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Resumen:
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A total of 19,471 bigeye tuna were captured, tagged, and released in the equatorial eastern Pacific Ocean, during March to May of 2000 and 2002-2005. Of the 19,148 dart tags and 323 geolocating archival tags deployed, 8,263 (43.2%) and 163 (50.5%), respectively, were returned. Times at liberty ranged from 1.7 to 2,291 d ( x = 169, SE = 1.8). Linear displacements, from release to recapture positions, ranged from 0 to 7093 km ( x = 560, SE = 7.8). Of the 6,692 bigeye at liberty for 30 d or longer, 95% were recaptured within 1,894 km of their release positions. The primary directional sector of the linear displacements was 255° to 300°, comprising 43.5% of the observations. An unscented Kalman filter (UKF) model with sea-surface temperature measurements integrated was used to process 98 archival tag data sets from bigeye at liberty for 30 d or longer, in order to obtain improved estimates of geographic positions, most probable tracks, and movement parameters. The median parameter estimates from the UKF model for errors in longitude (σx) and latitude (σy) were 0.27° and 2.34°, for directed movements (u and v) were 1.25 nm/d and 0.35 nm/d, and for dispersive movement (D) was 465 nm2 /d. The 95% and 50% utilization distributions, based on 11,585 positions for the combined 98 bigeye archival tag data sets, were 1,326,325 km2 and 60,667 km2, respectively, and were centered between about 3°N and 5°S and 90°W and 105°W. Based on the archival tag data there are differences in the spatial patterns of movements by year of deployment and fish age or size. These data clearly indicate that bigeye exhibit restricted movements, with regional fidelity to this area of high biological productivity. The tagging data from this study and others also indicate the very low level of mixing between the eastern and western Pacific, but do confirm there is some mixing of fish between these areas and almost certainly mixing within and between overlapping areas defined by 2,000 km radii across the Pacific.
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