7% 0.752 0.244

1993 0.395 0.383 29.4% 0.682 0.215

1994 0.303 0.270 32.1% 0.506 0.145

1995 0.331 0.271 32.1% 0.507 0.145

1996 0.259 0.217 33.9% 0.420 0.112

1997 0.250 0.189 35.4% 0.377 0.095

1998 0.187 0.190 35.2% 0.378 0.096

1999 0.245 0.244 33.6% 0.469 0.127

2000 0.159 0.135 40.5% 0.295 0.062

2001 0.121 0.108 44.1% 0.251 0.046

2002 0.220 0.153 39.2% 0.326 0.072

2003 0.114 0.120 43.1% 0.274 0.053

2004 0.143 0.175 37.9% 0.364 0.084

2005 0.167 0.162 38.8% 0.343 0.077

1667 Table 3. White marlin nominal and standardized catch rate (kg/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Longline Logbook program data.

Year Nominal CPUE Standardized Coefficient Upper 95% Lower 95% CPUE Variation CI CI 1986 11.122 15.820 28.8% 27.833 8.992

1987 7.567 6.568 25.9% 10.950 3.939

1988 6.343 5.754 26.5% 9.694 3.416

1989 7.389 7.667 25.2% 12.602 4.664

1990 5.822 6.828 25.6% 11.304 4.125

1991 6.248 6.225 25.7% 10.334 3.750

1992 7.260 7.997 24.6% 12.979 4.927

1993 7.259 7.092 24.8% 11.564 4.349

1994 7.286 6.209 25.6% 10.272 3.753

1995 6.819 5.373 25.7% 8.906 3.241

1996 5.352 4.529 26.0% 7.554 2.715

1997 5.242 4.045 26.4% 6.794 2.408

1998 4.139 4.277 26.2% 7.166 2.553

1999 5.219 5.254 26.3% 8.806 3.135

2000 3.057 2.583 28.0% 4.478 1.491

2001 2.463 2.218 28.7% 3.894 1.263

2002 4.007 2.803 27.9% 4.851 1.620

2003 1.734 1.869 29.1% 3.306 1.057

2004 2.632 3.130 27.8% 5.400 1.815

2005 3.183 2.998 28.0% 5.197 1.730

1668

Table 4. Blue marlin nominal and standardized catch rate (number of fish/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Longline Logbook program data.

Nominal Standardized Coefficient Upper 95% Lower 95% Year CPUE CPUE Variation CI CI 1992 14.080 12.239 31.2% 22.521 6.652 1993 13.806 10.495 26.9% 17.821 6.181

1994 11.022 7.193 30.4% 13.035 3.970

1995 18.527 13.398 26.8% 22.680 7.914

1996 12.123 10.696 29.7% 19.124 5.982

1997 16.154 10.839 30.4% 19.657 5.977

1998 15.300 11.701 30.8% 21.373 6.406

1999 21.427 14.828 28.0% 25.686 8.560

2000 13.146 7.038 32.5% 13.256 3.737

2001 3.342 3.486 37.3% 7.172 1.694

2002 13.239 8.077 32.8% 15.318 4.259

2003 5.152 5.083 32.2% 9.524 2.713

2004 13.177 10.563 27.8% 18.228 6.121

2005 14.430 12.456 29.0% 21.991 7.055

1669 Table 5. Blue marlin nominal and standardized catch rate (kg/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Longline Logbook program data.

Year Nominal Standardized Coefficient Upper 95% Lower 95% CPUE CPUE Variation CI CI 1986 19.804 26.493 29.8% 47.505 14.775

1987 26.499 14.299 25.4% 23.592 8.666

1988 22.208 16.164 24.9% 26.411 9.893

1989 18.418 21.716 23.5% 34.532 13.656

1990 18.631 23.438 23.3% 37.131 14.795

1991 17.057 16.148 24.4% 26.144 9.974

1992 27.587 34.750 22.7% 54.411 22.193

1993 36.882 41.726 22.7% 65.310 26.658

1994 34.157 33.903 23.4% 53.826 21.355

1995 29.293 26.874 23.9% 43.070 16.769

1996 34.540 23.546 24.3% 38.020 14.582

1997 22.971 16.214 24.8% 26.425 9.949

1998 14.652 12.841 25.23% 21.098 7.816

1999 12.882 12.817 25.6% 21.228 7.738

2000 11.370 10.498 26.0% 17.523 6.290

2001 5.824 5.944 27.4% 10.183 3.470

2002 12.653 9.448 26.7% 15.973 5.588

2003 6.153 5.940 28.2% 10.335 3.414

2004 6.773 9.113 27.4% 15.606 5.322

2005 8.521 11.853 27.4% 20.307 6.918

1670 Table 6. White marlin nominal and standardized catch rate (kg/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Observer Program data

Nominal Standardized Coefficient Upper 95% Lower 95% Year CPUE CPUE Variation CI CI 1992 14.080 12.239 31.2% 22.521 6.652 1993 13.806 10.495 26.9% 17.821 6.181

1994 11.022 7.193 30.4% 13.035 3.970

1995 18.527 13.398 26.8% 22.680 7.914

1996 12.123 10.696 29.7% 19.124 5.982

1997 16.154 10.839 30.4% 19.657 5.977

1998 15.300 11.701 30.8% 21.373 6.406

1999 21.427 14.828 28.0% 25.686 8.560

2000 13.146 7.038 32.5% 13.256 3.737

2001 3.342 3.486 37.3% 7.172 1.694

2002 13.239 8.077 32.8% 15.318 4.259

2003 5.152 5.083 32.2% 9.524 2.713

2004 13.177 10.563 27.8% 18.228 6.121

2005 14.430 12.456 29.0% 21.991 7.055

1671 Table 7. Blue marlin nominal and standardized catch rate (kg/1000 hooks), coefficient of variation and limits of the 95% confidence interval (CI) of the standardized index from the Pelagic Observer Program data.

Year Nominal Standardized Coefficient Upper 95% Lower 95% CPUE CPUE Variation CI CI 1992 21.543 24.656 29.8 44.215 13.749 1993 26.649 22.230 27.1 37.826 13.065

1994 20.563 17.528 29.6 31.279 9.822

1995 37.515 27.015 28.4 47.111 15.491

1996 60.998 40.137 29.1 71.027 22.681

1997 43.873 34.211 29.4 60.846 19.236

1998 24.030 19.615 31.5 36.278 10.605

1999 34.088 23.488 30.8 42.890 12.863

2000 28.520 20.325 30.6 36.971 11.174

2001 8.199 10.053 35.0 19.840 5.094

2002 40.218 23.511 32.0 43.868 12.600

2003 16.798 12.155 34.6 23.817 6.203

2004 22.537 17.394 30.2 31.422 9.629

2005 31.537 32.170 30.8 58.719 17.625

1672

Figure 1: Geographical area classification used in the analysis of the US Pelagic Longline fleet data: Caribbean (CAR), Gulf of Mexico (GOM), Florida East Coast (FEC), South Atlantic Bight (SAB), Mid-Atlantic Bight (MAB), Northeast Coastal waters (NEC), Northeast Distant waters (NED), Sargargasso-North Central Atlantic (SAR-NCA), and Southern Offshore area (SOF). Blue areas correspond to time-area restrictions to the U.S. longline fishing fleet: (1) Desoto Canyon, (2) Florida East Coast, (3) Charleston Bump, (4) Bluefin tuna protection area, (5) Northeast Distant waters area.

1673 1.5 White marlin

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1674

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1675 Blue marlin

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1676

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Figure 6. Standardized CPUE (kg/1000 hooks) series and 95% confidence intervals estimated from the Pelagic Longline Logbook data (blue lines and symbols) and the Pelagic Observer Program data (red line and symbols) for a) white marlin and b) blue marlin. Both series were scaled to their mean value of the overlapping years (1992-2004). Vertical arrows show years when ICCAT recommendations for billfish 97-9, 98-10 and 00-13 entered into force.

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