Research ArticleECOLOGY

Atlantic Multidecadal Oscillations drive the basin-scale distribution of Atlantic bluefin tuna

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Science Advances  02 Jan 2019:
Vol. 5, no. 1, eaar6993
DOI: 10.1126/sciadv.aar6993
  • Fig. 1 Ensemble reconstructions of long-term fluctuations in Atlantic bluefin tuna abundance.

    (A and C) Historical records (black line) and predicted long-term fluctuations in abundance (averaged prediction as an orange line with 5 and 95% confidence intervals as gray shading) calculated from (A) 1634–1929 (preindustrial tuna fishery period) with no lag and (C) with a one-generation lag (16 years). (B and D) Mean relative influence [and associated SD (standard deviation)] of the four hydroclimatic variables used to reconstruct bluefin tuna abundance.

  • Fig. 2 Habitat-based reconstruction of Atlantic bluefin tuna abundance.

    Coefficient of linear correlation (r) and its associated probability (P) between historical records of Atlantic bluefin tuna abundance (from Fig. 1; black line) and long-term changes (1891–2011) in the species’ habitat suitability (orange line) reconstructed from the PCA computed on annual anomalies of probability of occurrence of bluefin tuna.

  • Fig. 3 AMO phases and spatiotemporal variability in habitat suitability and distribution of Atlantic bluefin tuna.

    (A and B) Anomalies of habitat suitability, reported occurrences (per 1° by 1° geographical cell; red dots), and mass centroids of occurrences (black dots) during (A) positive (1929–1962 and 1995 to present; nbins = 964) and (B) negative (1896–1928 and 1963–1994; nbins = 979) AMO phases. (C) Time series of mean anomalies (blue line) in the Nordic region [inset in (B)] from 1891 to 2011. Vertical dashed lines indicate abrupt changes in habitat suitability, and horizontal lines indicate the mean habitat suitability for each phase. The size of the tuna is proportional to its frequency of occurrence.

  • Fig. 4 Habitat suitability of Atlantic bluefin tuna when the Nordic fishery collapsed.

    Mean anomalies of probability of occurrence of Atlantic bluefin tuna before the collapse (1959–1961; left) and when the fishery collapsed (1962–1963; right).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/1/eaar6993/DC1

    Fig. S1. Summary of the two-step analysis conducted in this study.

    Fig. S2. Relationships between each hydroclimatic index and the abundance of Atlantic bluefin tuna from the BRT analysis.

    Fig. S3. Long-term changes in the Atlantic Multidecadal Oscillation and in the abundance of eastern Atlantic bluefin tuna.

    Fig. S4. Spatiotemporal variability in the habitat suitability of Atlantic bluefin tuna.

    Fig. S5. Decadal monthly anomalies of habitat suitability of Atlantic bluefin tuna in the NE Atlantic.

    Fig. S6. Thermal niche of Atlantic bluefin tuna.

    Table S1. Influence of tree complexity and bagging fraction on the performance of the BRT models.

    Table S2. Effects of different combinations of environmental variables and of different thresholds of occurrence on the performance of the NPPEN model applied on Atlantic bluefin tuna.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Summary of the two-step analysis conducted in this study.
    • Fig. S2. Relationships between each hydroclimatic index and the abundance of Atlantic bluefin tuna from the BRT analysis.
    • Fig. S3. Long-term changes in the Atlantic Multidecadal Oscillation and in the abundance of eastern Atlantic bluefin tuna.
    • Fig. S4. Spatiotemporal variability in the habitat suitability of Atlantic bluefin tuna.
    • Fig. S5. Decadal monthly anomalies of habitat suitability of Atlantic bluefin tuna in the NE Atlantic.
    • Fig. S6. Thermal niche of Atlantic bluefin tuna.
    • Table S1. Influence of tree complexity and bagging fraction on the performance of the BRT models.
    • Table S2. Effects of different combinations of environmental variables and of different thresholds of occurrence on the performance of the NPPEN model applied on Atlantic bluefin tuna.

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