An index to assess the health and benefits of the global ocean

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The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.

At a glance


  1. Conceptual framework for calculating the index.
    Figure 1: Conceptual framework for calculating the index.

    Each dimension (status, trend, pressures and resilience) is derived from a wide range of data. Dimensions combine to indicate the current status and likely future condition for each of ten goals (see equations in Methods Summary and equations (1) and (4) in Methods). Colour scheme is also used in Figs 36.

  2. Map of index and individual goal scores per country.
    Figure 2: Map of index and individual goal scores per country.

    All waters within 171 exclusive economic zones (EEZs), that is, up to 200 nautical miles, were assessed and are represented on the map. See Supplementary Table 24 for details and Supplementary Fig. 2 for sub-goal maps. NA, not available.

  3. Index scores (inside circle) and individual goal scores (coloured petals) for global area-weighted average of all countries and for several representative countries.
    Figure 3: Index scores (inside circle) and individual goal scores (coloured petals) for global area-weighted average of all countries and for several representative countries.

    The outer ring is the maximum possible score for each goal, and a goal’s score and weight (relative contribution) are represented by the petal’s length and width, respectively, except for ‘food provision’ sub-goals which are weighted by relative actual yield despite equal width of petals (see Supplementary Table 24 for per-country weights). All plots use equal weighting for all goals. Figures 36 use consistent goal-specific colour schemes. Grey indicates that a goal is not relevant to that reporting region.

  4. Global index scores with goals weighted unequally based on four different potential value sets.
    Figure 4: Global index scores with goals weighted unequally based on four different potential value sets.

    Value sets are illustrative rather than prescriptive; labels for the value sets are approximations and should not be interpreted literally. See Supplementary Table 4 for weights used in each value set.

  5. Distribution of scores across countries for the index and each goal.
    Figure 5: Distribution of scores across countries for the index and each goal.

    Histogram plots are smoothed across five point bins; dashed vertical line is the arithmetic mean and so differs from the area-weighted mean in other figures. Note different scales on y axes.

  6. Box and whisker plots for status, likely future state, pressures, resilience (light grey area), and trend (dark grey area) for country-level scores for each goal and sub-goal.
    Figure 6: Box and whisker plots for status, likely future state, pressures, resilience (light grey area), and trend (dark grey area) for country-level scores for each goal and sub-goal.

    Histograms are shown separately for each sub-goal. Note the different scale for trend (right y axis).


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Author information


  1. National Center for Ecological Analysis and Synthesis, 735 State St Suite 300, Santa Barbara, California 93101, USA

    • Benjamin S. Halpern,
    • Catherine Longo,
    • Darren Hardy,
    • Jennifer O’Leary,
    • Marla Ranelletti &
    • Courtney Scarborough
  2. Center for Marine Assessment and Planning, University of California, Santa Barbara, California 93106, USA

    • Benjamin S. Halpern
  3. COMPASS, Oregon State University, Department of Zoology, Corvallis, Oregon 97331-2914, USA

    • Karen L. McLeod
  4. Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard East, Seattle, Washington 98112, USA

    • Jameal F. Samhouri
  5. Conservation International, 2011 Crystal Drive, Arlington, Virginia 22202, USA

    • Steven K. Katona,
    • Andrew A. Rosenberg,
    • Elizabeth R. Selig,
    • Leah Bunce Karrer &
    • Gregory S. Stone
  6. Sea Around Us Project, Fisheries Centre, University of British Columbia, Vancouver, British Colombia V6T 1Z4, Canada

    • Kristin Kleisner,
    • Daniel Pauly,
    • U. Rashid Sumaila &
    • Dirk Zeller
  7. Marine Science Institute, University of California, Santa Barbara, California 93106, USA

    • Sarah E. Lester
  8. Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106, USA

    • Sarah E. Lester,
    • Steven D. Gaines &
    • Kelsey I. Jacobsen
  9. Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, USA

    • Benjamin D. Best
  10. Center for Biodiversity and Conservation, American Museum of Natural History, New York, New York 10024, USA

    • Daniel R. Brumbaugh
  11. Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA

    • F. Stuart Chapin
  12. Center for Ocean Solutions and Hopkins Marine Station, Stanford University, Monterey, California 93940, USA

    • Larry B. Crowder
  13. College of Marine Science, University of South Florida, St Petersburg, Florida 33705, USA

    • Kendra L. Daly
  14. Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA

    • Scott C. Doney
  15. Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, California 93106, USA

    • Cristiane Elfes
  16. IUCN Global Species Programme/Conservation International, Biodiversity Assessment Unit, 2011 Crystal Drive, Arlington, Virginia 22202, USA

    • Cristiane Elfes
  17. Northeast Fisheries Science Center, Woods Hole, Massachusetts 02453, USA

    • Michael J. Fogarty
  18. Department of Ecology and Evolutionary Biology & Center for Environmental Studies, Box 1943, Brown University, Providence, Rhode Island 02912, USA

    • Heather M. Leslie
  19. COMPASS, University of Washington, School of Aquatic and Fisheries Sciences, Seattle, Washington 98195, USA

    • Elizabeth Neeley
  20. Department of Applied Economics, University of Minnesota, 1994 Buford Avenue, St Paul, Minnesota 55108, USA

    • Stephen Polasky
  21. New England Aquarium, Central Wharf, Boston, Massachusetts 02110, USA

    • Bud Ris
  22. Department of Geography, Rutgers University, 54 Joyce Kilmer Drive, Piscataway, New Jersey 08854, USA

    • Kevin St Martin


B.S.H., C.L., K.L.M., J.F.S., S.K.K., S.E.L., A.A.R., D.R.B., F.S.C., L.B.C., K.L.D., S.C.D., M.J.F., S.D.G., L.B.K., H.M.L., S.P., K.S.M., B.R. and G.S.S. conceived and planned the study. B.S.H., C.L., D.H., S.E.L., J.O., M.R., C.S., E.R.S., B.D.B., C.E., K.I.J., D.P., U.R.S. and D.Z. aided with data collection and database development. B.S.H., C.L., D.H., K.L.M., J.F.S., S.K.K., K.K., S.E.L., A.A.R., C.S., E.R.S., F.S.C., K.L.D., S.C.D., C.E., M.J.F., S.D.G., L.B.K., H.M.L., U.R.S. and D.Z. helped with data interpretation. B.S.H., C.L., D.H., K.L.M., J.F.S., S.K.K., K.K., S.E.L., J.O., M.R., A.A.R., C.S., E.R.S., B.D.B., D.R.B., S.C.D., M.J.F., S.D.G. and S.P. developed index and goal-specific models. B.S.H., C.L., D.H., A.A.R., S.C.D. and M.J.F. conducted analyses. B.S.H., C.L., K.L.M., J.F.S., B.D.B. and E.N. developed the figures. B.S.H. drafted the initial manuscript and provided overall project management. All authors edited the manuscript.

Competing financial interests

The authors declare no competing financial interests.

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Supplementary information

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  1. Supplementary Information (3.7M)

    This file contains Supplementary Text and Data, Supplementary Tables 1-33, Supplementary Figures 1-9 and Supplementary References. The Supplementary Methods provide detailed descriptions of the general framework for calculating the index, goal-specific methodologies, and details about each data layer used. The Supplementary Results present sensitivity analyses on each of the key parameters in the index model. Supplementary Tables 1-33 give comprehensive information on data used and complete results for each country for each goal and sub-goal, and for certain sensitivity analyses. Supplementary Figures 1-9 include visualizations of how the index is calculated maps for sub-goal results, and a variety of outputs from correlation and sensitivity analyses. This file was replaced 23 January 2013.


  1. Report this comment #49169

    Kevin Matthews said:

    This is a very interesting study – one that deserves a critical reading, beyond the nice reaction of environmental support because of the (apparent) topic. As presented, it appears to be extremely problematic.

    The paper says, "We developed and implemented a systematic approach for measuring overall condition of marine ecosystems that treats nature and people as integrated parts of a healthy system."

    In other words, within the "ocean health" score, providing costal jobs (and recreation, etc.) is weighed alongside things like the extinction of fish species.

    I am skeptical that the all-in-one number score actually tells us what we need to know – or what the public, and policy makers, are likely to think they are getting in a measure of "ocean health."

    In fact, when one looks at the "ten goals" stated in the paper to underly the scoring system, they really don't add up to what I would call "ocean health." Maybe more like 'ocean health, services to humanity, and contributions to human satisfaction."

    The top-line scoring could have been designed, as an alternative example, to give three components along the lines of triple bottom line analysis. That makes potential "trade offs" between economic and environmental factors transparent, unlike an all-in-one score.

    At a time when global ecosystems are on the verge of collapse due to overexploitation to meet human demands...
    "Approaching a State Shift in Earth's Biosphere"

    ...we really need to keep the ecological realities and the human benefits clearly separated.

    Instead, confusion generated by this paper is already percolating through the general media, where it is generally taken as a ecological assessment – with broadly positive results – rather than the ecological, social, and economic conflation that it is.

    The scoring system appears to involve a myriad of value judgments, logical recursions, trend clipping, subjective equalities, and indeterminate normalizations. The idea that one all-encompassing score will provide transparency and reduce subjectivity is flawed at its root.

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