Reconstructing transoceanic migration patterns of Pacific bluefin tuna using a chemical tracer toolbox

Authors

  • Daniel J. Madigan,

    1. Hopkins Marine Station of Stanford University, 120 Oceanview Boulevard, Pacific Grove, California 93950 USA
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    • Present address: School of Marine and Atmospheric Sciences, Stony Brook University, 105 Dana Hall, Stony Brook, New York 11794-5000 USA. E-mail: daniel.madigan@stonybrook.edu

  • Zofia Baumann,

    1. School of Marine and Atmospheric Sciences, Stony Brook University, 105 Dana Hall, Stony Brook, New York 11794-5000 USA
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  • Aaron B. Carlisle,

    1. Hopkins Marine Station of Stanford University, 120 Oceanview Boulevard, Pacific Grove, California 93950 USA
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  • Danielle K. Hoen,

    1. Global Environmental Sciences, University of Hawaii, 1000 Pope Road Marine Sciences Building 205, Honolulu, Hawaii 96822 USA
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    • Present address: Department of Oceanography, University of Hawaii, Honolulu, 1000 Pope Road Marine Sciences Building 205, Hawaii 96822 USA.

  • Brian N. Popp,

    1. Department of Geology and Geophysics, University of Hawaii, 1680 East-West Road POST Building 701, Honolulu, Hawaii 96822 USA
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  • Heidi Dewar,

    1. Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 8901 La Jolla Shores Drive, La Jolla, California 92037 USA
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  • Owyn E. Snodgrass,

    1. Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 8901 La Jolla Shores Drive, La Jolla, California 92037 USA
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  • Barbara A. Block,

    1. Hopkins Marine Station of Stanford University, 120 Oceanview Boulevard, Pacific Grove, California 93950 USA
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  • Nicholas S. Fisher

    1. School of Marine and Atmospheric Sciences, Stony Brook University, 105 Dana Hall, Stony Brook, New York 11794-5000 USA
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  • Corresponding Editor: J. R. Rooker.

Abstract

Large pelagic predators play important roles in oceanic ecosystems, and may migrate vast distances to utilize resources in different marine ecoregions. Understanding movement patterns of migratory marine animals is critical for effective management, but often challenging, due to the cryptic habitat of pelagic migrators and the difficulty of assessing past movements. Chemical tracers can partially circumvent these challenges by reconstructing recent migration patterns. Pacific bluefin tuna (Thunnus orientalis; PBFT) inhabit the western and eastern Pacific Ocean, and are in steep decline due to overfishing. Understanding age-specific eastward transpacific migration patterns can improve management practices, but these migratory dynamics remain largely unquantified. Here, we combine a Fukushima-derived radiotracer (134Cs) with bulk tissue and amino acid stable isotope analyses of PBFT to distinguish recent migrants from residents of the eastern Pacific Ocean. The proportion of recent migrants to residents decreased in older year classes, though the proportion of older PBFT that recently migrated across the Pacific was greater than previous estimates. This novel toolbox of biogeochemical tracers can be applied to any species that crosses the North Pacific Ocean.

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