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What is "100?"

Photographer: Sterling Zumbrunn

The Ocean Health Index is all about the scores.

Higher or lower scores show what is working and what needs attention. Ocean health is measured on a scale of zero to a hundred, with a hundred meaning that all goals are being reached sustainably. To do that, the benefits provided by each goal are evaluated in the relation to a carefully selected, goal-specific reference point.

The Ocean Health Index, just related in Nature (August 2012), relies on four ways of determining a reference point:

 * The reference point may be a point on a production equation that describes output in relation to inputs – for example, fisheries catch related to fishing intensity. This is how the reference points for fisheries and Artisanal Fisheries Opportunities were chosen.

 * The reference point can also be a comparison with a value (or average value) at a specific date or period in the past. This is how the reference points for Carbon Storage and Coastal Protection were selected.

 * The third method used was a comparison with other places or countries- a spatial comparison. The goals for Mariculture and for Tourism and Recreation used this type of reference point.

 * The fourth method was using a benchmark previously established by treaty, law or other agreement. This is how the reference point for the Iconic Species sub-goal for Sense of Place was selected.

In all cases, reference points were chosen to be ‘SMART’ – Specific, Measurable, Ambitious, Realistic, and Timebound.

For more on the methodology behind the reference points, take a look at "Sea Sick? Setting targets to assess ocean health and ecosystem services,” authored by Dr. Jameal Samhouri, a Research Fishery Biologist at NOAA’s Northwest Fisheries Science Center, and colleagues from the Ocean Health Index’s science team.

“What makes any indicator meaningful is the benchmark against which it is judged,” says Samhouri. “Whether it is a vital rate like your blood pressure, the time you run in a race, or the Dow Jones Industrial Average, you need to know how the value you see today compares to the value you want it to be or what it was in the past. The Ocean Health Index relies on a simple and practical set of benchmarks to ensure it is meaningful.”

The paper was published in May 2012 in Ecosphere