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64when the true dynamics includes a stock recruitment relationship causes a greater loss in yield than fishing at levels corresponding toMSY estimated from the stock-recruitment relationship sensitivity when recruitment is in fact independent of spawning biomass(Figure B-9).The MSY calculations indicate that, theoretically, at least, catches could be increased if the fishing effort were directed towardlonglining and purse-seine sets on yellowfin associated with dolphins. This would also increase the SBR levels.The MSY has been stable during the assessment period (Figure B-7), which suggests that the overall pattern of selectivity has not varieda great deal through time. However, the overall level of fishing effort has varied with respect to the level corresponding to MSY.The SBR corresponding to MSY decreased substantially from the previous assessment indicating that the results are sensitive to thechange in methodology. The change is attributed to the method used to model selectivity. However, the SBR relative to SBR correspondingto MSY and the F multiplier are similar to the previous assessment.If a stock-recruitment relationship is assumed, the outlook is more pessimistic, and current biomass is estimated to be below thelevel corresponding to the MSY. The status of the stock is also sensitive to the value of adult natural mortality, the method used tomodel selectivity, and the assumed length of the oldest age modeled (29 quarters).Under current levels of fishing mortality (2006-2008), the spawning biomass is predicted to slightly decrease, but remain above thelevel corresponding to MSY (F MSY ). It is predicted that the catches will be higher over the near term than in 2008, but will declineslightly in the future (Figure B-6). Fishing at F MSY predicted to reduce the spawning biomass slightly from that under current effortand produces slightly higher catches.Key results1. The stock assessment method has changed to Stock Synthesis2. The estimates of the key management quantities are similar to the previous assessments3. Estimates of absolute biomass are lower than estimated in previous years4. The SBR corresponding to MSY has reduced substantially from previous assessments and the reduction is attributed to thenew method to model selectivity5. There is uncertainty about recent and future recruitment and biomass levels and there are retrospective patterns of overestimatingrecent recruitment.6. The recent fishing mortality rates are close to those corresponding to the MSY and SBR is above the level correspondingto the MSY.7. Increasing the average weight of the yellowfin caught could increase the MSY.8. There have been two, and possibly three, different productivity regimes, and the levels of MSY and the biomasses correspondingto the MSY may differ between the regimes. The population may have recently switched from the high to an intermediateproductivity regime.9. The results are more pessimistic if a stock-recruitment relationship is assumed.10. The results are sensitive to the natural mortality assumed for adult yellowfin, the method used to model selectivity, and thelength assumed for the oldest fish.
FIGURE B-1. Total catches (retained catches plus discards) for the purse-seine fisheries, and retained catches for the pole-and-lineand longline fisheries, of yellowfin tuna in the eastern Pacific Ocean, 1975-2008. The purse-seine catches are adjusted to the speciescomposition estimate obtained from sampling the catches. The 2008 catch data are provisional.FIGURA B-1. Capturas totales (capturas retenidas más descartes) de las pesquerías de cerco, y capturas retenidas de las pesqueríascañera y palangreras, de atún aleta amarilla en el Océano Pacífico oriental, 1975-2008. Las capturas cerqueras están ajustadas a laestimación de la composición por especie obtenida del muestreo de las capturas. Los datos de captura de 2008 son provisionales.65
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COVER PHOTOGRAPH BY WAYNE PERRYMANF
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3FISHERY STATUS REPORT 7TUNAS AND B
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5INFORME DE LA SITUACIÓN DE LA PES
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7A. THE FISHERY FOR TUNAS AND BILLF
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10fisheries, and have been reported
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12line vessels.The estimated size c
Page 16 and 17: 14Figure 2. Carrying capacity, in c
Page 18 and 19: 16FIGURE A-2a. Average annual distr
Page 20 and 21: 18.FIGURE A-4. Distributions of the
Page 22 and 23: 20FIGURE A-6a. Estimated size compo
Page 28 and 29: 26FIGURE A-9. Estimated catches of
Page 30 and 31: 28FIGURE A-11. Estimated size compo
Page 32 and 33: 30TABLE A-2a. Estimated retained ca
Page 34 and 35: 32TABLE A-2a. (continued)TABLA A-2a
Page 36 and 37: 34TABLE A-2b. (continued)TABLA A-2b
Page 38 and 39: 36TABLE A-3a. Catches of yellowfin
Page 40 and 41: 381TABLE A-3c. Catches of skipjack
Page 42 and 43: 40TABLE A-3e. Annual catches of big
Page 44 and 45: 42TABLE A-4b. Preliminary estimates
Page 46 and 47: 44TABLE A-6a. Annual retained catch
Page 48 and 49: 46TABLE A-7. Estimated numbers of s
Page 50 and 51: 48TABLE A-8. Types of floating obje
Page 52 and 53: 50TABLE A-10. Numbers and well volu
Page 54 and 55: 52TABLE A-11b. Estimates of the num
Page 56 and 57: 54A. LA PESQUERÍA DE ATUNES Y PECE
Page 58 and 59: 56En la Tabla A-2a se presentan las
Page 60 and 61: 581.3. Composición por tamaño de
Page 62 and 63: 601.5. Descargas de atunes y bonito
Page 64 and 65: 62bodega en el mar (VEM), en miles
Page 68 and 69: 66FIGURE B-2. Estimated recruitment
Page 70 and 71: 68FIGURE B-4. Spawning biomass traj
Page 72 and 73: 70FIGURE B-6. Catches of yellowfin
Page 74 and 75: 72FIGURE B-8. Phase plot of the tim
Page 76 and 77: 74TABLE B-1. Estimates of the MSY o
Page 78 and 79: 76Es importante señalar que la cur
Page 80 and 81: 78FIGURE C-1. Total catches (retain
Page 82 and 83: 80C. ATÚN BARRILETESe ha usado un
Page 84 and 85: 82fishing mortality are expected to
Page 86 and 87: 84FIGURE D-3. Average annual fishin
Page 88 and 89: 86FIGURE D-5. Trajectory of the spa
Page 90 and 91: 88FIGURE D-7. Catches for 1975-2008
Page 92 and 93: 90FIGURE D-9. Phase plot of the tim
Page 94 and 95: 92D. ATÚN PATUDOEn la presente eva
Page 96 and 97: 946. Los resultados son más pesimi
Page 98 and 99: 96FIGURE E-1. Retained catches of P
Page 100 and 101: 98F. ALBACORE TUNAThere are two sto
Page 102 and 103: 100300 000250 000200 000t150 000100
Page 104 and 105: 102fue aproximadamente 0.75, nivel
Page 106 and 107: 104FIGURE G-1. Retained catches of
Page 108 and 109: 106H. BLUE MARLINThe best knowledge
Page 110 and 111: 108H. MARLÍN AZULLa mejor informac
Page 112 and 113: 110FIGURE I-1. Retained catches of
Page 114 and 115: 112J. ECOSYSTEM CONSIDERATIONS1. In
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114have been identified (by presenc
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116Some marine mammals are adversel
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118tors of stress, and removing liv
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120Knowledge of the trophic ecology
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1226. AGGREGATE INDICATORSRecogniti
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124b. The incidental mortalities of
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126FIGURE J-1. Simplified food-web
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128FIGURE J-4. Trophic level estima
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130cual no es incluida en los anál
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132Especie y poblaciónMortalidad i
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1342.7. Tiburones y otros peces gra
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136condición de la población del
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1387‰ con respecto a la línea de
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140entre índices de asociación de
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142b. En junio de 2003, la CIAT ado
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