FAQ

What Is The
Ocean Health Index?

This Index is the first comprehensive global measurement of ocean health that includes people as part of the ocean ecosystem.

It scientifically compares and combines all dimensions of ocean health – biological, physical, economic and social, in order to generate an objective and accurate snapshot of the health of the ocean controlled by every coastal country.


What is a healthy ocean?

A healthy ocean sustainably delivers a range of benefits to people now and in the future.

Humans and our activities are part of the ocean, and the human-ocean system is healthier if it delivers the most benefits for us that it can without jeopardizing the future health or function of the web of life that the ocean contains.

The Index assesses the ocean based on 10 widely-held public goals for a healthy ocean. They are:
  • Food Provision
  • Artisanal Fishing Opportunities
  • Natural Products
  • Carbon Storage
  • Coastal Protection
  • Sense of Place
  • Coastal Livelihoods & Economies
  • Tourism & Recreation
  • Clean Waters
  • Biodiversity

What's the difference between a goal and a benefit?

Each goal expresses a broad, long-term purpose, optimizing a sustainable flow of benefits to people.  Benefits are the specific and measurable goods (e.g. fish), services (e.g. coastal protection) or cultural values (e.g. sense of place) that the ocean provides.

How were the goals selected?

Participating scientists, economists and sociologists reviewed existing studies of what people want and expect from the ocean, then grouped them into the ten categories called ‘goals’.

Are some goals more important than others?

They may be for some countries, but at the global level the Index weights all goals evenly. Nations could re-value goals as part of a country-level Ocean Health Index study.

Why is a healthy ocean important?

Oceans are our most valuable asset. They contain 99% of the space occupied by life on our planet, hold 97% of the planet's water, produce more than half of the oxygen in the atmosphere, and regulate the earth’s climate.

More than 40% percent of the world’s population lives within 100 km of the coast, and ocean-based businesses contribute more than 38 million jobs and global ocean economic activity estimated by UNESCO to be worth between $3-6 trillion annually.

Today more than one billion people depend on fish for their basic protein. By 2050, our human population will require nearly twice as much food as it does today as a result of population increase to 9 billion and (hoped-for) increase in prosperity and growth of the middle class. More food will be required from the oceans to help meet that growing demand.

The sheer number of people who use and depend on the ocean, coupled with unwise practices we adopt, produce problems such as overharvesting of resources, reduction in biodiversity, degradation of marine habitats and potential extinction of species, among others. We jeopardize the very ecosystems on which our well-being (and perhaps survival) depends.

Oceans nourish us, provide livelihoods and sustain life on earth, but we no longer can take ocean benefits for granted.  The Ocean Health Index provides a useful framework and instrument to help us manage our oceans more thoughtfully and sustainably.

What is different about the
Ocean Health Index?

Other indices track various economic, social and environmental sectors, but this is the first index to track ocean health.

Recognizing that people are now part of the ocean ecosystem, this Index evaluates how well the ocean provides 10 key benefits to people and how well we protect its ability to do so in the future.  It scores how well coastal countries and their marine territories optimize their potential ocean benefits.

It is the first ocean assessment tool that scientifically compares and combines key elements from all dimensions of the ocean’s health – biological, physical, economic and social--- so that leaders, managers and the public can promote an increasingly beneficial future for all ocean life, including us.

By integrating information from many different disciplines and sectors the Index represents a significant advance over conventional single-sector approaches to assessing ocean condition.

How does the
Ocean Health Index relate to other indices?

In 1969, Buckminster Fuller said “Now there is one outstandingly important fact regarding Spaceship Earth and that is that no instruction book came with it.” The Ocean Health Index and other available indices are all contributions to developing that manual. They are dashboard instruments to help us monitor planetary condition in a more responsible manner than has been possible in past.

The Index draws on data from a number of existing indices, including the Consumer Price Index, Global Competitive Index, Human Development Index, Mariculture Sustainability Index, Tourism and Travel Competitive Index, World Governance Indicators as well as information from treaties and international projects such as the Convention on Biological Diversity, Convention on International Trade in Endangered Species and IUCN Red List.

What is the primary objective of the Index?

The purpose of the Index is to encourage decisions that create a healthier ocean and to track progress toward that goal.

By communicating the state of the world’s ocean, the Index aims to build awareness and catalyze decision makers to develop and implement more effective policies that promote ocean health.

Scores for the Index’s ten goals provide leaders with information needed to create a more sustainable human-ocean ecosystem.

Index results and information help identify and quantify the benefits and tradeoffs of each action, enabling leaders and the public to evaluate actions more clearly, broadly and holistically.

What does the Index tell us that we don't already know?

The Index allows us to combine different types of data and values to compare how well each country--- and the world as a whole--- is achieving a portfolio of key goals. Evaluating the performance of the entire portfolio provides more information than evaluating each goal separately.

Historically, information about livelihoods, water quality, biodiversity, food production and other subjects have been considered separately. The Index analyzes them together so people can see how they interact and how we are doing overall in a comparable fashion.

The Index allows countries to compare their progress to one another and to the global average in a way not possible with current ocean assessment tools.

Results can inform countries about how various actions could improve their future Index scores.

Is the
Ocean Health Index at odds with conservation because of its focus on human benefits?

The Ocean Health Index is both people-centric and nature-centric. Several goals are explicitly about preserving nature and all goals must be pursued sustainably to achieve a high score.

The Index’s focus on benefits to people and human well-being is strategic. When well-being improves, people can devote more attention and resources to social and environmental maintenance and improvement. When well-being decreases, people must do anything they can to survive; both social and natural environments will suffer.

Conservation in today’s world can only be effective if it acknowledges and encourages a beneficial, integrated relationship between people and nature and contributes to building healthy sustainable societies.

Who collaborated on the
Ocean Health Index?

The Index is a scientific effort developed by the contributions of more than 65 experts on marine science, economics and sociology from many leading universities, laboratories and government agencies.

Principal organizers of the Index include the National Center for Ecological Analysis and the Synthesis at the University of California, Santa Barbara; the University of British Columbia’s Sea Around Us project, Conservation International, the National Geographic Society and the New England Aquarium.

How will the
Ocean Health Index benefit a country?

Results and information provided by the Index can help countries prioritize and make the case for actions that could improve Index scores.

What are the primary sources of financing for the
Ocean Health Index?

Beau and Heather Wrigley generously provided the founding grant. Pacific Life Foundation is the founding presenting sponsor. Thomas W. Haas Fund of the New Hampshire Charitable Foundation, the Oak Foundation, Akiko Shiraki Dynner Fund for Ocean Exploration and Conservation, Darden Restaurants Inc. Foundation, Conservation International, New England Aquarium, and National Geographic provided financial and/or in-kind support. The National Center for Ecological Analysis and Synthesis supported the Ecosystem Health Working Group as part of the Science of Ecosystem-Based Management project funded by the David and Lucile Packard Foundation. Individual collaborators received additional support from NSF, NASA, NOAA, and Stanford University’s Center for Ocean Solutions and the Sea Around Us Project, with support from the Pew Charitable Trusts.

How many countries were assessed?  How were the EEZ boundaries defined?

The 2013 Index evaluated all existing Exclusive Economic Zones (EEZs) controlled by all 151 of the world’s coastal countries.   This produced scores for 221 EEZs, a big improvement over the 2012 Index, which had to lump some EEZs together owing to lack of data, producing scores for only 171 reporting regions.   As one example, in 2012 the Cook Islands were lumped with New Zealand, Niue and Tokelau, but all are separated out and have their own scores in the 2013 study.

The 2013 Index used the EEZ boundaries defined by Marine Regions.

Where do the data come from?

The Index uses more than one hundred global databases and strives to use the most current data available.  It is updated and improved annually.

How is a goal scored?

The 2013 Index evaluates ocean health for 221 reporting areas---Exclusive Economic Zones (EEZs) extending 200 nautical miles seaward from the shore---that are under the jurisdiction of the world’s 151 coastal countries.

Each reporting area is evaluated for 10 goals.  Each goal scores from 0 to 100, where a score of 100 means that optimal benefits are being fully realized for that goal.

The present Status of each goal is found by comparing the amount of the measured benefit (such as extent of carbon-storing habitats or biomass of fish stocks) with a goal-specific sustainable reference point. The reference point may be a target value at some time in the past, comparison with some other location (such as the best performing country), a target previously established by a treaty or other agreement, or---best of all---a target determined by an accepted input-output equation (also called a production function).

The present Status forms half of the score.  The other half, Likely Future Status, is based on three things: the Trend (average rate of change for Status during the most recent five years; the cumulative Pressures that will harm future benefits; and the cumulative Resilience actions (e.g. treaties, laws, enforcement, habitat protection) that can reduce pressures and maintain or raise future benefits. If a goal has sub-goals, the goal score equals the average of sub-goal scores.   The only exception is Food Production, where the goal score is a yield-weighted average of the two sub-goal scores.

What drives goal scores?

Present Status makes up 50% of each goal score, Trend makes up 33% and the balance between Pressures and Resilience makes up 16%.  Thus 83% of a goal score reflects how sustainably a goal’s benefits have actually been achieved during the recent five years.  Pressures and Resilience are ultimately important for scores, but are weighted lower because we can only approximate their effects. Individual pressures are ranked for their importance to different goals. Resilience actions are the only ways we can change a score, because they can reduce pressures, protect ocean habitats and species, improve Status and optimize benefits to people.  Without effective Resilience, negative trends will continue.  New resilience measures improve scores gradually, because Trend must gradually shed five years of pre-resilience Status values; however each new year should bring more rapid improvement.

How is a country's score calculated?

A country’s score is the average of its goal scores. Goals not applicable to a country are not scored or averaged. If a country is bordered by several EEZs, its score is the area-weighted average of those EEZs. Any remotely located EEZs are scored and reported separately. Scores are calculated for 221 EEZs, representing all of the world’s 151 coastal countries and their territorial holdings.

How is the global score calculated?

The global Ocean Health Index score is the area-weighted average of scores for all 221 EEZs.  

The global score could be calculated in two ways, but it makes a difference and one way is preferable. Here is the method used by the Index. Scores for all ten goals are averaged within each region to give the region’s overall score. Then all regions’ overall scores are averaged, weighted by the respective areas of their regions, so that larger regions play a more important role in determining the global score because they represent a larger portion of the world’s oceans.  A less satisfactory method would be to first calculate the average score for each goal across all regions, again weighting by each region’s size, and then take the mean of all 10 average goal scores.

The first and preferred method best captures the core principle that ocean health is the result of interactions among the ten goals in a particular location. For example, low scores in Biodiversity might be associated often with high scores in Natural Products, due to a tradeoff between the two goals. If the goal scores are averaged within each country, the score will reflect this interaction by assigning similar scores to places that do well in one or the other goal (all else being equal). The second, goal-based method disarticulates goals from one another, implicitly ignoring such interactions. For example, if in most cases Natural Products scores well, its global average will be very high, so when averaged with the other goals, it may produce an excessively optimistic overall global score because the tradeoff with Biodiversity is ignored.

What does the score mean?

All scores range from 0 to 100. 
  • ‘100’ means that the evaluated system has achieved its defined target (reference point), is sustainably delivering all of the specified benefits that it can and is likely to continue doing so in the near future.  
  • ‘0’ means that global data were available, but that the country either did not achieve any of the available benefits or that the benefits it did obtain were gained in a manner that was not sustainable.  
  • Intermediate scores mean that the optimal benefit is not being obtained and/or is not being obtained in a sustainable way.  The higher the score, the closer a country is to obtaining optimal sustainable benefits.

Does the
Ocean Health Index explain why a score is high or low?

Index scores are derived from approximately one hundred databases. Each database measures one or more specific factors, for example sea level rise, marine and terrestrial protected areas, coastal human population, the risk of extinction for marine species or iconic species, or the annual amount of revenue provided by industries in the marine sector. 

Sometimes the database contains information that explains a score.  For example, we can see that a large increase in protected areas caused South Georgia and the South Sandwich Islands’ score for the Lasting Special Places sub-goal to increase 95 points from 2012 to 2013. The database does not specify ­which areas were added, but exploration elsewhere reveals that a new 1 million square kilometer marine protected area was designated in 2012. 

On the other hand, some data layers do not contain information that explains their values or variation and those seeking such explanations must consult other sources. For example, to understand the underlying reasons why species were assigned the particular categorical extinction risks shown in the database, a reader would need to consult the narrative species accounts that form the basis of the International Union for Conservation of Nature “Red List.”  Similarly, to explain underlying causes of a nation’s variations in the amount of marine sector revenue, one would need to explore other sources of information about that country as well as the global economic background. Was there a global economic slowdown? Did environmental conditions affect the mariculture or tourism industries?  Was there political unrest or other disturbance?  Such information is beyond the scope of the Index. 

Though it may seem unsatisfying that the Index cannot provide all the answers we want, seeking them by digging deeper into its underlying databases (available online) and beyond will enrich anyone’s knowledge about the ocean and the world.

Does the score tell the condition of the ocean right now?

The Ocean Health Index is not a snapshot of ocean health in the year it is published, but instead reflects conditions several years earlier.  While some data, such as those monitored by satellite, are updated daily or monthly, other data collected by hand often requires several years to gather and assemble into a database refined enough for public use. The Index relies on the most recent data available at global scales (that is, for all countries). Data for different components of the index come from different years, many of which are not current for the newest publication year. For example, several years from now, as information gathered in 2013 enters the data stream, the score will more closely resemble what ocean conditions are today----but it will still lag what ocean conditions are in that future year.

Is it possible to score 100?

The maximum score of 100 is surely achievable for individual goals.  Country scores of 100 may be possible, but no country is close yet, though several remote territories are. Some countries may underuse ocean benefits such as food or tourism to protect resources against future uncertainty, thereby producing a score less than 100 in the current calculation. Negative interactions between goals (and perhaps between countries) could occur. For example, development that increased Tourism & Recreation could compromise coastal habitats, decreasing scores in Carbon Storage, Coastal Protection, Clean Water, Biodiversity or Food Provision. Maximizing benefits from extractive goals such as Food Provision or Natural Products could decrease benefits from other goals. On the other hand, high scores for Clean Water, Biodiversity, Coastal Protection, Sense of Place and Carbon Storage could improve the flow of benefits from other goals.  Without detailed quantitative understanding of such tradeoffs and interactions, it isn’t possible to say whether a country or global score of 100 is theoretically possible, but we aren’t really close enough to worry about that yet.

How were reference points determined?

The status of each goal is evaluated with regard to a goal-specific reference point.

Reference points must be chosen very carefully in order to provide useful and reliable information. There are four different ways to determine a reference point, depending on what you're trying to measure. They are: 1) a production equation (functional relationship) that describes output in relation to all inputs, e.g. fisheries catch related to fishing intensity; 2) temporal comparisons (e.g., a value at a specified date in the past or a rolling 3- or 5- year average), 3) spatial comparison (e.g. comparison with another country or region and 4) an established benchmarks (e.g. zero pollution or ‘all species at ‘least concern’ status for risk of extinction). Functional relationships are the gold standard, but data availability and limits to scientific understanding often require spatial or temporal comparisons. When functional relationships are not available for use, SMART (Specific, Measurable, Ambitious, Realistic, and Time-bound) reference points should be selected that are appropriate for the management goal.

How were the 10 goals of the Index selected?

Experts in marine science, economics and social science selected the goals after a thorough review of the existing literature containing information on what people expect from the ocean. They also reviewed the literature describing the pressures currently affecting ocean species, habitats and ecosystems and recommendations reported by major international conferences or included in international treaties or national policy frameworks regarding how to mitigate those pressures. They were able to group the various human expectations into 10 categories and frame them as goals. The goals are closely related to or in support of those used in international efforts such as the UN Millennium Development Goals, Convention on Biological Diversity and others.

How can such disparate goals be combined?

More than 100 data layers from different disciplines are used in the Index. Each dataset was converted to a unitless scale from 0 to 1.  Because units of measurement such as grams, tonnes, kilometers, dollars etc. drop out of that transformation, data of different kinds can be  combined and compared. Each goal is calculated using its own goal-specific reference point and mathematical model, but all results are expressed on a scale of 0 to 1, and then converted to 0 to 100 for ease of communication. Since all goals are scored in the same manner, scores can easily be combined to provide average overall scores for each country and scores for each country can be combined to provide the global Ocean Health Index score. Country scores are weighted by the areas of their EEZs when calculating the global Index score.

How are the goals weighted?

Different groups and countries probably value (weight) the importance of the 10 goals differently, but global information on such differences is not available. In the absence of that information the goals were weighted equally. We also explored several other hypothetical value sets, and they suggested that weights don't matter too much for the global score, but do make a difference in certain countries. Countries will be able to use the Ocean Health Index methods for detailed focal studies of the health of their waters. Such studies could use more recent or better quality local data than are available globally, and could incorporate country-specific goal weightings. The results of such studies would be useful for the country, but could not be compared with scores of other countries.

Are there any tradeoffs between goals?Could success in one goal cause other goals to decline?

Delivery of some goals may exert pressure on other goals. For example, increased fishing can produce more food, but may negatively impact biodiversity. If all fishing is done sustainably and governance measures are in place that can mitigate potential negative impacts, then these tradeoffs can be minimized, but not necessarily eliminated. An ideal balance between all goals is possible but difficult to quantify and achieve so tradeoffs are likely. Index scientists will investigate potential tradeoffs and how to quantify them during coming years.

What are the top threats to the health of the oceans?

Top threats to the health of the oceans are climate change, ocean acidification, overfishing, habitat destruction, pollution and the spread of invasive alien species.

Each threat differs in its immediate intensity, breadth of effects, geographic distribution and in other ways.

Some threats can be mitigated or prevented more easily than others. Slowing or stopping global climate change and ocean acidification is the most difficult challenge and will require decades of effort for improvement to be visible. In contrast, overfishing can be remedied at the country level within a decade.

The Ocean Health Index subdivides these threats and weighs their impacts differentially for different goals.

Each goal for each country has its own 'top threat' based on the intensity and weight of each threat for each goal.

Why do goals drop out for some locations?

In uninhabited places, most human-related goals - Food Provision, Livelihoods & Economies or Tourism & Recreation, for example- drop out because people don't live there and so the goal(s) is not relevant, not scored, and not counted against the overall score. In other cases, if a country has never been able to produce a goal, such as never having done mariculture or not having mangrove habitat, that goal or sub-goal is not scored and the country is not penalized.

For the Carbon Storage goal, why doesn't the Index include the whole ocean, instead of just a few coastal habitats?

Per unit area, coastal habitats (such as mangroves, sea grass and salt marshes) have the highest sequestration and storage rates of any habitat on earth, including terrestrial systems. Overall, coastal habitats store approximately 50% of all the carbon stored by the ocean.

Unlike open ocean areas, the carbon storage benefits of coastal habitats are immediately threatened, have large amounts of stored carbon that would rapidly be released with further habitat destruction, and are amenable to management, conservation, and restoration efforts.

Change over time in carbon storage by the open ocean is likely to take place slowly, making it an unsuitable indicator for the Index.

Why are the goals for Food Provision and Opportunities for Artisanal Fishing separated?

These goals measure different aspects of how people relate to fishing. The catch of fish made by artisanal (= small-scale) fisheries is captured in the Food Provision goal. Jobs, wages and income from both the Food Provision and Artisanal Fishing goals are captured in the Livelihoods & Economies goal. The purpose of the Artisanal Fishing Opportunity goal is to evaluate the opportunity for people to pursue this fishing in relation to their need to do so. The need for artisanal fishing opportunities is evaluated by the country’s per capita GDP, adjusted for local price purchasing power, under the assumption that people living in poorer nations have more need for such opportunity.

Why does the Biodiversity goal score so high when we know that species and habitats are declining?

The Ocean Health Index evaluates of species based on the categories for species extinction risk shown in the IUCN (International Union for the Conservation of Nature) Red List, the authoritative assessment of global extinction risks. Because IUCN assessments have been performed on relatively few species, data on some species that are threatened may not be available. In addition, it can take time before declines in species can be detected and reported by scientists. Although the current state of species looks relatively optimistic, nearly every country in the world has negative trends, so the likely future state of species looks much more pessimistic.

The Index evaluates the extent of habitats based on their extent in about 1980. One reason for the high score is the relatively recent reference point, so scores reflect changes that have taken place in only about three decades. The trend for habitats is negative for many places, so their high score is no basis for undue optimism. Many habitats were likely already significantly degraded by the ~1980 reference point date and restoring them to their state in earlier times does not seem possible now. However, restoring them to their ~1980 states is feasible and would significantly benefit many aspects of the human-ocean system.

A further reason why scores might seem too optimistic to some is that the Index rescaled biodiversity scores linearly, assuming that each additional species at risk or amount of habitat lost corresponds to an equivalent change in the Status score. In reality, people may consider initial losses of species or habitats much worse than when systems are already degraded or heavily at risk. For those with such a value system, Index scores may seem too optimistic.

Where is climate change measured in the Index?

Four different aspects of climate change -- increases in sea surface temperature (SST), sea level rise, ultraviolet radiation (UV), and ocean acidification -- are included as pressures to many goals in the Index, including Natural Products, Carbon Storage, Coastal Protection, Sense of Place, Livelihoods & Economies and Biodiversity. Mitigation of climate change through carbon storage is one of the ten goals.

What are the Worldwide Governance Indicators?

The Worldwide Governance Indicators (WGI) is a project of the World Bank and the Brookings Institution to assess the quality of governance in more than 213 countries worldwide. ‘Governance’ is the word used to describe what a government does and ‘governance effectiveness’ describes how well the government exercises its powers to create and enforce policies that benefit its citizens. Effective governance is essential to both successful development and maintaining environmental quality. "To achieve their environmental commitments and goals, States need strong legislative, political and judicial systems” (UNEP 2010). The Worldwide Governance Indicators comprise six dimensions of governance: Voice and Accountability, Political Stability and Absence of Violence, Government Effectiveness, Regulatory Quality, Rule of Law, Control of Corruption. The Ocean Health Index uses this information to indicate social pressures on various goals; and also to indicate social Resilience.

How far back in time do the data layers extend?

This varies greatly by data layer. Nearly all go back at least five years, many go back a decade or two, several go back many decades, and just a few extend back even further.

Can the
Ocean Health Index be updated and how often will that take place?

The global score will be recalculated every year. Not all datasets will be new every year, but any new data available will be used. Differences in the global score may not be visible from one year to the next, but should be visible over periods of perhaps 3 to 5 years. The score for an individual country could change more quickly as a result of resilience actions that it takes.

What spatial scale is appropriate for calculating an
Ocean Health Index score?

The Index can be calculated at any scale, but the smallest appropriate scale is determined by the quality of the data and the objectives of the study. Some changes to the individual goal models may be required at small scales owing to the types, detail and quality of data that are available.

When and how will High Seas areas be included in the Index?

The term ‘High Seas’ refers to waters beyond national jurisdiction, i.e. outside of all EEZs. The Ocean Health Index will assess those international waters, as well as waters around Antarctica, and include them in results for 2014. Scores for 2013 only evaluate waters out to 200 nm offshore from coastlines.  Many of the goals drop out for High Seas areas. For example, Tourism & Recreation might be small to non-existent in many such areas. It is more difficult to assess High Seas areas than coastal areas because of the lack of data. For example there is much less information on governance. Also, few areas are monitored.

Will the
Ocean Health Index really be able to detect meaningful signals of change given the many unpredictable changes ('background noise') in the human-ocean ecosystem?

If changes are frequent, large, random and not related to factors analyzed in the Ocean Health Index, the task will be much more difficult. However, if the Index has captured most of the factors causing current change and has accurately modeled many of their inter-relationships, then meaningful signals of change should be detectable. The scientific team has already conducted sensitivity analyses that demonstrate how relatively simple management changes can translate into meaningful, significant, and easily detectable changes in goal scores and even the overall Index score.

What amount of change is meaningful?

For a particular country, any change is meaningful, because the comparison is to its own previous scores.

For comparisons among countries, the distribution (variance) results for different countries indicates that changes in overall Index scores greater than 10 points will be statistically significant and meaningful. Differences greater than 5 points are probably meaningful but not statistically significant.

How will improving the scores for countries improve the quality of life for people?

Finding ways to make our relationship to the ocean more sustainable will give us a more reliable source of food, natural products, and coastal employment and revenue, for example. Doing so will also prevent decline or collapse of benefits in the future. All of this will become increasingly necessary as the world’s population approaches 9 billion during the coming three or four decades.

How can the
Ocean Health Index inform Ecosystem Based Management (EBM) and Coastal and Marine Spatial Planning (CMSP)?    

It can do this in many ways. The Index can serve as a measurement tool for assessing effectiveness of plans and progress towards goals; it can help identify potential tradeoffs among uses; it can guide monitoring and resource allocation decisions, and many more.

How do the 2013 scores relate to the scores published in 2012?

The Ocean Health Index science team constantly seeks to improve methods and update data used to compute scores. Doing so improves the quality and timeliness of assessments, but also poses the problem of how new scores can be compared with older ones. In order to assess actual differences in ocean health between 2012 and 2013, the 2012 scores originally published in Nature 2012 were recalculated using the improved methods used in 2013. Comparing the recalculated 2012 scores with the 2013 scores provides information about actual changes in each goal and region. On the other hand, comparing the scores published in 2012 to the recalculated scores for 2012---which we do not encourage as it can cause unnecessary confusion--- will highlight differences due to changes in methods and/or input data. Changes to the calculation of the Pressure layers were made that affect the calculation of all of the goals’ Likely Future State and overall Index score. 

All comparisons included on the Ocean Health Index Web site or discussed elsewhere focus exclusively on the recalculated 2012 scores and the 2013 scores. The scores obtained in 2012 with the previous methods and data and published in Nature 2012 are no longer discussed. All Index users are encouraged to follow that guideline. 

What changes were made to the
Ocean Health Index in 2013?

The changes made to Status and Trend are summarized below.

Goal/Sub-goal: Food Provision – Wild caught fisheries
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2010, 2011
Updated method: Yes
METHOD: The 2012 OHI used mMSY for wild-caught fisheries, based on a very simple model using reported catch. In 2013, the reference point is for the biomass (B) at sea of landed stocks to be within ±5% of the total biomass that can deliver maximum sustainable yield (BMSY).  This is based on a newly developed population model that is more complex (although still data poor) than the one from the previous year and better takes into account species-specific fishery dynamics. As before, countries are penalized for underharvest or (more severely) overharvest. 
DATA: FAO data that were spatially allocated by Sea Around Us in 2006 were projected forward using current FAO catch data

Goal/Sub-goal: Food Provision – Mariculture
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2010, 2011
Updated method: Yes
METHOD: In 2012, the mariculture reference point was tonnes of harvested product per km of coastline.  This decreased scores of countries with large stretches of uninhabited coastline. The 2013 reference point is harvested tonnes of product per coastal inhabitant (50 km of the coast).  This new version assumes that mariculture development scales with local demand, presence of infrastructures, and local workforce and uses coastal population density as a proxy for those factors.
DATA: updated FAO harvest data; new data-set: coastal population

Goal/Sub-goal: Food Provision
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated method: Yes
See explanations above.

Goal/Sub-goal: Artisanal Fishing Opportunities
Were data updated in 2012?  No
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated method: No
DATA: years of data added for Artisanal Fishing Need (i.e. income level adjusted by purchasing power)

Goal/Sub-goal: Natural Products
Were data updated in 2012?  No
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2008, 2009
Updated methods: Yes
METHOD: The sustainability coefficient for Fish Oil was updated (using the new fisheries method). Data analysis was improved to resolve mismatch between harvest and economic value data. 
DATA: Additional years of data were added for harvest of all products, exposure (that is based on harvest) and (for Corals and Ornamental Fish) risk.

Goal/Sub-goal: Coastal Protection
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated methods: No
DATA: The method to calculate habitat extent was changed, so the relative contribution of each habitat to the score might be different

Goal/Sub-goal: Carbon Storage
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 
Updated methods: No
DATA: The method to calculate habitat extent was changed, so the relative contribution of each habitat to the score might be different 

Goal/Sub-goal:Clean Waters
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2000-2005, 2006-2009
Updated methods: Yes
DATA: Additional years of data were available
METHOD: Some changes in data processing were needed to use the new data more effectively

Goal/Sub-goal: Livelihoods and Economies – Economies
Were data updated in 2012?  No
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): Various
Updated methods: No
DATA: Updated revenue data were used for the tourism sector, aquarium fish trade, and mariculture.

Goal/Sub-goal: Livelihood and Economies – Livelihoods
Were data updated in 2012?  No
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): Various
Updated methods: Yes
DATA: Updated marine wages data for all sectors. 
METHOD: The model was slightly simplified by removing one of the adjustment terms for wages

Goal/Sub-goal: Livelihoods and Economies
Were data updated in 2012?  No
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated methods: Yes
See explanation above

Goal/Sub-goal: Biodiversity - Habitats
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated methods: No
DATA: The method to calculate habitat extent was changed, so the relative contribution of each habitat to the score might be different. 

Goal/Sub-goal: Biodiversity – Species
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2000-2011
Updated methods: No
DATA: New risk assessment values were used in both 2012 and 2013 scores

Goal/Sub-goal: Biodiversity
Were data updated in 2012?
Were data updated in 2013?
Years used (2012, 2013 respectively):
Updated methods:
See explanation above.

Goal/Sub-goal: Sense of Place – Lasting Special Places
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2011-2012
Updated methods: No
DATA: More recent data on marine protected areas were used to calculate the 2012 and 2013 scores

Goal/Sub-goal: Sense of Place – Iconic Species
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively): 2000-2011
Updated methods: No
DATA: The list of species considered iconic remained the same, but new risk assessment values used in both 2012 and 2013 scores

Goal/Sub-goal: Sense of Place
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated methods:
See explanations above.

Goal/Sub-goal: Tourism and Recreation
Were data updated in 2012?  Yes
Were data updated in 2013?  Yes
Years used (2012, 2013 respectively):
Updated methods: Yes
DATA: different data were used, i.e. tourism employment instead of international arrivals. The tourism competitiveness index was maintained.
METHOD: The 2012 reference point was based on arrivals of international tourists with respect to local population size.  The 2013 OHI strives to capture both domestic and local tourism and uses the relative proportion of people directly employed in the coastal tourism industry relative to the total labor pool. As done previously, sustainability is estimated by the World Economic Forum’s Travel and Tourism Competitiveness Index.

How often will the Index make changes to methods such as occurred in 2013?

Changes may be needed on occasion if new kinds of data layers become available, new scientific advances occur or if a new goal must be developed. The Index is designed to be flexible and to have a long life. Some change in methods is likely to occur over time, but changes will be exceptional rather than routine. Changes will only be made for important reasons and with awareness that (1) they are a potential source of confusion for those using the Index and (2) they entail extra work and expense for the scientific team, because older results must be recalculated using the new methods to permit year-to-year comparisons.

Why did the global
Ocean Health Index score go from 60 to 65?

When recalculated 2012 scores and 2013 scores are compared, year-to-year scores for countries are generally reasonably close and the overall global scores are nearly identical. Thus ‘global ocean health’ did not change between years, but the original score calculation performed in 2012 and reported in Nature 2012 underestimated ocean health (60 instead of 65). This change is the result of all the modifications and improvements made, most importantly changes to goal models for Food Production and Tourism & Recreation. The bottom line is that ocean health is somewhat better than originally estimated, that the score of 65 is a more accurate estimate of current global health, but that ocean health overall has not changed between 2012 and 2013.

Why would a country's rank change between 2012 and 2013 even though its score stayed the same?

The first reason is that more regions were evaluated in 2013.  The 2012 Index evaluated 171 reporting regions. Most were separate EEZs, but in some cases the evaluated regions consisted of several EEZs lumped together owing to lack of data. For example, in 2012 the Cook Islands were lumped with New Zealand, Niue and Tokelau, but all were separated out in 2013. The 2013 Index separated out all EEZ regions, yielding 221 reporting regions. The inclusion of 50 additional EEZs necessarily caused changes in rankings. 

The second reason is that any score changes for other countries would necessarily reshuffle country rankings even for regions whose year-to-year score remained the same.

For these reasons it is not particularly informative to look at a country’s rank, but rather to focus on where its absolute score lies with respect to the range of scores observed across all other countries; and how its score differs from the scores of other countries of particular interest.

Why might a goal score for a country change a lot between 2012 and 2013?

At least four factors could contribute to a large change in goal scores.  They are:
  • Newly separated reporting areas: In 2012, in a number of cases, EEZs were lumped together for analysis because the individual units did not have enough data to be analyzed separately.  All EEZs were separated out and analyzed in 2013 as described in the online 2013 SOM.  With the increased resolution, data specific to each region (whenever possible) were used, so that the newly-defined regions could be expected to be assigned different scores.  
  • Goal model change: If the goal’s mathematical model changed between 2012 and 2013---as occurred for number of goals, particularly Food Production and Tourism & Recreation---changed scores are to be expected, because different databases and formulae were used in the different years.  In order to assess progress in ocean health, the 2012 scores were recalculated using the techniques updated in 2013, and most values across the 2 years are fairly close.
  • More recent data: When calculating the scores for a new year, more recent data are used if they become available. If the goal’s mathematical model did not change since the original 2012 assessment, the use of updated data layers can be responsible for the changed score. For example, Sierra Leone’s score for the Lasting Special Places sub-goal improved by more than 3,400% (from 0.23 to 8) because the 2013 data reflected the fact that the country designated four marine protected areas in 2012, increasing the amount of area protected from almost none to slightly more than 11,000 square kilometers.  South Georgia and the South Sandwich Islands’ score for the same sub-goal improved by 13% (from 71 to 80) after establishing a 1 million square kilometer marine protected area.  In these cases, the difference is due to an actual change in health (although we always recommend comparisons among recalculated scores to understand if there’s been a change in health). Note that the same does not apply when the new data are not more recent, but simply processed in a different way than in 2012 (see following section).
  • Small numbers: For a low score, a score increase of only a few points represents a large percentage increase.  If a country scored 16 in one year and 20 the next the 4 point change is equivalent to a 25% increase; however a 4 point increase for a country that initially scored 60 would only represent a 7% increase.  

How can a goal score be higher than both of its sub-goal scores?

This is the case for Food Provision, where the global score is 33, but the sub-goal scores are 31 for Wild-Caught Fisheries and 26 for Mariculture. The Food Provision score is not simply the arithmetic average of the two sub-goal scores. Instead, it is a yield-weighted average. That is, for each country the Fisheries score is weighted by the number of metric tons caught divided by the total number of metric tons of seafood produced both by fisheries and mariculture. Similarly, the Mariculture score is weighted by the number of metric tons of seafood raised divided by total seafood production by fishing and mariculture. High Mariculture scores tended to occur with low Fisheries scores, so yield weighting produced Food Production scores for those countries that are higher than the score for either sub-goal. Since the global Food Provision score is the area-weighted average of country scores, each of which was produced as a yield-weighted average of the two sub-goal scores, yield weighting also could boost the global score.

Why do so many regions score 100 on some goals?

Multiple scores of 100 can originate in two ways. 

A region will score 100 for any goal or sub-goal where the current Status equals its reference point (target), the Trend of Status scores over the most recent five years is positive, and Resilience measures equal or exceed the cumulative Pressures. For Carbon Storage, Coastal Protection, Livelihoods & Economies (including both the Livelihoods and Economies sub-goals) and Sense of Place (and its Lasting Special Places sub-goal) many region achieved those conditions and scored 100. There are no scores higher than 100, because all status scores are capped at 100. Thus, for example, even if a region expanded its coastal habitats beyond the 1980 reference values, its status score would be capped at 100.

For both Mariculture and Tourism & Recreation, there is no established reference point for how much mariculture or tourism a country should have, so the score of the best performing country was used as a benchmark to scale the performance of all countries from 0 to 100. In both cases the distribution of scores was quite skewed, so for Mariculture the score for the 90th percentile country was used as the reference point and all higher scoring countries were scored as 100; for Tourism & Recreation all countries scoring higher than the 95th percentile received 100.  

Looking forward, what are the biggest aims of the
Ocean Health Index?

In order for the Ocean Health Index to achieve its overarching goal of improving ocean health, the following steps will be needed:
  • Gain broad public acceptance of the new definition of ocean health that includes benefits to people. 
  • Gain broad acceptance of the value of regular, quantitative measurement of Ocean Health. 
  • Gain broad agreement on the need to collect and report---in an agreed-upon format-- all of the data needed by the Ocean Health Index (at whatever scale it is being used) as well as data needed by other assessments  related to ocean health.  
  • Engage individual nations to construct their own country- or territory-level Ocean Health Index that is tuned to their situations and incorporates any higher quality local information and knowledge that they possess. 
  • Continue measurement of the Ocean Health Index (and other assessment tools) for long periods to monitor progress toward ocean health and guide actions thereto.  
  • Restoring ocean health will take decades and, for some things, several generations.  We hope that the Ocean Health Index, along with patience, commitment and continuity of effort, will be an important guide in that quest.



Follow us